MANUFACTURING PROCESS AND QUALITY CONTROL MEASURES FOR CARBON FIBER TUBES

(1) Overview of carbon fiber tubes

1.Define

Carbon fiber tube, also known as carbon fiber tube or carbon tube, is a kind of high-performance pipe made of carbon fiber composite material pre-immersed in styrene based polyester resin by heating curing pultrusion (or twisting). Carbon fiber tube with its unique material composition and advanced manufacturing process, has become an indispensable important material in modern industry.

2. Features

Carbon fiber tube has a series of excellent performance characteristics, including:
High tensile strength: the strength of carbon fiber is 6-12 times that of steel, and the tensile strength can reach more than 3000MPa or even higher.
Low density and light weight: the density of carbon fiber tubes is less than 1/4 of that of steel, which makes it a significant advantage in areas where weight needs to be reduced.
Strong corrosion resistance: carbon fiber composite materials have good chemical stability and can resist the erosion of a variety of corrosive media.
Small coefficient of thermal expansion: the carbon fiber tube has good dimensional stability when the temperature changes, which is conducive to maintaining the accuracy and service life of the product.
Good thermal and electrical conductivity: although carbon fiber tubes have certain electrical conductivity, in some applications, this characteristic can be effectively used.
Self-lubricating and energy-absorbing seismic: carbon fiber pipe also has good self-lubricating and energy-absorbing seismic ability, which improves its stability and reliability during use.
In addition, the carbon fiber tube also has a series of excellent properties such as high specific modulus, fatigue resistance, creep resistance, high temperature resistance, wear resistance, etc. These characteristics make the carbon fiber tube have a wide range of application prospects in many fields.

3. Application field

Because of its unique performance characteristics, carbon fiber tubes are widely used in many fields, mainly including:
Aerospace: The high strength and lightweight characteristics of carbon fiber tubes have significant advantages in the aerospace field, and can be used to manufacture structural parts of aircraft, rockets and other aerospace spacecraft.
Automotive industry: The lightweight characteristics of carbon fiber tubes help to improve the fuel economy and handling performance of automobiles, and can be used to manufacture automobile body, drive shaft and other components.
Sports equipment: The lightweight and high-strength characteristics of carbon fiber tubes make them ideal materials for the manufacture of high-end sports equipment, such as golf clubs, bicycle frames, etc.
Medical devices: The biocompatibility and corrosion resistance of carbon fiber tubes allow them to be used in the manufacture of medical devices such as medical implants and surgical instruments.
Construction field: Carbon fiber tubes can be used to strengthen building structures, manufacture Bridges and other engineering structural parts to improve their bearing capacity and durability.

4. The importance of manufacturing process:

The manufacturing process of carbon fiber tube directly determines its final performance and quality. By optimizing the process steps of spinning, prepreg, winding, sintering, spraying, etc., we can ensure that the carbon fiber tube meets the required strength and stiffness requirements, while improving its surface quality and corrosion resistance. In addition, different manufacturing processes are also suitable for different application scenarios and product needs, so choosing the right manufacturing process is crucial for the production of carbon fiber tubes.

5. Importance of quality control:

The quality control of carbon fiber tube is the key to ensure its performance stability and reliability. In the manufacturing process, it is necessary to strictly control raw materials, process parameters, product testing and other links to ensure that the carbon fiber tube meets the established quality standards. At the same time, through the use of advanced testing equipment and methods, quality problems in the manufacturing process can be discovered and corrected in time to avoid safety hazards and economic losses caused by quality problems. Therefore, strengthening the quality control of carbon fiber tube is of great significance to improve its market competitiveness and application value.

In summary, carbon fiber tube, as a high-performance material, has a wide range of application prospects in many fields. By optimizing the manufacturing process and strengthening the quality control, the performance stability and reliability of carbon fiber tubes can be further improved, and its application and development in more fields can be promoted.

(2) Manufacturing process of carbon fiber tube

From a professional point of view, the manufacturing process of carbon fiber tube mainly includes molding process, coil process, autoclave molding process and pultrusion molding process. The following are an overview of these major manufacturing processes, and the details and characteristics of each process are discussed in detail.

