Rising CFRTP CFRP Prepreg Machinery Manufacturer

Why Jota Thermoset/Thermoplastic CFRP CFRTP Prepreg Manufacturing Machine

Since the 1st quarter of 2020, our Jota company has been gathering all the technical strength and related resources to develop and produce thermoplastic/thermoset CFRP CFRTP prepreg manufacturing equipment.

Our Continuous Fiberglass Reinforced Thermoplastic Prepregnation Uni-directional Tape (CFRTP- UD Tape) Production line:

Now, Jota’s thermoset prepreg machine is released.

Jota thermoset prepreg manufacturing involves 2 machines:

• Hot melt resin coater
• Hot melt prepreg manufacturing machine

The 1st machine is the resin coater, its function is to coat resin to paper or film, the resin pre-coated paper or film will then be used on the 2nd prepreg manufacturing device for prepregs production;

Such hot melt resin coater’s main parameters are shown below:

• Coating width: 300mm-1600mm
• Coating weight: 5gsm-1200gsm
• Max. speed: 40m/min
• Coating precision: ±0.5g/30g

The below video is the resin filmer’s demo video, please watch it for reference.

After introducing the 1st resin filmer, now comes the 2nd machine – the prepreg manufacturing machine.

Such prepreg machine utilizes heat and pressure through precision compaction rolls to compact pre-coated film or paper’s resin to fiber rovings, thus successfully manufacturing thermoset prepreg.

Glass rovings creel system is designed to unwind individual fiber tows.

Before entering compaction rolls, these fiber tows will be guided by a comb and spread by a spreader.

The main parameters of such a prepreg-making machine are listed below:

• Pre-impregnate width: 300-1600mm
• Pre-impregnated fiber weight: 20-1200g/m2
• Pre-impregnate speed: 1-20m/min

Because the video can show the prepreg machinery’s working effect more intuitively, I uploaded the demonstration video to Youtube for your reference.

In order to help you understand the CFRP CFRTP prepreg machine more deeply, our Jota marketing team has heartily written out the following FAQ guide for your reference.

After you read the following FAQ guide, you will be more familiar with the CFRP CFRTP prepreg manufacturing process.

If you are interested in purchasing a prepreg machine for CFRTP CFRP prepreg production, you are also welcome to send us an inquiry on this website and tell us your specific needs.

Hot Melt Thermoset/Thermoplastic CFRP CFRTP Prepreg Manufacturing Machine Ultimate FAQ Guide

CFRP CFRTP

CFRTP

CFRTP refers to continuous fiber-reinforced thermoplastic composites, it has more than 25 years of history.

Many kinds of reinforcing fibers are used in CFRTP production, such as:

• Carbon fiber
• Glass fiber
• Kevlar fiber

Matrix mainly includes:

• PP
• PA
• PC
• PEI
• PPS
• PEEK
• Another thermoplastic matrix

In CFRTP’s early development, it was mainly used in aviation and military fields.

Beginning in 2002, the CFRTP demand began to grow substantially and was gradually applied to automobiles, sports equipment, transportation, industry, and other fields.

In 2014, the continuous fiber-reinforced thermoplastic composite materials’ global output value reached $US188.7 million, with an average of 12% annual growth rate.

There are many well-known thermoplastic carbon fiber composite suppliers in the world, mainly including:

• DSM (The Netherlands)
• Evonik (Germany)
• Arkema (France)
• SOLVAY (Belgium)
• Teijin (Japan)
• Toray (Japan)
• Hexcel (USA)
• DuPont (USA)

CFRP

CFRP refers to carbon fiber-reinforced plastics.

Carbon fiber-reinforced plastics are a new type of composite material.

This material uses carbon fiber as the reinforcement and polymer resin as the matrix.

Among many lightweight materials, carbon fiber-reinforced composite materials are highly strong and rigid, lightweight, and are widely used in aerospace and military products.

Such material is also used in car structural parts, its weight-reducing effect is particularly obvious, and it is 50% lighter than steel and 30% lighter than aluminum.

Major automobile companies are paying attention to this material.

The carbon fiber reinforced composite materials’ excellent mechanical properties, thermophysical properties, and thermal ablation properties make it widely used in:

• Nuclear reactors
• Solid rocket nozzles
• Heat exchangers and retrorocket’s nozzle throat
• Long-range missile nose

Secondly, carbon fiber-reinforced composite materials can be used as raw materials in the electronic industry, it is usually used in PCB production;

And it is also used as raw materials for artificial heart valve occluders in the medical industry.

CFRP properties

The CFRP properties are mainly reflected in 3 aspects:

• Mechanical properties
• Thermophysical properties
• Thermal ablation properties

CFRP density is just about 1.7g/cm3, it is the lightest among structural materials that withstand high temperatures.

When the temperature reaches 2200℃, it can still maintain the same strength as room temperature;

It has high fracture toughness, fatigue resistance, and creep resistance;

Moreover, the tensile strength and elastic modulus of CFRP are higher than that of ordinary carbon materials, and the fiber orientation will obviously affect the material strength.

When subjected to force, its stress-strain curve shows a “pseudoplastic effect”.

That is, at the initial stage of load application, the relationship is linear, and then it becomes a bilinear relationship.

After unloading and then loading again, the curve is still linear and can reach the original load level;

• The thermal expansion coefficient is small, the heat capacity is high, a large amount of heat energy can be stored, the thermal conductivity is low, and the performance of thermal shock and thermal friction resistance is excellent;

• Good thermal ablation resistance performance.

Thermal ablation performance refers to the phenomenon of solid materials’ surface loss under the heat flow.

Through the ablation of the surface material, a large amount of heat is taken away and the heat can be prevented from flowing into the material.

CFRP density

The CFRP density is about 1.76g/cm3-1.80g/cm3, while the density of steel is about 7.87g/cm3, titanium is 4.5g/cm3, aluminum is 2.7g/cm3, CFRP is much lighter than steel, titanium, and aluminum.

Replacing steel with carbon fiber will reduce weight by 4 times, replacing titanium will reduce weight by 2 times, and replacing aluminum will reduce weight by 1 time.

Why is CFRP so strong?

• CFRP physical properties

CFRP is mainly composed of two parts: carbon fiber and resin matrix.

Carbon fiber is mainly made of high-molecular materials, such as viscose fiber, polyacrylonitrile fiber, and pitch fiber.

The resin matrix mainly uses epoxy resin and polyimide resin.

Epoxy Resin

CFRP has excellent properties.

• The specific strength of epoxy resin-based carbon fiber (EP/CF) composite materials is 4.8-7.2 times that of steel
• The specific modulus is 3.1-4.2 times that of steel
• And the anti-fatigue strength is about 2.5 times that of steel, 3.3 times that of aluminum

Moreover, the high-temperature performance of CFRP is good.

When the working temperature reaches 400℃, its strength and modulus remain basically unchanged.

In addition, CFRP also has the following outstanding properties.

• Low density and linear expansion coefficient
• Corrosion resistance
• Creep resistance
• Good integrity
• Delamination resistance
• Impact resistance

Among the existing structural materials, the comprehensive index of CFRP’s specific strength and specific modulus is the highest.

In the process of processing and molding, EP/CF composite materials are easy to be integrally formed in a large area, and the forming is stable.

The basic mechanical properties of different fiber CFRP are shown in the table below.

GFRP VS CFRP

There are three main types of fiber composite materials (FRP):

• Carbon Fiber Reinforced Polymer (CFRP)
• Glass Fiber Reinforced Polymer (GFRP)
• Aramid Fiber Reinforced Polymer (AFRP)

In FRP materials used in construction projects, the fiber volume content is generally 60% to 65%.

Carbon fiber is a fibrous carbon material with high strength and high elastic modulus.

According to different raw materials and production methods, it is mainly divided into:

• Polyacrylonitrile-based carbon fiber
• Asphalt base carbon fiber

The former is a fiber obtained by heating polyacrylonitrile fiber at high temperature in an inert gas, it is high-strength carbon fiber;

The latter is a fiber made from coal tar or petroleum pitch and sintered at a high temperature, it is carbon fiber with a high elastic modulus.

Carbon fiber polymer (CFRP) is a unidirectionally arranged carbon fiber composite sheet, it is formed by carbon fiber as a component, and resin as a matrix by molding.

It has extremely superior qualities such as:

• High strength
• Lightweight
• Corrosion resistance
• Aging resistance
• Stable physical properties

The tensile strength of high-strength carbon fiber polymer can reach 3400MPa, which is 7-10 times higher than that of steel.

The elastic modulus is from 2.3 x 105MPa to 3.9 x 105MPa, while the commonly used carbon fiber polymer sheet is only a few hundred grams per square meter.

At the same time, according to natural and accelerated exposure tests, the tensile strength of carbon fiber polymer and the bonding strength with concrete will not change within 50 years, and it has sufficient weather resistance.

Moreover, the fatigue performance of carbon fiber polymer is better than that of steel and concrete materials.

Glass fiber polymer (GFRP) has a strength of 590Mpa-1130MPa and a density of 1.5g/cm3-2.0g/cm3.

It has good corrosion resistance.

Using it can comprehensively improve the reinforced component’s various mechanical properties, and using it can also improve the force performance of the reinforced components.

At the same time, the linear expansion coefficient of glass fiber polymer is close to that of concrete, it has good working performance with concrete structures, and the construction is simple and quick.

It is a highly advantageous reinforcement material.

Glass fiber mainly includes:

• E glass fiber (electrical insulation)
• C glass fiber (chemical resistance)
• S glass fiber (high strength)
• M glass fiber (high elastic modulus)
• AR glass fiber (alkali-resistant glass)

S Glass Fiber

Among them, E glass fiber and its related products are used most in the reinforcement of concrete structures.

The supporting resins mainly include:

• Unsaturated polyester resin (UP)
• Epoxy resin
• Phenolic resin
• Furan resin
• Melamine-formaldehyde resin
• Polybutadiene resin
• Silicone resin
• Polyurethane resin
• Polyethylene
• Polypropylene
• Styrene
• ABS resin
• Polyamide
• Polycarbonate
• Polyoxymethylene
• Polyimide
• Polysulfone
• Polysulfone ether
• Polyaryletherketone
• Polyphenylene sulfide

Epoxy resin is most commonly used in the reinforcement of concrete structures.

Aramid is the abbreviation for aromatic polyamide fiber.

Aramid fiber-reinforced composite material (AFRP) is a high-performance structural material developed in the 1970s.

In addition to high strength and high elastic modulus properties, aramid fiber also has high heat resistance.

Because aramid fiber is a rigid macromolecular chain, it has poor mobility and can maintain high strength even at high temperatures.

The commonly used aramid fiber is aramid 1414, the tensile strength of the original filament is 2.67-2.9GPa, and the elastic modulus is 38.9-50GPa.

For example, to produce aramid fiber with a high elastic modulus, it must be thermally stretched.

At this time, the strength of the fiber will decrease slightly, but the elastic modulus can increase to 88.9GPa, or even as high as 133GPa.

Why is CFRP stronger than GFRP?

Why GFRP (glass fiber composite material) is not as good as CFRP (carbon fiber composite material) in engineering reinforcement?

Because glass fiber composite materials are inferior to carbon fiber composite materials in terms of:

• Elastic modulus
• Ultimate strength
• Durability

Generally speaking, the elastic modulus of GFRP is 40GPa, and the tensile strength is 900 to 1100MPa (D25);

While the tensile strength of CFRP is generally more than 3500Mpa, which is 7 to 9 times that of steel, the elastic modulus is 230 to 430Gpa, and the specific strength is above 2000Mpa.

How strong is FRP?

The application of FRP is actually quite extensive, such as using FRP bars instead of steel bars to pour concrete.