1. Overview of the main manufacturing process

1.1 Molding process

Overview: The molding process is to cut the carbon fiber prepreg of the prepreg resin, put it into the metal mold after layering, and cure the resin by heating and pressurizing, and finally release the carbon fiber tube.
Process: including prepreg cutting, laying-up, closing mold, heating pressure curing, stripping and other steps.

1.2 Winding process

Overview: The winding process is to soften the carbon fiber prepreg of the prepreg resin, roll it evenly onto the inner core mold, and then solidified at high temperature to finally get the carbon fiber tube.
Process: including prepreg softening, rolling, compaction, high temperature curing, stripping and other steps.

1.3 Autoclave forming process

Overview: Autoclave molding process is to prepreg resin carbon fiber prepreg blanks into the autoclave, through vacuum bag leak detection, temperature rise pressure insulation, temperature drop pressure stop and other steps, so that the resin curing and forming, and finally get carbon fiber tube.

Process: including vacuum bag leak detection, heating pressure insulation, cooling and decompression shutdown steps.

1.4 Pultrusion molding process

Overview: Pultrusion molding process is the continuous production of carbon fiber linear products, such as carbon fiber tubes, after dipping, extrusion, heating curing, fixed length cutting and other steps under the traction of external forces.

Process: including dipping, extrusion molding, heating curing, fixed length cutting and other steps.

2. Process details and characteristics

2.1 Molding process

Mold design: Mold design needs to consider the shape, size, accuracy and release of the product and other factors, the use of high-precision CNC processing equipment manufacturing.
Resin curing conditions control: the curing conditions such as temperature, pressure and time need to be strictly controlled to ensure the performance and quality of the product.
Product surface smoothness: The surface smoothness of molded products is high, which is conducive to subsequent processing and use.

2.2 Winding process

Core choice: Core material can choose duralumin or steel, duralumin core is light but low strength, suitable for small diameter carbon fiber tube; The steel core die is strong but heavy, and is suitable for large diameter carbon fiber tubes.
Layering Angle optimization: The layering Angle has an important influence on the mechanical properties of carbon fiber tubes, and it is necessary to optimize the design according to the force direction.
Autoclave curing: Autoclave curing ensures uniform curing of the resin and improves the mechanical properties and dimensional stability of the carbon fiber tube.

2.3 Autoclave forming process

Gas pressurization uniformity: The gas pressurization in the autoclave needs to maintain uniformity to ensure that there are no bubbles and defects inside the product.
Temperature control accuracy: Temperature control accuracy is critical to the resin curing reaction and needs to be controlled by high-precision temperature control equipment.
Product quality consistency: High quality consistency of autoclave molding process products, suitable for mass customized production.

2.4 Pultrusion molding process

Automatic control: Pultrusion molding process to achieve automatic control, high production efficiency, suitable for continuous production of carbon fiber linear products.
High efficiency: The production efficiency is much higher than other processes, suitable for mass production.
High fiber content: The fiber content of the product can be as high as 80%, and the product strength is high.
Product shape monotonicity: The product shape is monotonous and can only produce linear profiles, such as carbon fiber tubes. And because the direction of the fiber is single, the transverse strength is not high, and the longitudinal tensile strength is high.
In summary, there are a variety of manufacturing processes for carbon fiber tubes, and each process has its own unique details and characteristics. In actual production, it is necessary to choose the appropriate manufacturing process according to the performance requirements of the product, production efficiency and cost.

Manufacturing Process	Overview	Procedure	Details & Characteristics
Mold Pressing Process	Carbon fiber prepreg impregnated with resin is placed in a metal mold, heated, and pressurized for curing	Prepreg cutting, layering, mold closing, heating & pressurizing for curing, demolding	– Mold design considers shape, size, precision, and demolding- Strict control over resin curing conditions- High surface smoothness of the product
Rolling Process	Softened carbon fiber prepreg impregnated with resin is rolled onto an inner core mold and cured at high temperature	Prepreg softening, rolling, compacting, high-temperature curing, demolding	– Core mold selection between hard aluminum or steel based on diameter- Optimization of layering angles affects mechanical properties- Autoclave curing ensures uniform resin curing
Autoclave Molding Process	Carbon fiber prepreg is placed in an autoclave, undergoing steps such as vacuum bagging, heating, pressurizing, and curing	Vacuum bag leak check, heating & pressurizing for curing, cooling & pressure release	– Uniform gas pressurization within the autoclave- Precise temperature control is crucial for resin curing- High consistency in product quality, suitable for mass customization
Pultrusion Process	Carbon fiber or its fabric is pulled through a series of steps including impregnation, extrusion, heating for curing, and cutting to length for continuous production	Impregnation, extrusion molding, heating for curing, cutting to length	– Automated control, high production efficiency- Fiber content in the product can reach up to 80%, resulting in high strength- Product shape is limited to linear profiles, such as carbon fiber tubes- Single fiber direction results in lower transverse strength but higher longitudinal tensile strength