Some foreign bridges or reinforcement structures have begun to use FRP, and foreign countries will continue to update the basic specifications every 5 years.

Because the FRP composite material manufacturing technology is getting higher and higher, the strength is also increasing, and the cost is also decreasing.

Why FRP is popular?

• 1. CFRP tensile strength 1200Mpa+ > steel bar (400Mpa+), GFRP 600Mpa+ > steel bar (400Mpa+), the elastic modulus is smaller than steel bar;

• 2. Corrosion resistance, FRP material does not need to consider corrosion problems;

• 3. The thermal expansion coefficient of FRP composite material is similar to that of concrete;

When the surrounding temperature changes, FRP and concrete work in coordination, and there will be no large temperature stress between the two;

• 4. High strength-to-weight ratio FRP material can reduce the weight of the structure, and it is convenient for construction;

Its weight is generally 20% of steel;

• 5. The FRP structure is stable with fewer cracks.

FRP adds pre-stress to prevent the structure from cracking or cracking late under normal use.

This can increase the structure stiffness itself, reduce vibration and elastic deformation, improve the elastic strength of the tension module, and make the original resistance stronger.

Currently, the widely used FRP steel bars are CFRP (carbon fiber) and GFRP (glass fiber) types.

GFRP, due to its price advantage (compared to CFRP), is currently used more.

FRP-type bars basically have two major components.

With the improvement of manufacturing technology, the cost is decreasing year by year and the strength is increasing.

The picture below shows the production process:

In the calculation process of reinforcement design, the big difference is that double-layer FRP reinforcement cannot be simply equivalent to a single-layer calculation.

Because the stress-strain curve of FRP material is linear, and FRP has a lower elastic modulus, the curvature is larger when it breaks.

Therefore, compared with ordinary steel bars, FRP bars should consider the factor of deformation when designing.

Can FRP be used outdoors?

In recent years, FRP materials have been increasingly used in various outdoor civil engineering.

Due to outdoor environmental factors and various external forces, civil structures such as reinforced concrete are easy to be damaged greatly outdoors.

And steel bars are prone to corrosion, which greatly reduces the carrying capacity of the structure, and the maintenance costs are also increasing day by day.

Steel Bars

FRP material has good corrosion resistance, high specific strength, and good fatigue resistance.

And FRP materials are designable.

Designers can:

• Select appropriate fibers and resins
• Adjust the proportion of each component material
• Determine the laying angle of the fibers
• Select the appropriate processing method to meet the user’s requirements for material stiffness, strength, etc.

Therefore, the FRP concrete structure emerges as the times require.

FRP materials can adapt to the needs of large-span, high-rise, heavy-load, high-strength, and lightweight development of modern engineering structures, and withstand harsh conditions.

It meets the industrial requirements of modern construction technology.

Therefore, it is being used by more and more:

• Bridges
• Various civil buildings
• Marine and offshore
• Underground engineering
• Other structures

The development of the civil engineering discipline, to a certain extent, depends on the development and application of new materials with excellent performance.

FRP materials have excellent properties and have become a hot spot in the field of civil engineering research and application.

What type of material is GRP?

In nature, we always think that humans are the smartest.

But in some respects, some animals understand better than we do.

For example, some birds use straws, branches, and clay to build nests.

People are inspired by the bird’s nest.

When building a house, they will tamp clay into a wall, and the clay will be added with straw and lime.

This is the most primitive reinforced composite material.

Composite materials are made of several materials with different properties, through physical or chemical methods, to form a new material with better performance.

In ancient times, people realized that a single material could not meet the needs of users.

According to different needs, the characteristics of various materials are combined to become new material.

Therefore, composite materials are both a new type of material and ancient material.

FRP, when you see this word for the first time, are you also confused, is it a new type of glass or special steel?

FRP is what we call fiber-reinforced plastics, and it is a composite material.

This material is made of various resins as a matrix, drawing glass into very thin fiber filaments, and then impregnating glass fiber filaments with resin.

This kind of material is widely used in construction, automobile, communication, and other fields.

Glass is a low-strength and brittle material, but after the glass is melted and drawn into very thin glass fiber filaments, its performance will change.

This kind of glass fiber yarn is very thin and strong, and can even be woven into cloth.

• Glass fiber reinforced plastic is like reinforced concrete;

• Glass fiber filaments are like hard steel bars in concrete;

• And resin is like a binder—the combination of cement, glass fiber filaments, and resin, which has the composition of glass and the same strength as steel, that is why this material is called FRP.

FRP is often used in life, such as outdoor trash cans, urban sculptures, outdoor play equipment, etc.

So, how is this material made?

The density of FRP is low, only about 1/4 of that of steel, but the strength is very high and it has good corrosion resistance.

This is a performance that other metals do not have, so in many fields, FRP has replaced metal materials.

But at the same time, FRP also has shortcomings such as easy deformation and easy aging.

What is the difference between FRP and GRP?

Glass fiber reinforced plastic FRP is also called GRP, in fact, the two are the same material, namely fiber-reinforced plastic.

Generally speaking, it refers to a reinforced plastic that uses unsaturated polyester, epoxy resin, and phenolic resin as the matrix, and glass fiber as the reinforcing material.

It is called glass fiber reinforced plastic, or glass fiber reinforced plastic.

Pay attention to distinguishing FRP from tempered glass.

Due to the different types of resins used, there are:

• Polyester fiberglass
• Epoxy fiberglass
• Phenolic fiberglass

FRP has many special features, such as:

• Light
• Hard
• Non-conductive
• Stable in performance
• High in mechanical strength
• Corrosion-resistant

It can replace steel in the manufacture of machine parts and the shells of automobiles and ships.

Features of FRP

• 1. Corrosion resistance

The difference in resin performance gives FRP different corrosion resistance so that FRP can be used for a long time under the corrosive environment of different gas and liquid media.

• 2. Flame retardant

High-quality resins and flame-retardant additives give FRP excellent flame-retardant properties.

Generally, the oxygen index of flame-retardant products is greater than 26, the flame diffusion coefficient is less than 25, and the smoke density is less than 500.

• 3. Lightweight and high strength

The perfect combination of alkali-free glass fiber yarn and resin gives the product unique lightweight and high-strength characteristics.

The specific gravity of the product is 1/4 of steel, which is suitable for various load-bearing structures under corrosive environments.

• 4. Anti-aging

The product is made of high-quality matrix resin and anti-aging additives, so the product has long-lasting anti-aging performance, can maintain long-term gloss and continuous high strength, and a service life is more than 20 years.

• 5. Designability

In addition to the flexible design performance of FRP, the color of the product can be customized according to customer requirements, the shape and size can also be cut and spliced into the size required by the customer.

• 6. Safe and anti-slip

The high elastic modulus and different surface effects make the FRP grille have anti-slip performance.

The slight elasticity can reduce the fatigue of the staff.

The crescent surface, sand surface, diamond surface, and different surfaces can meet the anti-slip performance of different applications.

• 7. Electrical performance

Glass fiber and high-performance resin enable the glass fiber reinforced plastic to have superior electrical properties, the breakdown strength can reach 10Kv/mm, and there is no electric spark when metal tools resist;

The product is non-magnetic and can be used safely in anti-electromagnetic and anti-explosion environments.

• 8. The cost is low, and the product shape is easy to realize.

CFRP use

CFRP is the abbreviation of Carbon Fiber Reinforced Polymer/Plastic.

It is characterized by lightweight and high strength.

Many parts of F1 racing cars are made of this material, such as monocoque, Boeing 787 passenger aircraft, and Apache helicopter.

CFRP is widely used in engineerings, such as bridge reinforcement, repair, and maintenance of various civil construction projects.

The structure of some projects has been damaged due to the accumulation of time, which can be repaired by carbon fiber structure reinforcement and maintenance.

CFRP is also widely used in:

• Military
• Aviation
• Sporting goods
• Racing
• Other fields

This material not only has the advantages of other composite materials but also has many unique characteristics.

It is a material with excellent mechanical and physical properties.

• 1. The entire system is composed of carbon elements.

Because carbon atoms have a strong affinity for each other, C/C composite materials have good stability regardless of low temperature or high temperature.

• 2. The carbon material has a high melting point and excellent heat resistance.

It can withstand a high temperature of about 2000°C.

It is currently the material with the best high-temperature mechanical properties in an inert atmosphere.

More importantly, as the temperature rises, the strength of this material does not decrease, even higher than that of the greenhouse, which is unmatched by other structural materials.

• 3. The density is small (less than 2.0g/cm³), only 4/1 of the nickel-based superalloy and 1/2 of the ceramic material.

• 4. Good anti-scorching performance, can withstand temperatures higher than 2000C°, suitable for short-time burning environments, such as the nozzles and throat linings of rocket engines in the aerospace industry.

• 5. Excellent friction and wear resistance, low friction coefficient, and stable performance.

It is the best material for manufacturing various friction parts.

Excellent corrosion resistance, insoluble in organic solvents, acids, and alkalis.

In 1981, someone soaked carbon fiber in a strong alkaline sodium hydroxide solution.

After more than 20 years, he still maintained the original fiber shape.

X-ray transmission is good, carbon fiber composite material has very good penetration, and the image is very clear.

• 6. Excellent seismic resistance, it is a very good material used in precision machinery and construction.

• 7. Easy to shape.

Because carbon fiber is a flexible material, it can be woven into various specifications of carbon fiber cloth.

After carbon fiber cloth is arbitrarily cut, through co-curing, co-bonding, resin transfer molding (RTM), fabric pre-forming, stitching, z-pin, and other methods, a more complex overall piece is manufactured.

• 8. Good anti-fatigue and anti-creep properties.

In the torsion and bending tests, carbon fiber structural part with a three-dimensional overall woven structure, the fatigue limit can reach 90%.

Why is CFRP expensive?

Weight loss is not only reflected in the sports field;

In the automotive field, in order to pursue faster speeds, more stable cornering, and more precise control, weight-reducing design and technology have always been the ultimate pursuit of engineers.

Compared with traditional materials, carbon fiber materials have many advantages.

But why is carbon fiber material still not popular?

The reason is that the cost of carbon fiber materials is too high and the price is too expensive.

This is the reason why carbon fiber materials cannot be popularized in many fields.

• 1. Not all carbon fiber materials are expensive, but high-strength carbon fiber materials are expensive;

Carbon fibers have different strengths and specific modulus, so different carbon fibers have different prices.

Take Japan’s Toray carbon fiber price as an example.

The price of T300 is more than 100RMB (USD$15.15) per kilogram, while the price of T1000 has reached more than 1,000RMB (USD$151.51) per kilogram.

The higher the price of carbon fiber materials, the higher the strength;

And the higher the strength, the rigidity and safety of the vehicle will be more guaranteed.

• 2. High-strength carbon fiber materials have been monopolized by several companies;

Carbon fiber is not made by everyone.

Toray, Toho, and Mitsubishi are the three giant companies producing carbon fiber materials in Japan.

Among them, Toray is the benchmark.

Although the naming of other manufacturers’ carbon fiber materials is different from Toray, when marking the strength, they will be marked against Toray’s same specification materials.

In this way, carbon fiber is in a semi-monopoly state, and the pricing power is in the hands of the supplier, and the price will naturally rise.

• 3. Carbon fiber materials have very strict requirements on the processing environment and technology, which further increases production costs.

In the process of bonding carbon fiber cloth, if dust sticks to it, the strength will decrease.

Therefore, the molding room of the carbon fiber material structure is dust-free, with constant temperature, constant humidity, and a constant difference between indoor and outdoor atmospheric pressure.

Compared with most ordinary workshops, the cost of such a workshop is much higher.

CFRP cost

Regarding the price of carbon fiber composite materials, because there are different types and uses, the prices of different types of carbon fiber composite materials are different.

Carbon fiber composite materials mainly include the following categories:

• Carbon fiber reinforced resin matrix composite materials
• C/C composite materials
• Carbon fiber reinforced metal matrix composite materials (CFRM)
• Carbon fiber reinforced ceramic composite materials
• Carbon fiber reinforced rubber composite materials

As an advanced composite material, carbon fiber composite material (CFRP) has a series of advantages such as:

• Lightweight
• High modulus
• High specific strength
• Low thermal expansion coefficient
• High-temperature resistance
• Thermal shock resistance
• Corrosion resistance
• Good vibration absorption

It has been widely used in aerospace, automotive, and other fields.

Prepreg

Prepreg definition

Prepreg is a composition formed by using resin as the matrix, impregnating continuous fibers or fabrics under strictly controlled conditions, and mixing the resin matrix and reinforcement.

It is an intermediate material for manufacturing composite materials.

Classified by physical state, prepregs are divided into:

• Unidirectional prepregs
• Unidirectional fabric prepregs
• Fabric prepregs

According to the different resin matrix, the prepreg is divided into:

• Thermoset resin prepreg
• Thermoplastic resin prepreg

Different reinforcement materials, it is divided into:

• Carbon fiber (fabric) prepreg
• Glass fiber (fabric) prepreg
• Aramid (fabric) prepreg

According to different fiber lengths, it is divided into:

• Short fiber (below 4176mm) prepreg
• Long fiber (1217mm) prepreg
• Continuous fiber prepreg

According to the different curing temperatures, it is divided into:

• Medium temperature curing (120℃) prepreg
• High-temperature curing (180℃) prepreg
• ＞200℃ curing temperature prepreg

Prepreg manufacturing process pdf

Regarding prepreg manufacturing, the current trend is that hot melt thermoplastic prepreg manufacturing becomes more and more popular.

The following photo indicates the typical process of hot melt thermoplastic prepreg manufacturing:

Fiber yarn unwinds from the creel, passes through a spreader, combines with top paper (coated with thermoplastic resin) and bottom paper, then passes through 2 sets of compaction rollers together for merging, and finally wound to prepreg jumbo roll.

Our Jota hot melt thermoplastic prepreg manufacturing machine doesn’t need the top and bottom paper, please leave your Email through this website’s inquiry form.

Once our machine is released, we will send a PDF file of the upgraded prepreg manufacturing process to you in a timely.

Advantages of prepreg

The use of new carbon fiber composite material prepreg as a manufacturing tool has the following advantages:

• 1. High precision

Since the tooling and the parts are both composite materials, their thermal expansion coefficients are similar.

In the heated state, the two heat up or cool at the same rate, so the part deforms less in the solidification and subsequent processing steps.

The accuracy of the finished product is greatly improved, and the repair and troubleshooting work is reduced after heat treatment.

• 2. Maximum strength characteristics.

A typical manual layup will have a large excess of resin, which will increase the brittleness and reduce overall performance.

Most prepregs contain about 3% resin, which is ideal for achieving maximum curing performance, which cannot be achieved with conventional manual lamination.

• 3. Uniformity and repeatability.

The thickness of the prepreg is uniform, and each part coming out of the mold may theoretically be the same.

Vacuum bagging technology still has certain errors in processing molds, but prepregs can greatly reduce these problems.

Vacuum Bagging

• 4. Reduce curing time.

After the heat curing cycle, there is no need to wait the standard 48 hours to fully cure.

• 5. Good appearance.

Although prepreg processing still requires mold preparation and demolding, prepreg processing can eliminate air bubbles and make it easier to obtain a smooth and shiny surface.

What is prepreg used for?

Prepreg is an intermediate material in the manufacture of composite materials and their parts, it constitutes the basic unit of composite materials.

The uniformity and stability of prepreg quality are important factors to ensure the quality and reliability of composite materials and their parts.

The high specific strength, specific stiffness, and superior design performance of resin-based composite materials can effectively improve the spacecraft’s structural quality.

Spacecraft

It is the development focus of today’s aerospace materials and is gradually replacing traditional metal materials.

However, due to poor dielectric properties, heat resistance, dimensional stability, and moisture resistance of epoxy resins, the usage rate of epoxy resin-based prepregs is gradually decreasing.

While new materials such as polyimide, bismaleimide, and polyether have greatly improved heat resistance and dielectric properties, they also have processing defects such as poor solubility and high molding temperature.

It needs further improvement.

In recent years, the application prospect of cyanate ester resin has become more and more extensive, because its performance combines the high-temperature resistance of BMI and the good processability of EP.

Following PI and BMI, cyanate ester resin has become another matrix resin for high-performance aerospace composite materials.

In recent years, the amount of carbon fiber composite materials used in space vehicles such as satellites and spacecraft has increased year by year.

Especially carbon fiber prepreg composite materials, which have been widely used in the main structures of satellites’ central bearing cylinders, substrates, and connecting frames, satisfying aerospace’s multiple functional requirements.

Prepreg material

The materials used to manufacture prepreg mainly include the following:

1. Reinforced materials

The main requirements of prepreg reinforcement materials:

• ①Good wettability to resin;
• ②Meet the molding requirements of products with complex shapes;
• ③Meet the main performance requirements of the product.

Reinforcing fibers include glass fiber, carbon fiber, and aramid fiber, etc.

The commonly used forms of reinforcement include unidirectional fiber, checkered cloth, twill cloth, and multi-axial cloth.

2. Matrix material

The main function of the matrix resin:

• ①Bonding fiber’s orientation and position into a whole;
• ②Transmit stress during the product stress process.

Generally speaking, it is difficult to meet the requirements of process performance through a single resin.

And it is usually achieved by using several resin combinations, such as using several different epoxy resin combinations

Different epoxy resin combinations increase the viscosity of the resin system at room temperature or low temperature.

Phenolic epoxy resin can improve the reactivity and heat resistance of the resin system, and bisphenol A epoxy resin can adjust the viscosity of the resin system.

Studies have shown that the best resin system for prepregs is liquid bisphenol A epoxy resin, solid bisphenol A epoxy resin, and novolac epoxy resin.

The choice of matrix material should take into account the performance requirements of the composite material itself and the process operation requirements.

For example, the basic requirement of medium-temperature hot-melt epoxy resin prepreg is not sticky in summer and not brittle in winter.

This requires adjusting the proportions of different components so that the softening point of the resin system is 36-37°C in summer and 30-32°C in winter while limiting the curing temperature of the epoxy resin.

The best temperature is generally 120-130°C, and the curing time does not exceed 90 minutes.

• 3. Curing system

The curing system includes curing agents, accelerators, catalysts, and diluents.

According to the requirements of the prepreg, the prepreg needs to have a certain storage period at room temperature, so the curing system usually uses a latent curing agent.

The latent curing agent does not react with the resin under normal temperature and pressure, but under special temperature and pressure, it will promote the crosslinking and curing reaction of the resin.

This is conducive to the storage of the prepreg at room temperature.

This type of curing agent is usually a dispersion type curing agent, that is, it is solid at room temperature and cannot be dissolved in epoxy resin.

But when it is heated to near its melting point, it can be miscible with epoxy resin, and the curing reaction begins to occur quickly.

The main function of the accelerator is to promote the dissolution of the curing agent in the resin matrix and increase the curing reaction rate;

The toughening agent is to reduce the brittleness of the thermoset resin matrix and improve its impact resistance;

The diluent mainly reduces the resin viscosity and improves the process performance;

The catalyst mainly promotes the reaction of the resin in the curing and molding stage.

But it is also in a “latent” state under normal temperature and pressure, which is very beneficial to the actual production operation of the prepreg.

Resin content in prepreg

For epoxy prepregs, the resin content is usually 37% to 42% of the prepreg weight.

Specifically, the resin content of the thermosetting unidirectional prepreg is 31%, and the resin content of the thermosetting woven fabric prepreg is 35%.

Different types of prepregs

According to different fiber types, fiber arrangement, and matrix materials, a diverse group of prepreg products has been formed.

Among them, thermoplastic prepreg and thermoset prepreg are the most commonly used methods.

The performance comparison between the two is shown in the table below.

In terms of mechanical properties, unidirectional prepregs have no wefts and rely on resin matrix to bond fibers into sheet-like materials.

The load-bearing fiber can design the structure layer according to the force analysis, so the utilization rate of the mechanical properties of the yarn is the highest.

Fabric prepregs will inevitably cause fiber damage due to the buckling of the warp and weft of the fabric during the weaving process, thereby reducing the mechanical properties.

However, from the angle of easy manual layup operation and composite material structure with corners, fabric prepreg has its unique advantages.

Prepreg carbon fiber

Carbon fiber prepreg is made by laminating epoxy resin on carbon fiber through high-pressure and high-temperature technology.

The composite material made of carbon fiber yarn, epoxy resin, release paper, and other materials through the coating, hot pressing, cooling, laminating, winding and other processes are called carbon fiber prepreg, also known as carbon fiber prepreg.

Carbon Fiber Yarn

It is called prepreg because it is only the initial impregnation of resin and carbon fiber, and it is the final impregnation when the product is formed.

According to carbon fiber raw yarn:

• 1. PAN-based carbon fiber yarn (more than 90% of the market is this kind of carbon fiber roving);
• 2. Viscose-based carbon fiber yarn;
• 3. Pitch-based carbon fiber yarn.

According to carbon fiber specifications:

• 1K carbon fiber yarn;
• 3K carbon fiber yarn;
• 6K carbon fiber yarn;
• 12K carbon fiber yarn;
• Large tow carbon fiber yarn of 24K and above.

According to carbon fiber carbonization points:

• 1. Graphitized carbon fiber cloth can withstand the high temperature of 2000-3000 degrees;
• 2. Carbon fiber cloth can withstand the high temperature of about 1000 degrees;
• 3. The pre-oxidized carbon fiber yarn can withstand a high temperature of 200-300 degrees.

According to the weaving method:

• 1. Dry prepreg;
• 2. Wet prepreg;
• 3. Unidirectional prepreg;
• 4. Prepreg tape.

Prepreg carbon fiber process

Prepreg is the combination of resin and fiber before it is cured, and maintains a certain storage period.

During the storage period, it can be designed and formed at any time.

It is an intermediate material for making composite materials.

Carbon fiber prepreg is made by spreading carbon fiber tows (or carbon fiber woven cloth), combining with resin pre-coated on release paper under pressure and temperature, and then cooling, laminating, winding, etc.

It is intermediate composite materials processed by technology.

The common components of prepreg are:

• The bottom is a layer of release paper (white)
• The middle is the finished prepreg (black)
• The surface is covered with a layer of polyethylene film (blue)

Among them, the finished prepreg in the middle is composed of resin and fiber.

The resin of the prepreg is an uncured resin, mostly thermosetting resin.

There are many kinds of thermosetting resins, the commonly used ones are:

• Phenolic resin
• Epoxy resin
• Dima resin
• Vinyl resin
• Cyanate resin
• Other thermose resin

Among the carbon fiber prepregs, epoxy resin is the most widely used.

In some high-temperature resistant occasions, Dima and oxyacid resins are used.

Prepreg has the following characteristics:

• 1. The weight and resin content can be precisely controlled;
• 2. Strong design ability, top-level design of strength and rigidity can be carried out according to the characteristics of product use;
• 3. Direct use, free of glue and brushing, less labor-intensive, and more environmentally friendly.

Prepreg is widely used.

At first, it was used in the autoclave process, and later it can be used in non-autoclave processes such as molding and vacuum pressing.

There are many processes.

• 1. Autoclave process

The autoclave process is one of the most common forming methods for fiber composite materials, especially in the field of aerospace, which is as high as 80%.

The formed components are mostly used in primary and secondary bearing structures such as the aerospace field, as well as many fields such as national defense, rail transit, electronic communications, automobile manufacturing, and sports crystal materials.

The picture below is the autoclave:

The schematic diagram of the autoclave process is as follows:

Lay the carbon fiber prepreg on the mold according to the layup requirements, seal the blank in a vacuum bag, and place it in a carbon fiber autoclave.

In the vacuum state, through the procedures of:

• Heating
• Pressurizing
• Heat preservation
• Cooling
• Decompression of the autoclave equipment

The uniform temperature and uniform pressure provided in the autoclave are used to achieve solidification, thereby forming a high-quality surface and interior carbon fiber composite parts with complex shapes.

An important reason for using autoclaves is to provide sufficient pressure to the prepreg to inhibit the formation of pores.

The products produced in this way have good performance and can be used as structural parts.

Therefore, the autoclave process is widely used in aerospace, but the autoclave process also has the disadvantages of high cost and low efficiency.

• 2. Vacuum bag pressing process

Due to the high cost of autoclaves, researchers have developed a vacuum bag pressing process.

The pre-processing of the vacuum bag pressing process is similar to the autoclave process, and the post-curing does not use an autoclave but a curing furnace.

The curing oven is cheap, but there is no pressure.

In the case of vacuuming, the pressure difference is only a barometric pressure.

Therefore, to obtain similar porosity, higher requirements are placed on resin and prepreg.

Studies have shown that semi-wet prepregs can effectively improve gas permeability.

The dry fiber is used as a channel for exhaust gas.

When the part is solidified, the entrained gas and volatile matter can be exhausted through the channel.

• 3. Prepreg molding process

A method in which a certain amount of prepreg is added to a metal pair mold and then heated and pressurized to solidify and shape.

The relative production efficiency of prepreg molding is high, and it is convenient to realize specialized and automated production.

Especially when using fast-curing prepreg, the time can be shortened to less than 10 minutes for one mold;

The product has high dimensional accuracy, good repeatability, and a smooth surface;

It can form products with complex structures at one time;

Suitable for mass production.

The disadvantage is that mold manufacturing is complicated, the investment is large, and the press is limited, it is most suitable for mass production of small and medium composite products, and it is not easy to produce large-size products.

There are many applications of prepreg molding, such as aerospace, automobiles, electronics, medical equipment, sports equipment, etc.

• 4. Prepreg blow molding

This process is developed on the basis of prepreg molding and is mainly used to produce hollow carbon fiber products.

The craft was developed in Taiwan, China.

Initially, the racket is filled with a foaming agent in advance, placed in a mold, pressurized, and foamed after heating, and a certain pressure is generated to spread the prepreg and shape it.

But the racket made in this way will have a squeaking sound, and the weight cannot be properly controlled.

Later they creatively developed the “blow-molding” method.

It is said that the first blow-molded airbag blown inside was developed by people from a food company that used hot dog casings as the blowing tube.

Therefore, innovation is not always so big, but practical.

The Chinese will have a lot of native methods in this regard, and it would be nice if they can improve better.

It is said that this material has been used for quite a while, and then nylon airbags were invented, and they were not used.

This process is currently the mainstream technology for sporting goods, including carbon fiber badminton rackets, golf clubs, baseball rackets, bicycles, and other products, all produced by this process.

• 5. Coiling process

The carbon fiber coiled tube forming process is a composite material product molding method that uses carbon fiber prepreg to be hot-rolled on a tube coiling machine.

This process is currently the most important production process for carbon fiber fishing rods.

Carbon Fiber Fishing Rod

The tube rolling process is also known as the tube rubbing process.

I have really seen the most rustic carbon fiber fishing rod factory, and it is really the old lady rubbing the tube with prepreg.

The tube coiling process, specifically, uses a hot roller on a tube coiler to soften the prepreg and melt the resin adhesive on the prepreg.

Under a certain tension, during the rotating operation of the roller, the friction between the roller and the mandrel is used to continuously roll the prepreg onto the tube core.

After rolling to the required thickness, then cool and set the shape by the cold calendering roller.

The coiled product is taken out from the machine, then wrapped with heat-shrinkable film, and cured in the oven.

After the pipe is cured, the heat-shrinkable film and the inner core mold are removed, and the composite coiled pipe can be obtained.

In addition to producing round tubes like fishing rods, this process can also produce square tubes, triangles, and other special-shaped tubes for use in different fields.

• 6. Winding process

Broadly speaking, the previous pipe rolling process can also be said to be a winding process, but this process does not use continuous prepregs but has a certain laminated design.

In our daily winding process, continuous prepreg can be used to produce pipes, gas cylinders, etc. through a certain angle design.

Therefore, the prepreg here is different from the traditional prepreg, and narrow prepreg tape is used.

Carbon fiber prepreg has obvious advantages and is widely used in fishing tackle, sports equipment, sporting goods, aerospace, and other fields.

It is used in the military to manufacture rockets, missiles, satellites, radars, bulletproof vehicles, body armor, and other important military products.

How do you use prepreg carbon fiber?

When making carbon fiber products, it is necessary to use prepreg as an intermediate material.

Whether carbon fiber products have excellent mechanical properties depends on whether the prepreg can play the role of connecting the past and the next.

Carbon fiber UD prepreg products include paper tube, release paper or PE film, resin, and fiber composite, as shown below:

Advantage

As we all know, carbon fiber has high strength and low density.

Its strength can reach 6 to 12 times that of steel, but its density is less than 1/4 of steel.

Carbon fiber has the softness and plasticity of textile fiber and can be made into kinds of products according to the shape of the mold.

And it is not a metal material, has corrosion resistance, and long service life.

Prepreg advantages

• ①Good mechanical properties;
• ②Few product defects;
• ③Precise control of fiber volume content;
• ④Good consistency of performance and processing characteristics;
• ⑤The best performance/weight ratio.

Classification

• 1. Unidirectional prepreg (UD)

• 2. Fabric prepreg

① Plain weave: poor lay-up performance, high fiber bending rate.

② Satin: good covering performance, low fiber bending rate.

③Twill: Medium laying performance, medium bending rate of fiber.

④Non-bending fabric (multiaxial cloth): medium covering performance, no bending of the fiber.

Carbon fiber prepreg process

• 1. Solvent-based process

Only suitable for the preparation of fabric prepreg.

• 2. Two-step hot melt prepreg process

(1) Resin film preparation

(2) Immersion

The one-step hot-melt prepreg preparation process

The hot-melt process is the mainstream process for the production of carbon fiber prepreg.

The two-step method is popular in 90% of the country.

Application of carbon fiber prepreg

1. Vacuum bag high-temperature curing process

• Aerospace
• Wind power field
• Shipbuilding industry
• Auto industry
• Rail transit interior parts

2. Autoclave process

• High-quality composite products
• Structural parts

3. Prepreg molding process (PCM process)

4. Prepreg tape coiling process/prepreg wire winding process

• Fishing rod
• Golf clubs
• Ski poles
• Pipeline
• Pressure vessel

The choice of the manufacturing process is based on the three factors of product category and customer requirements for quality and cost.

Prepreg fiberglass

Glass fiber prepreg is a new type of material made of epoxy resin or phenolic resin as the matrix and immersed reinforced glass fiber filaments in the matrix.

It is an essential raw material for preparing composite materials.

Glass fiber prepregs are widely used in industrial fields and are the most widely used and cheapest composite fabrics.

The product is relatively light in weight, moderate in tensile strength and compressive strength, easy to operate, can effectively improve strength, hardness, and corrosion resistance, enhance wear resistance and impact resistance, and increase service life.

According to different prepreg resins, glass fiber prepreg products are mainly divided into epoxy resin system prepreg and phenolic resin system prepreg.

In the Chinese market, the epoxy resin system prepreg accounted for 58.31% of the total in 2018.

In 2019, the consumption of epoxy resin system prepreg is expected to be 29.69 million square meters, compared with 24.26 million square meters in 2014, the annual growth rate of the product consumption is 4.12%.

Glass fiber prepreg is relatively environmentally friendly, but it is necessary to avoid direct skin contact with such materials.

There is a layer of the wetting agent on the glass fiber’s surface, the main ingredients are some coupling agents, epichlorohydrin, water repellent, etc.

These chemicals may cause skin allergies, dermatitis, and pimples.

The resin of the glass fiber prepreg is mostly epoxy resin, and the curing agent is generally acid anhydride or amine, which has certain irritation to the skin and mucous membrane.

Is Fiberglass bulletproof?

There is no doubt that glass fiber is a kind of bulletproof material.

Since World War II, composite materials have shown many advantages in armor applications.

Nowadays, due to the increase in various regional conflicts and criminal activities around the world, the market for bulletproof materials is growing.

Composite materials have played a greater role in this industry.

From bulletproof vests for soldiers to armor plates for vehicles to explosion-proof systems for infrastructure, reinforced plastics all show the advantages of lightweight and long service life.

These bulletproof and explosion-proof materials use various reinforcing fibers, such as aramid fibers, ultra-high molecular weight polyethylene fibers (Spectra, Dyneema), and M5 fibers.

The glass fiber (S glass and E glass) also performed well.

Although glass fiber is considered to be the heaviest fiber among bulletproof materials, it has a lower price and a wider supply.

It also occupies a unique position in the composite armor market.

American ACY is the only manufacturer in the world that produces S-2 high-strength glass fiber.

S-2 High-strength Glass Fiber

According to ACY, S-2 fiber has comprehensive properties such as tensile strength, compression resistance, high rigidity, and fatigue resistance, and can play the dual role of bulletproof and construction in composite products.

The company entered the bulletproof armor market in the 1980s.

It uses S-2 glass non-twisted roving to reinforce phenolic resin to make the HJ1 hard armor plate.

S-2 glass non-twisted rental gauze has a high energy absorption capacity, and phenolic resin does not burn when exposed to fire, so the armor system can not only block missiles but also has excellent fire, smoke, and poison resistance.

Solvent-based prepreg

Solvent-based process: the reinforced fiber material is drawn into the resin solution tank by the NIP roller, and then immersed in the resin, and then heated in the oven.

After the oven is heated, the release paper or PE film is coated, and finally, rewound to become the prepreg jumbo roll.

The process is shown in the figure below:

Is carbon fiber stronger than fiberglass?

In order to better compare the strength of carbon fiber and glass fiber, a carbon fiber fishing rod and a glass fiber fishing rod were used for comparison.

Carbon Fiber Fishing Rod

Carbon fiber rods, also called carbon rods, have been produced and used in China since the 1990s.

Carbon fiber rods are more superior to glass fiber rods.

Carbon fiber poles of the same length are 50% lighter than glass fiber poles.

A 5.4-meter-long carbon fiber rod weighs only about 300 grams, and the rod body is much thinner than a glass fiber rod.

In the past two years, the use of carbon fiber rods has become very popular, and most anglers use carbon fiber rods.

The carbon fiber rod is made of high-tech material-carbon fiber.

This material is characterized by high strength, heat resistance, lightweight, and corrosion resistance, but it will conduct heat and electricity.

Another shortcoming is that the texture is relatively brittle, and the toughness is not as good as the glass fiber rod.

If you encounter thunderstorms while fishing, lightning strikes are prone to accidents, anglers must pay more attention.

In order to prevent the carbon fiber rod from conducting electricity when in use, you can buy an anti-electric grip cover at the fishing tackle shop, put it on the pinch part, and heat the outside of the cover with an alcohol lamp to make the rubber sleeve and the rod stick firmly bonded.

The main material of fiberglass rod is a chemical material called fiberglass.

Fiberglass poles are lighter than bamboo poles, are not afraid of water, are corrosion-resistant, and are not easy to break and deform.

Most anglers now use pull-out hollow fiberglass rods with different lengths, making them economical fishing rod.

This pole is characterized by good toughness and sturdiness, but the length is usually less than 10 meters.

The weight of fishing rod is heavier than the carbon fiber rod, and its outstanding feature is that it is not conductive and safe to use.

Generally speaking, carbon fiber composite materials have more performance advantages than glass fiber composite materials, but it does not mean that glass fiber materials are useless.

First of all, glass fiber materials are more advantageous in terms of price.

In areas where technical requirements are not very high, the first consideration may be glass fiber materials.

The glass fiber material has good insulation performance, non-conductivity, and good wave permeability;

Carbon fiber composite materials have good electrical conductivity and good electromagnetic shielding properties.

Although they have advantages and disadvantages, they also determine the applicability of the two in the field.

Which materials should be used, or should be decided according to one’s own technical requirements and budget.

Is Kevlar stronger than carbon Fibre?

Compared with traditional glass fiber, Young’s modulus of carbon fiber is more than 3 times;

Compared with Kevlar fiber, Young’s modulus of carbon fiber is about twice that, it is insoluble in organic solvents, acids, and alkalis, and has outstanding corrosion resistance.

In terms of strength, the strength of carbon fiber is similar to that of Kevlar, but their softness is different.

Kevlar is softer and comfortable to wear;

Carbon fiber is very hard, but very light, so F1 cars and others use carbon fiber to build the body.

If you do armor, I personally think carbon fiber is better.

What type of material is Kevlar?

Kevlar fiber is a material with good performance and has been widely used in bulletproof materials.

But for a combat soldier, the most difficult parts to protect are the hands, neck, knees, and elbow joints.

Because these parts can be bent, it is difficult to effectively protect them with traditional bulletproof materials.

According to reports, several companies, mainly Armor Holdings, have collaborated to develop a new type of ballistic protection material.

Because this material is filled with super-hard Kevlar fiber nanoparticles, it is similar to a liquid material, and is extremely convenient to use, and has the excellent protective properties of traditional ballistic materials.

The researchers said that by adding super-hard Kevlar fiber nanoparticles to a liquid that cannot be evaporated, this unique “liquid” ballistic material is obtained.

When a high-energy mechanical strike occurs, the structure of the solution changes and the Kevlar nanoparticles instantly become clusters of atoms, becoming a strong solid component.

This phase transition takes less than milliseconds, so it can protect against cold weapons and bullets.

Relevant experts pointed out that at room temperature, this material is like an ordinary liquid, so it can be used for civilian purposes, such as:

• Rescue
• Fire protection
• Automobile safety protection

It is reported that the American Armor Holdings Corporation has applied for a patent for the scientific research achievement and plans to put this material into mass production by the end of this year.

Is Kevlar stronger than fiberglass?

Compared with glass fiber, Kevlar fiber is lighter in weight and stronger.

The tensile strength of “Kevlar” is extremely high, more than twice that of nylon fiber.

Its appearance has significantly improved the protective performance of body armor.

Tests show that the ability of “Kevlar” to absorb the kinetic energy of shrapnel is 1.6 times that of nylon and twice that of steel.

The multilayer “Kevlar” fabric also has a good protective effect on bullets.

Because “Kevlar” is light in weight and good in elasticity, it is favored by the army and police of many countries and is also used to make helmets.

China began to develop and produce “Kevlar” helmets in the 1980s.

Compared with FRP, under the same protection situation, the use of “Kevlar” material can reduce the weight by half.

And the toughness of the “Kevlar” laminated sheet is three times that of steel, and it can withstand repeated impacts.

The combination of the “Kevlar” sheet and steel armor is extremely powerful.

If the aramid fiber composite armor is used, it can prevent anti-tank missiles with an armor-piercing thickness of 700mm and can also prevent neutron bombs.

What is the strongest composite material?

Among all composite materials, carbon fiber composite materials are the strongest.

Carbon composite materials have very high strength and extremely strong resistance to tension.

They are widely used in the aerospace field.

Carbon fiber composite materials are also used in the nose cone of intercontinental ballistic missiles.

Prepreg PCB

Printed circuit boards (PCBs) are usually flat laminated composite materials made of non-conductive substrates, with copper circuit layers embedded on the internal or external surfaces.

They can be as simple as one or two layers of copper, or in high-density applications, they can have fifty or more layers.

The flat composite surface is ideal for supporting components that are soldered and connected to the PCB, while copper conductors connect the components to each other electronically.

The basic components of standard printed circuit boards include prepreg, laminate, copper foil, solder mask, etc.

The prepreg sheet is a material used to bond PCBs together.

The prepreg sheet is critical in PCB manufacturing, and it is also a material used to build PCB laminates.

Laminates (sometimes called copper clad laminates) consist of prepreg sheets that are laminated together under heat and pressure, with copper foil on each side.

After the resin hardens, the PCB laminate is like a plastic composite material with copper foil on both sides.

We imaged and etched away the copper foil to create a circuit on the surface of the laminate.

These copper circuits will become conductors or wires on the inner and outer layers of the circuit board.

After imaging and etching the stack with circuits, you can use prepreg to stack them together.

The solder resist is a green epoxy coating that covers the circuit on the outer layer of the circuit board.

The internal circuit is buried in each layer of the prepreg, so there is no need to protect it.

However, if left unprotected, the outer layer will oxidize and corrode over time.

The solder mask layer provides protection for the conductors outside the PCB.

The nomenclature, sometimes called screen printing, is the white letters you see on top of the solder mask on the PCB.

The term is the letter that shows the position of each component on the board and sometimes provides the component orientation.

In addition to green and white, other colors can be used for solder masks and nomenclature, but white is the most popular.

Solder resist can protect all circuits on the outer layers of the PCB, and we do not plan to install components on these outer layers.

But we also need to protect the exposed copper holes and pads in order to solder and install components on these pads.

In order to protect these areas and provide good solderable surface quality, we usually use metal coatings such as nickel, gold, tin/lead, silver, and other final surface coatings designed only for PCB manufacturers.

Prepreg carbon fiber suppliers

The world-renowned carbon fiber prepreg suppliers include:

• Celanese
• Cytec Solvay Group
• MRC
• Teijin
• Toray
• American Hexcel
• Taiwan Formosa Plastics

I have summarized a list of suppliers of carbon fiber prepreg and composite materials, please check the following pictures:

Prepreg carbon fiber weight

The weight per unit area of carbon fiber prepreg tape is relatively light.

Based on the weight per unit area of carbon, the grammage of carbon fiber prepreg tape is generally 150gsm to 600gsm.

Prepreg carbon fiber price

In China, the price of carbon fiber prepreg is sold in square meters, and the price per square meter ranges from 40RMB (USD$6.06)-165RMB (USD$25).

Prepreg Manufacturing Process

What is prepreg tape?

Continuous fiber-reinforced thermoplastic unidirectional prepreg tape (UD Tape) is a sheet-shaped composite.

Unidirectional continuous fibers parallel to each other after being impregnated with the molten thermoplastic resin (PE, PP, PA, etc.), such a process is a melt impregnation process.

Fiber types:

• Glass fiber
• Aramid fiber
• Carbon fiber

Resin types:

• Polypropylene (PP)
• Polyethylene (PE)
• Nylon (PA)

Sheet thickness: 0.15mm-0.40mm;

Sheet density: 250gsm-620gsm;

Sheet width: 0mm-650mm;

Color:

• Normal natural color
• black
• Other customizable colors

Advantages:

• 1. High specific strength and specific stiffness;
• 2. Good impact resistance;
• 3. Acid and alkali resistance, environmental protection, no VOC/formaldehyde emission, recyclable;
• 4. Flexible design according to usage requirements, short product development cycle;
• 5. Suitable for a variety of processing and manufacturing processes, including molding, thermal compounding, thermal welding, an adhesive connection, cutting, and other processing methods.

How is prepreg made?

There are many ways to make prepreg, and the most popular one is the thermoplastic resin hot melting method.

The following figure shows the process of making prepreg by the thermoplastic resin hot melting method.

This method is very popular with foreign suppliers of the prepreg production line.

After being unrolled from the creel, the fiber yarns merge with the carrier paper and the release paper and enter the heated calender roll together.

After being heated and melted by the heated calender roll, the fiber yarns will be fully impregnated with the coated resin on the release paper.

The fiber yarns will also stick together.

After coming out of the heated calender roll, it becomes a sheet-like prepreg material that moves forward continuously and then is wound into a prepreg jumbo roll through the winding station.

What are the types of manufacturing methods for composites?

The manufacturing methods of metal matrix composites are roughly divided into three types:

Solid-state method:

The solid-state method is a method in which the base metal is in a solid-state and mixed with reinforcing materials to form a new composite material. It includes:

• Powder metallurgy method
• Hot pressing method
• Hot isostatic pressing method
• Rolling method
• Extrusion and drawing method
• Explosive welding method

Liquid method:

The liquid method is a method in which the base metal is mixed with reinforcing materials to form a new composite material when the base metal is in a molten state. It includes:

• Vacuum pressure impregnation method
• Squeeze casting method
• Stirring casting method
• Liquid metal impregnation method
• Co-spray deposition method
• In-situ reaction generation method

Surface composite method:

• Physical vapor deposition method
• Chemical vapor deposition method
• Thermal spray method
• Electroless plating method
• Electroplating method
• Composite plating method

The production process of resin-based composite materials mainly includes the solution method and the hot-melt method.

• Solution method

Dissolve the resin in a solvent with a low boiling point to form a solution with a specific concentration.

And then impregnate the fiber bundle or fabric into the resin solution at a specified speed, control the resin content with auxiliary tools, and then dry it, volatilize the low-boiling solvent, and finally wind up.

• Hot melt method

Under certain pressure and temperature, the resin film and the corresponding fiber or fabric that meet the requirements are hot-pressed and impregnated through a hot-melt spreading machine, and the material produced is a hot melt prepreg.

Its advantage is that the resin content is controllable, and the prepreg of the specified weight can be produced.

This method is generally used in actual production.

At present, many high-performance products use carbon fiber composite materials as structural components.

The strength and durability of carbon fiber composite materials depend on the characteristics of carbon fiber prepregs.

Different types of prepregs are used in different fields.

At present, China’s research in this area has also made significant progress.

The well-known carbon fiber composite materials are made of carbon fiber prepreg through a series of molding processes, and carbon fiber products have also been used in many fields.

Prepreg manufacturing process PPT

The manufacturing process of prepreg is as shown in the figure below.

After being unwound from the warp creel, the fiber yarn enters the resin tank to impregnate the resin, and the resin-impregnated fiber yarn enters the oven for baking and then is coated with a compaction roller.

The prepreg is finally wound into a prepreg mother roll on winding station.

You are welcome to send us an inquiry on this website, and we will send you the beautifully made PPT of the prepreg production process.

Autoclave composite manufacturing PDF

1. Introduction

Autoclave forming technology is currently one of the widely used forming methods for advanced aerospace composite material structures and is mainly used for the manufacturing and forming of large-scale composite skin panels, ribs, frames, etc.

In the process of autoclave molding, many factors affect the final molding dimensional accuracy at different levels, such as:

• The geometric dimensions
• Material properties
• Layer design
• Curing molding process parameters
• Tooling design of composite components

Finally, it increases subsequent assembly and manufacturing costs.

In order to overcome this difficulty, the traditional solution is to determine the curing process parameters of the structural parts.

Parameters are determined on the basis of trial and error and to compensate by modifying the molding profile.

Due to the many influencing factors, the use of experimental methods to determine process parameters has certain limitations.

Analyzing the effects of various factors on the molding quality through numerical simulation methods, and then selecting reasonable process parameters, is of great significance to saving test costs and shortening the development cycle.

2. Simulation of curing molding process based on Simcenter 3D platform

During the composite material component’s curing and molding process in the autoclave, due to the temperature distribution change in the tank and the resin curing reaction’s exothermic effect, temperature gradients and residual stresses will inevitably occur inside the component.

This finally leads to component deformation and natural defects.

The composite materials’ curing process can be roughly divided into the following three stages:

• (1) Resin flow stage

The resin has not yet cured, and the material is in a viscous flow state;

• (2) Resin heating and curing stage

At the beginning of resin curing, the resin gradually transforms from a viscous fluid state to a glass state, the resin matrix modulus increases, and the volume shrinks, and the material exhibits viscoelastic behavior.

At this stage, due to the existence of temperature gradient, the degree of curing is different in different positions, which is the root cause of curing deformation;

• (3) Cooling and demolding stage

In the fully cured stage, the material exhibits elastic behavior.

Based on Simcenter 3D, Siemens has launched a complete composite material forming process simulation solution, covering the entire process:

• Coupling analysis of complex heat flow in an autoclave;
• Analysis of fiber placement on the mold;
• Thermochemical analysis during the molding process of composite materials;
• Thermal structure nonlinear finite element analysis capabilities.

Composite material manufacturing process simulation solution

3. The theoretical background of Simcenter 3D curing analysis

The composite materials curing is a complex process involving multiple physical phenomena at the same time:

The gas flow in the tank, the thermochemical reaction of the part itself, the structure is subject to vacuum negative pressure, auxiliary materials, and mold constraints in the entire process of engineering.

This process involves disciplines such as:

• Fluid mechanics
• Thermochemistry
• Mechanics

Schematic diagram of advanced composite material autoclave curing forming process

If these issues are considered at the same time when modeling, the whole model will be very complicated.

In the Simcenter 3D analysis process, it is decoupled and simplified.

• 1st step

Use the heat flow analysis of the autoclave to calculate the external thermal boundary conditions of the part in the entire process;

• 2nd step

Use thermochemical analysis to obtain the temperature field, curing degree field, and glass transition temperature field of the material itself;

• 3rd step

Structural finite element analysis, using the calculation results of the previous step to determine the mechanical properties of the resin, then considering that the fiber’s physical properties during the curing process are basically not affected, and a single layer is obtained by homogenization.

Then, combining the mechanical properties of the entire composite material component, and integrating the external thermal boundary conditions of the 1st step’s part and its own constraints.

The residual stress and solidification spring back analysis of the structure is performed.

For detailed PDF files, please send us an inquiry on this website, our Jota sales will contact you in time and send the PDF files to you.

Prepreg is manufactured by which process?

Prepreg, also known as molding compound, is a resin matrix impregnated with continuous fibers or fabric under certain conditions to make a resin matrix and reinforcement mixed composite.

It is an essential intermediate material for making composite materials.

Certain properties of the two different materials greatly enhance the performance of composite materials, and prepreg is a structural unit with certain mechanical properties.

The quality of prepreg is directly related to the quality of composite materials, so prepreg is of great significance to the application and development of composite materials.

With the emergence of high-performance reinforcing fibers such as carbon fiber, aramid, etc., prepregs have slowly been valued and have made considerable progress.

The continuous improvement of the performance of reinforced carbon fiber has also promoted the research and development of prepregs.

At the same time, the process technology is becoming more mature and the scope of use is also expanding.

At present, most of the carbon fiber is applied in the form of prepreg.

In recent years, the emergence of new high-performance thermoplastic resins has improved certain properties of composite materials.

However, due to its high melting point and high melt viscosity, there is no suitable low boiling point solvent to dissolve, which brings a series of problems to the manufacturing of prepregs.

The raw materials of the prepreg include reinforcement and matrix.

The reinforcements for prepreg are mainly carbon fiber, aramid, glass fiber, and their fabrics.

The resin matrix for prepreg includes thermosetting resin and thermoplastic resin.

As a prepreg reinforcement material, it usually has high strength and high modulus, high elongation at break, and the dispersion of performance as small as possible, and the linear density of the fiber or the surface density of the fabric should be stable.

The resin bond must have better interface properties.

In addition, after the fiber is sizing, the sizing agent has good compatibility with the matrix resin.

On the premise of ensuring other properties, the sizing agent content is controlled at about 1% to facilitate dipping.

Unidirectional prepreg should be twistless or untwisted fiber, which is good for dispersing fiber during dipping.

• The solution impregnation method requires the resin matrix to be dissolved in commonly used low-boiling solvents;
• The direct hot melt method requires the resin matrix to have a low melting temperature and a lower viscosity after melting;
• The film calendering method requires good film-forming properties of the resin matrix;
• The powder method requires that the particle size of the resin matrix powder be uniform and the diameter is preferably smaller than the diameter of the reinforcing fiber.

How do you cure carbon fiber?

Carbon fiber composite material has excellent properties such as:

• Low density
• High specific strength
• High specific modulus
• Wear resistance
• Small thermal expansion coefficient
• Good dimensional stability

It is a lightweight, high-performance structural and functional material.

It is used in many fields:

• Aerospace
• Weapon equipment
• Communication satellites
• Transportation
• Marine engineering
• Construction machinery
• Wind power generation
• Fitness equipment
• Other fields that have broad application prospects

Two-dimensional carbon fiber reinforced resin matrix composites can ensure that the composite materials have consistent performance in the two-dimensional fiber direction;

And it can overcome the limitation of one-dimensional (unidirectional) carbon fiber reinforced resin matrix composites that only have superior performance in a single fiber direction.

Research and application are increasing widely.

However, the gaps between the two-dimensional woven carbon fibers are small and uneven, and the produced composite material has a high fiber volume fraction, which makes it very difficult to achieve sufficient and uniform impregnation.

At present, the production of two-dimensional woven carbon fiber reinforced resin-based composite materials mainly includes:

• Handy lay-up
• Compression molding
• Lamination

But the handy lay-up method cannot provide high resin impregnation pressure and vacuum environment.

And the interior of the produced composite material is easy to leave defects such as pores and holes, and the molding and lamination methods are relatively complex, difficult to automatically pick up parts, and cannot provide a vacuum environment.

The combined method of vacuum impregnation and thermo-compression molding can provide high vacuum and ensure high impregnation and curing pressure.

It becomes one of the effective methods for producing two-dimensional woven carbon fiber reinforced resin matrix composites with ideal properties.

How do you prepreg carbon fiber?

Please look at the following two pictures.

The first is a schematic diagram of dry prepreg fiber making, and the second is a schematic diagram of wet prepreg fiber making.

These two methods have their own advantages and disadvantages.

You can refer to the tips on these two pictures.

How do you make carbon fiber?

Because the carbonization yield of PAN-based carbon fiber can reach 45%, which is higher than other raw materials.

And the industrial process is simple, easy to operate, and the conditions are easy to control, the cost is relatively low, especially its mechanical properties, such as tensile strength, the modulus of elasticity is very good.

It is currently the most widely used carbon fiber.

PAN-based carbon fiber production process

• 1. Spinning

Polyacrylonitrile is dissolved in a water solvent to prepare a 15% spinning solution.

The water solvent is generally sodium thiocyanate or nitric acid, dimethyl sulfide, etc.

PAN precursor can be obtained through spinning processes such as wet spinning or dry jet spinning.

The prepared PAN raw yarn is woven into cloth in a knitting machine, and then sent to a pre-oxidation processor for pre-oxidation treatment.

• 2. Pre-oxidation treatment

The pre-oxidation treatment is carried out in two stages.

The polyacrylonitrile fiber cloth is first catalyzed by a catalyst and then oxidized with air (or oxidation) for 10-30 minutes at 200-220°C and under proper tension;

And then it is heated and continue to receive oxidation treatment for 30-100min at 220-330°C and under proper tension conditions, so that the color of the fiber gradually changes from white to yellow, and finally turns to copper brown.

The waste gas generated in the pre-oxidation treatment is discharged from the waste gas treatment device, and the treated fibers are sent to the carbonization processor for carbonization treatment.

• 3. Carbonization treatment

The carbonization process is carried out under the protection of pure ammonia gas flow (or vacuum), after low-temperature carbonization (300-1000℃) and high-temperature carbonization (1000-1800℃), it is transformed into carbon fiber with chaotic layer structure.

The ammonia hydrogen decomposition gas and the carbonization decomposition gas generated during the carbonization process are successively discharged from the carbonization treatment device, and the carbonized fiber is sent to the graphite processor for processing.

• 4. Graphitization treatment

During graphitization, carbon tube furnaces are used for intermittent production, or current can be passed through the fiber, and the fiber’s own conductivity can be used to generate heat for continuous processing.

The graphitization process is carried out under the protection of inert gas (argon), and the graphitization is drawn under the high heat treatment temperature of 2000-3000℃.

The carbon fiber obtained by the graphitization treatment is subjected to a non-damage inspection, and the solution is soaked with a dilute epoxy resin, so that the obtained unidirectional knotless carbon fiber cloth has good lateral adhesion and is convenient for operation.

The treated carbon fiber enters the solvent dryer to evaporate the solvent, and then undergoes no damage inspection to obtain the finished carbon fiber.

Why is carbon fiber so expensive?

Carbon fiber is a thing that people love and hate.

Not only can it be stronger than steel, but it is also much lighter than steel in terms of weight.

For example, in the automotive field, carbon fiber material has become necessary equipment for supercars that pursue performance.

With the advancement of technology, the application of carbon fiber materials has become more and more extensive.

At present, even ordinary cars have begun to use a large number of carbon fiber mixtures.

Even so, the price of products containing carbon fiber materials is very high, and there is still a long way to go before widespread use.

So, why are carbon fiber materials so expensive?

From the composition point of view, carbon fiber is a material with a carbon content of more than 95%, which is not much different from the charcoal burned at home, but its structure is completely different from that of charcoal.

This material is made by stacking organic fibers such as flake graphite crystallites along the fiber axial direction and then carbonizing and graphitizing.

In other words, this is an inorganic material manufactured entirely by manual intervention.

Simply put, carbon fibers can be made by carbonizing polyacrylonitrile fibers, pitch fibers, viscose fibers, or phenolic fibers.

The raw materials are different, the carbon fibers produced are also completely different.

Among them, the high-performance carbon fiber made from polyacrylonitrile fiber yarn has a simpler production process than other methods.

The output accounts for more than 90% of the global carbon fiber output.

It is composed of the original yarn or roving based on structural reinforcement requirements.

What can carbon fiber be used for?

Carbon fiber has many excellent properties, such as:

• High strength
• High modulus
• Low density
• No creep
• Ultra-high temperature resistance
• Low thermal expansion coefficient, anisotropy
• Good corrosion resistance

With so many excellent properties, carbon fiber materials are widely used in various fields, such as:

• High-end fields
• Spacecraft (electromagnetic shielding)
• Automobiles (sports cars)
• Medical equipment (corrosion resistance)
• Bridges and tunnels (high strength)
• Fishing rods
• Rackets

They are mainly for civilian use.

Why is carbon fiber so expensive?

• 1. The production cost of carbon fiber is high

First of all, the production of carbon fiber is a very complex and systematic process.

From the preparation of the raw yarn to pre-oxidation, carbonization, graphitization, to sizing, encapsulation, and finished products, each step of the production process has high requirements and requires high precision control.

And the requirement for equipment is quite high. The high initial equipment investment and maintenance cost are some of the reasons for the high price of carbon fiber.

Secondly, the production of carbon fiber is still an energy-intensive process.

Especially for later carbonization and graphitization, a very high temperature is required, and the high energy consumption in the production process is another reason for the high cost of carbon fiber.

• 2. The price of carbon fiber yarn is relatively high

Carbon fiber is “woven”.

However, the method of making this material is indeed the same as knitting a sweater, which is woven.

It’s just that the additives and weaving methods of various manufacturers are different, resulting in different properties of carbon fiber.

For example, the Lamborghini we often mentioned, the carbon fiber material used in it is woven from the short fiber.

This material is more uniform in force, and its strength and toughness are very large.

Since carbon fiber is a “woven” material, of course, it cannot lack raw materials.

That is, “weaving” the “wool” of carbon fiber materials, we call it “raw yarn”.

This kind of raw yarn needs high strengthening, densification, and high purification requirements.

Due to the high manufacturing cost, the price of raw yarn remains high.

Because having a good raw yarn is the first task to make high-strength carbon fiber materials.

• 3. Technology blockade and market monopoly

The high price of carbon fiber is partically because carbon fiber is still in the seller’s market.

As a new type of material, carbon fiber has very high manufacturing costs and requirements.

And in different fields, have different requirements for carbon fiber performance.

Some areas focus on high strength, while others focus on heat resistance.

This has caused great difficulties for carbon fiber manufacturers.

For now, the latest carbon fiber material is T1000.

This type of material’s manufacturing technology has been monopolized by the United States and Japan.

However, China can only develop carbon fiber materials of T300 and T800 through its own efforts.

As the core technology of high-end products is still controlled by developed countries, Japan and the United States, the production capacity is limited and the demand has increased greatly, resulting in high carbon fiber prices.

Hot Melt Prepreg Production Line

How to make prepreg?

There are two methods for making prepreg: dry method and wet method.

The dry method is divided into the powder method and hot melt resin method (the latter is also called the hot melt method).

Powder prepreg refers to a composite in which the resin powder adheres to the fiber, and after partial melting, the resin is discontinuous, and the fiber is not fully saturated by the resin.

Comparing the composite materials made of dry prepregs and wet prepregs, the former generally looks better, and the control accuracy of the resin content in the material is higher.

As far as the current advanced composite materials for aviation are concerned, the damp and heat stability of the hot-melt composite materials is often better than that of the solution-based composite materials:

The same is boiled in boiling water for 48 hours, and the mechanical properties of the former (such as flexural modulus and strength, the retention rate of interlayer shear strength, etc., especially the retention rate of high-temperature mechanical properties, is significantly higher than the latter.

Prepreg production process

• 1. Add a certain proportion of alcohol through barium phenolic resin, put it in a mixer, and stir.

The stirring speed should not be too fast, and it should be controlled below 100 revolutions per minute.

The mixing time is about 30-60 minutes, and then use a hydrometer to measure the specific gravity (it is appropriate to control it between 1.07 and 1.09), and put it in a small bucket for use after mixing.

• 2. Heat the glass fiber cloth in a dewaxing furnace for dewaxing, and then take it up for use after dewaxing.

• 3. Start the equipment to preheat, and set the oven temperature to 95-120℃.

The specific temperature depends on the season, indoor temperature, and humidity.

It mainly depends on whether the volatile content is too large or too small.

Next, set the unwinding tension and rewinding tension.

• 4. After the temperature rises to the specified temperature, the furnace temperature needs to run for half an hour to make the indoor temperature reach the saturation state before it can run.

Otherwise, the temperature in the furnace is likely to be affected by the fluctuations introduced by the glass cloth, making it difficult to control the volatile content, resulting in defective products.

• 5. Use a feeler gauge to measure the gap between the two groups of rubber rollers.

The gap between the first group of rubber rollers should be adjusted to 0.25mm, and the gap of the second group of rubber rollers should be adjusted to 0.30mm.

• 6. Put the dewaxed glass fiber cloth into the unwinding device, pass the glass cloth through the cloth storage rack into the first group of dipping tanks, and then into the second group of dipping tanks, and put the squeezing roller down.

• 7. Pour in the prepared glue.

The amount of glue is about 75~100Kg per glue tank.

It is best to add it while using it.

This can control the volatile content of alcohol in the glue tank, keep the glue’s specific gravity stable, and control the glue content’s fluctuation error to the minimum.

• 8. Introduce the cloth guide into the oven and connect with the glass cloth, and the cloth guide’s head is rolled on the winding station’s paper tube.

After the cloth is guided into the oven and led to the winding station, the cloth guide separate from the glass cloth and removes the guide cloth for next use.

• 9. After the whole line is running, control the running speed at no more than 3m/min.

After the glass cloth head comes out, it is tested according to the phenolic prepreg online inspection method.

Whether the resin content and volatile matter meet the technical requirements, the production can be continued after being qualified.

• 10. The specific gravity and furnace temperature of the glue liquid should be monitored in real-time during the production process.

Each roll of prepreg is required to be tested online at least once, and the test results are recorded and archived in order to prepare for product traceability and an important basis for process improvement.

• 11. When connecting two rolls of glass cloth, first put down the length storage press roller, and connect the tail of the glass cloth to the next glass cloth’s head with a manual sewing machine.

After the connection is strong, tighten the glass cloth to add unwinding tension and lift.

Just lift the press roller of the length storage device.

• 12. When the glass cloth joint enters the squeeze roller above the glue tank, the squeeze roller should be lifted to prevent the glass cloth from being too thick at the joint to cause the glass cloth to break and fail to operate normally.

When the joint reaches the several NIP rollers at the bottom of the oven, it should be carefully observed to prevent the glass cloth from breaking due to excessive stretching force and failing to operate normally.

• 13. After the joint reaches the rewinding position, the wrinkles on the left and right from the joint should be removed before sampling and testing.

• 14. When rewinding, use 3″ paper tubes, with double-sided tape wrapped around the surface for use in the next process.

When rewinding, the glass cloth has burrs on both sides, and the burrs are thicker than the cloth.

The accumulation of a certain degree will easily deform the cloth surface, so the burrs on both sides should be cleaned up in time.

Both sides should be neat when winding, otherwise, it will cause more waste during slitting.

• 15. After the product has passed the test, put it tightly in a moisture-proof bag and put it in a ventilated and dry place, with the production date on the surface, and wait for cutting.

• 16. Load the qualified prepreg glass cloth into the slitting machine and slit it according to the size required by the technology.

The slitting tolerance is ±2mm, and it is strictly forbidden to use any solvent during slitting.

• 17. Vacuum packaging should be done in time after slitting, and direct contact with hands is forbidden during packaging to prevent excessive moisture from affecting the product’s volatility.

• 18. After packing, put it in the packing box.

The products in the box must conform to the slitting specifications posted outside the box, and the products shall be stored in cold storage after passing the inspection.

Prepreg processing

Different molding methods can be used for prepregs, and a more suitable molding method can be selected according to different applications.

The prepreg molding process mainly includes the vacuum bag process, autoclave process, molding process, tube rolling process, pultrusion forming process, roll forming process, winding forming process, pressure bag process, etc.

• The vacuum bag process is mainly used in the decoration of the shipbuilding industry railway system;
• The autoclave process is mainly used in high-quality composite materials;
• The molding process is mainly used in flat panels, sporting goods, sleds, and industrial products;
• The tube rolling process is mainly used in fishing poles, ski poles, golf clubs, and pipe fittings;
• The pressure bag process is mainly used in masts, antenna poles, and various pipe fittings.

1. Vacuum bag process

The vacuum bag molding process is a molding process in which the product is sealed between the mold and the vacuum bag, and the product is pressurized by vacuuming so that the product is more compact and has better mechanical properties.

Advantages:

• 1. High fiber content, better mechanical properties of the product;
• 2. Uniform pressure, uniform product performance;
• 3. Effectively control product thickness and glue content;
• 4. Reduce bubbles in the product;
• 5. Complicated and large parts can be formed;
• 6. Reduce the damage to personnel caused by volatile matter.

Vacuum bag wet process:

• 1. Mold preparation, apply release agent
• 2. Product layering (hand lay-up, spraying, prepreg)
• 3. Spread the release cloth
• 4. Pave isolation film or isolation film with holes (may not be laid)
• 5. Spread air felt
• 6. Paste the sealing tape (can be advanced)
• 7. Sealing vacuum bag film
• 8. Install vacuum valve, quick connector, and vacuum tube
• 9. Connect the air source to check the vacuum
• 10. Vacuum and solidify the product
• 11. Product demoulding

2. Autoclave forming technology

Features:

Uniform pressure in the tank, fast, uniform air temperature in the tank, high precision, high quality, wide application range, suitable for batches, reliable molding process;

Disadvantages:

High cost and large initial investment.

3. Roll forming

Roll forming is mainly borrowed from metal forming methods.

The equipment consists of a series (one or more groups) of hot pressing rollers and cold pressing rollers.

After being heated, the paved prepreg is first passed through a set of hot rollers to deform the prepreg and then passed through a set of cold pressing roller for forming.

The pitch of such a cold pressing roller gradually shrinks.

Advantages:

• (1) The green body is compact, high in strength, and not easy to deform.
• (2) Low water content, smooth products, consistent product specifications.
• (3) High productivity and low labor intensity.
• (4) It is suitable for forming by male and female molds, the single machine connected.
• (5) The operation technology should not be very high to facilitate the formation of an automated production line.

According to the forming process, it is divided into male mold forming and female mold forming.

• ⑴Plastic mold forming

With a punch, the blank is used facing the model, and the roller head determines the outer surface of the blank. It is suitable for flat disc products (shallow products).

Advantages:

The belt mold is not easily deformed when it is dry (supported), the pattern and curved edges can be engraved on the use surface with the model, and it is relatively simple to take the blank and return the mold to the production line.

Disadvantages:

It is easy to deform and crack the blank when taking the blank.

• ⑵Internal mold forming

With a concave mold, the non-use surface of the blank faces the model, and the roller head determines the inner surface of the blank. It is suitable for bowls, cups, saucers, and small plate products (deep products).

Advantages:

No contact with the blank body when taking the blank, small deformation. The spindle speed can be higher and it is not easy to fly mud.

Disadvantages:

It is more complicated to return to the mold in the production line (turn over 180°).

4. Winding forming

Winding molding is a process in which the tension and winding angle are controlled by a winding machine, and the prepreg is wound on a core mold in a certain way to form a composite part by curing.

The winding molding process is only suitable for rotating tubular products.

The reinforcing materials used for winding molding are mainly various fiber yarns, such as:

• Alkali-free glass fiber yarn
• Medium-alkali glass fiber yarn
• Carbon fiber yarn
• High-strength glass fiber yarn
• Aramid fiber yarn
• Surface mat

For general civilian products such as pipes and tanks, unsaturated polyester resins are mostly used.

For winding products that require high mechanical properties, compressive strength, and interlayer shear strength, epoxy resin can be selected.

The inner mold for forming the hollow product is called the core mold.

Generally, the core mold must be released from the product after the winding product is cured.

The winding machine is the main equipment to realize the winding forming process.

The requirements for the winding machine are:

• ① It can realize the winding law of product design and the accuracy of yarn arrangement;
• ② Easy operation;
• ③ High production efficiency;
• ④ Low equipment cost.

Winding molding can be divided into:

• Dry winding
• Wet winding
• Semi-dry winding

Dry winding is to use pre-impregnated yarn or tape, which is heated and softened to a viscous fluid state on a winding machine, and then wound onto a core mold.

Wet winding is the process of dipping the fiber bundle (yarn-like tape) and then directly winding it on the mandrel under tension control.

The semi-dry winding method is to add a set of drying equipment to remove the solvent in the dipped yarn after the fiber is dipped into the core mold.

Compared with the dry method, the pre-gluing process and equipment are omitted;

Compared with the method, the bubble content in the product can be reduced.

Among the three winding methods, wet winding is the most common application;

Dry winding is only used in high-performance, high-precision cutting-edge technology.

Advantages of filament winding molding:

• ①The winding law can be designed according to the force condition of the product so that the strength of the fiber can be fully utilized;

• ②High specific strength: Generally speaking, compared with steel vessels of the same volume and pressure, filament wound pressure vessels can reduce the weight by 40-60%;

• ③High reliability: filament winding products are easy to realize mechanized and automated production.

After the process conditions are determined, the quality of the wound products is stable and accurate;

• ④ High production efficiency: mechanized or automated production requires fewer operators and fast winding speed (240m/min), so labor and production efficiency is high;

• ⑤Low cost: On the same product, several materials (including resin, fiber, and lining) can be selected reasonably, and then recombined to achieve the best technical and economic effects.

Disadvantages of winding molding:

• ①The adaptability of winding molding is small, and products of any structure form cannot be wound, especially products with concave surfaces, because the fibers cannot be close to the surface of the core mold and are overhead;

• ② Winding molding requires winding machines, core molds, curing furnaces, demoulding machines, and skilled technical workers.

It requires a large investment and high technical requirements.

Therefore, only mass production can reduce costs and obtain greater technology.

• The fiber content of the winding molding process can reach 60%-80%;
• The product thickness is 2-25mm;
• The maximum product diameter is 4m;
• The length is 12m;
• The curing temperature is 80-130℃;
• The molding cycle is determined by the product size;
• The molding pressure is determined by the tension of the winding machine.

The mold is a metal or plaster core mold with continuous production nature.

5. Compression molding

The advantages of compression molding are high production efficiency, easy to realize specialized and automated production;

High product dimensional accuracy, good repeatability; smooth surface, no secondary modification;

Can form products with complex structure at one time; mass production, low price.

However, the compression molding process is complicated in mold manufacturing, with high mold quality requirements, high molding pressure, large equipment investment, and limited by the press.

It is most suitable for the mass production of small and medium composite products.

Compression Molding Flow Chart

Due to the following factors, the molded products’ size gradually develops towards large-scale development.

• Continuous improvement and development of synthetic resin process performance, metal processing technology, press manufacturing level;
• Continuous increase of press tonnage and table size;
• Relative reduction of molding temperature and pressure of molded materials.

And compression molding can now produce large cars’ parts, bathtubs, integral toilet parts, etc.

The fiber content of the molded product is between 25%-60%, the thickness of the product is 1-10mm, the curing temperature is 40-50℃, cold pressing is 100-170℃.

The molding cycle is as short as 5-60min and the molding pressure is 10-40MPa.

The mold is generally made of steel, and the cold mold can be made of glass fiber reinforced plastic.

The product size is limited by the mold size and the tonnage of the press.

The production requires a hydraulic press, heating mold, cold mold, and other equipment, suitable for 100-20000T medium batch production.

6. Pultrusion process

Regarding the pultrusion molding process, is to form and solidify the prepreg under the action of traction force through an extrusion die, continuously produce FRP profiles with unlimited length.

This process is most suitable for the production of FRP profiles with various cross-sectional shapes, such as:

• Rods
• Tubes
• Solid profiles (I-shaped, trough, and square profiles)
• Hollow profiles (door and window profiles, blades, etc.)

The pultrusion process is composed of yarn feeding, dipping, pre-forming, curing and shaping, drawing, cutting, and other processes.

The advantages are:

• ①The production process is fully automated and controlled, and the production efficiency is high;

• ②The fiber content in the pultruded product can be as high as 80%.

The dipping is carried out under tension, which can generate the full potential of the reinforcing material and the product has high strength;

• ③The longitudinal and transverse strength of the product can be adjusted arbitrarily, which can meet the requirements of products with different mechanical properties;

• ④There is no corner waste in the production process, and the product does not need post-processing, so it saves labor, raw materials, and energy consumption compared with other processes;

• ⑤The product quality is stable, the repeatability is good, and the length can be cut at will.

The disadvantage of the pultrusion process is that the equipment investment is large, and the product shape is monotonous, only linear profiles can be produced, and the transverse strength is not high.

Among the raw materials for the pultrusion process, the most widely used resin matrix is unsaturated polyester resin, and the reinforcing material is mainly glass fiber and its related products, such as untwisted roving, continuous fiber mat, etc.

A mold is an important tool for pultrusion, and generally consists of two parts: a preforming mold and a forming mold.

• ① Pre-forming mold

In the process of pultrusion, the prepreg must pass through a pre-forming mold composed of a set of yarn guide elements before entering the forming mold.

The function of the pre-forming mold is to dip the reinforced material.

According to the profile section configuration form, gradually forms a preform with approximately the shape and size controlled by the molding die, and then enters the molding die, so as to ensure the uniform yarn content of the product section.

• ②Forming mold

The ratio of the forming mold’s cross-sectional area to the product’s cross-sectional area should generally be greater than or equal to 10, ensures that the mold has sufficient strength and rigidity, and the heat distribution after heating is uniform and stable.

The length of the pultrusion mold is determined by the pulling speed and the curing speed of the resin gel during the molding process, which ensures that the product reaches the degree of mold release and curing when the product is pulled out.

Steel is generally chrome-plated, and the surface of the mold cavity is required to be smooth and wear-resistant to reduce the frictional resistance during pultrusion and increase the mold’s service life.

The fiber content of the pultrusion process can reach 60%-75%, the profile thickness can reach 12mm, the bar diameter is 40mm, the curing temperature is 100-160℃, and it can be produced continuously.

The maximum traction force is 40 tons.

The mold is a pultrusion unit mold.

The size depends on the unit mold, and the length is not limited.

Prepreg slitting machine

The function of the prepreg slitting machine is to cut the prepreg mother roll with a width of 600-1500mm into narrow tapes with a width of 10 millimeters.

Such machines are usually divided into parts such as unwinding, web-feeding, slitting, rewinding, control, and waste discharging.

We, Jota, are the source factory specializing in the production of prepreg slitter machines.

Many large prepreg manufacturers in China are using our Jota prepreg slitting machines.

You are welcome to send us an inquiry on the website to inquire about the prepreg slitting machine.

Prepreg cutting machine

Carbon fiber prepreg cutting machine is suitable for cutting prepreg, carbon fiber, glass fiber, asbestos, graphite gasket, and other materials.

Advantages of carbon fiber prepreg cutting machine:

• Computerized intelligent automatic discharge, improve discharge efficiency, and material utilization;
• The whole equipment is welded, which greatly improves the cutting accuracy, and the cutting error is ±0.02mm;
• The tool speed can reach 2000mm/s, and efficiency is greatly improved;
• Automatic feeding module to realize automatic continuous cutting;
• Vacuum adsorption table, the material is fixed by vacuum adsorption during cutting to ensure cutting accuracy;

Prepreg cutting effect

Parameters of carbon fiber prepreg cutting machine:

Type: Vibrating knife cutting machine

Control method: CNC

Maximum engraving depth: <50mm

Positioning accuracy: ≤0.02mm

Current: AC

Fast forward speed: 200-2000mm/s

Voltage: 380V±10%/220V±10% optional

Maximum cutting speed: 2000mm/s

Rated power: 11kw

Repeat cutting accuracy: ±0.05mm

Scope of work: customized

Machine size: customized

Tools:

• Vibrating knife full cutting
• High-power active round knife
• Punching knife
• Pneumatic knife
• Multi-layer knife

Applicable materials:

• Glass fiber
• Glass fiber cotton
• Prepreg
• Carbon fiber
• Carbon fiber felt
• Boron fiber
• Aramid fiber
• Ceramic fiber
• Soft glass
• PVC
• Leather
• Sponge composite leather
• XPE material
• Silk ring footpad, leather
• Silicone
• Rubber materials
• Other composite flexible materials

Prepreg molding

Different molding methods can be used for prepreg, and a more suitable molding scheme can be selected according to different applications.

At present, our advanced composite materials business unit uses prepreg molding processes mainly including vacuum attack pressure process, autoclave process, winding molding process, and molding process.

Among them, the vacuum bag process is mainly used in interior parts such as vehicles, ships, and high-speed railways.

The autoclave process is mainly used in high-quality composite materials such as aerospace and military industries.

The molding process is mainly used in high-quality and high-precision military products such as flat plates and pipe fittings.

• 1. Vacuum bag process

The following is the process flow chart of the vacuum bag:

• 2. Autoclave forming process

The hot press weaving process is similar to the vacuum bag process, but because the pressure in the autoclave and the air temperature are uniform, high-precision and high-quality products can be produced.

The internal operating system of the autoclave

• 3. Molding process

Compression molding first put a certain amount of fiber prepreg into a metal pair mold and curing the molded product under a certain temperature and pressure.

The basic principle is: the thermosetting resins’ rheological behavior in the molding process is much more complicated than that of thermoplastics.

The entire molding process is always accompanied by chemical reactions, and the material exhibits a low-molecular viscous fluid state and fluidity during the initial heating stage.

Fortunately, as the functional groups react with each other, part of the cross-linking occurs, and the fluidity of the material gradually decreases, and produces a certain degree of elasticity, so that the material is in a gel state.

And then continues to heat to make the molecular cross-linking reaction more perfect, the degree of cross-linking increases.

The material changes from the gel state to the glass state, the resin body assumes a body structure, and the molding is over.

Advantages of the compression molding process:

• 1. The resulting product has small internal stress, is not easy to deform, and has good stability;
• 2. The product has high dimensional accuracy and good repeatability;
• 3. The surface is smooth and no secondary modification is required;
• 4. Products with complex structures can be formed at one time;
• 5. The wear of the mold cavity is small, and the maintenance cost of the mold is low.

The disadvantages of the molding process:

• 1. The initial investment cost is relatively high (metal mold, hot press, oven);
• 2. The mold’s temperature rising and falling time is longer;
• 3. High requirements for workers’ operating skills.

The molding process is widely used in:

• Industry
• Agriculture
• Transportation
• Electrical
• Chemical
• Construction
• Machinery

Because of the reliable quality of molded products, they have also been used in weapons, aircraft, missiles, and satellites.

Prepreg winding

The prepreg winding process does not use continuous prepregs but has a certain laminated design.

In our daily winding process, continuous prepreg can be used to produce pipes, gas cylinders, etc. through a certain angle design.

Therefore, the prepreg here is different from the traditional prepreg, and narrow prepreg tape is used.

Carbon fiber prepreg has obvious advantages and is widely used in:

• Fishing tackle
• Sports equipment
• Sporting goods
• Aerospace
• Other fields

It is used in the military to manufacturing rockets, missiles, satellites, radars, bulletproof vehicles, body armor, and other important military products.

In order to let you know more about we Jota company, a professional CFRP CFRTP prepreg slitter manufacturer, please watch the following video for reference.

We Jota could also supply following related machines, if you are also interested in any type, please feel free to send us an inquiry:

1. Fully Automatic Toilet Paper Maker
2. Automatic Facial Tissue Making Machine
3. Fully Automatic Thermal Paper Roll Slitting Packing Machine
4. Plastic Film, Fabric, Aluminum Foil Slitting Rewinding Machine
5. Paper Sheeter
6. Paper Tube Making Machine
7. CFRP CFRTP FRP Prepreg Slitter
8. Paper Drinking Straws Machine
9. Label Die Cutting Machine
10. Flexo Printing Machine
11. Cardboard Tube Cutting Machine