Choose the right carbon fiber tube for your business

(3) Quality control measures for carbon fiber tubes

As a manufacturer of NQ carbon fiber tubes, we understand the importance of quality control to ensure the performance stability and reliability of carbon fiber tubes. The following are our perspectives from raw material quality control, manufacturing process control, post-processing and testing, and special quality control methods.

1. Raw material quality control

1.1 Selection and inspection standard of carbon fiber prepreg

Selection criteria: We strictly screen carbon fiber prepreg suppliers to ensure that they use high-quality carbon fibers and well-matched resin substrates. Prepreg needs to pass strict factory inspection, including resin content, volatile content, fiber distribution uniformity and other indicators, all need to meet or exceed industry standards.
Inspection standard: In the NQ factory, we set up a special prepreg inspection laboratory to reinspect each batch of prepreg, including appearance inspection, mechanical property testing, chemical property analysis, etc., to ensure the stable and reliable quality of raw materials.

1.2 Inner core mold material and precision requirements

Material selection: The inner core mold material directly affects the outer diameter size and surface quality of the carbon fiber tube. According to product requirements, we choose metal materials with good rigidity and thermal stability, such as duralumin or steel, to ensure that the mold does not deform during the heating and curing process.
Accuracy requirements: The mold processing accuracy needs to reach the micron level to ensure that the outer diameter of the carbon fiber tube is accurate. At the same time, the mold surface needs to be polished to reduce the friction resistance between the prepreg and prevent wrinkles and streaks.

2. Manufacturing process control

2.1 Optimization of process parameters

Temperature control: According to the curing characteristics of the prepreg resin, we optimize the process parameters such as molding temperature, heating rate, molding temperature and holding time. By means of DSC analysis, the resin can fully react in the curing process to achieve the best curing effect.
Pressure control: During the molding and rolling process, we use a high-precision pressure control system to ensure a tight bond between the prepreg layers and eliminate bubbles and glue-rich phenomenon.

2.2 Precision of mold temperature and pressure control

High precision control: We are equipped with advanced mold temperature control system and pressure sensor, real-time monitoring and adjustment of mold temperature and pressure, to ensure that the process parameters are stable and controllable.

2.3 Prepreg lay-up and compaction technology

Prevent wrinkles and streaks: During the layup process, we use advanced layup equipment and technology to ensure that the prepreg is flat and wrinkle-free. The mechanical properties of carbon fiber tube can be improved by rational design of layup Angle and sequence.
Compaction technology: After the layup is completed, we use pre-compaction technology to apply a certain pressure to compress each layer of fiber to prevent fiber relaxation and glue-rich phenomenon.

3. Post-processing and testing

3.1 Surface Treatment

Grinding, polishing, painting: We perform a multi-process surface treatment of carbon fiber tubes, including preliminary grinding to remove burrs and uneven parts, fine polishing to improve surface finish, and spray painting to protect the surface from corrosion. Process parameters and quality standards are strictly controlled at each step.

3.2 Dimensional accuracy detection

Inner diameter, outer diameter, wall thickness uniformity: We use high-precision measuring instruments to accurately measure the inner diameter, outer diameter and wall thickness of carbon fiber tubes to ensure that the dimensional accuracy meets the design requirements. At the same time, through statistical analysis and process control means, the manufacturing process is continuously optimized to improve the dimensional stability.

3.3 Mechanical performance test

Strength, stiffness, corrosion resistance: We carry out rigorous mechanical performance tests on carbon fiber tubes, including tensile strength, bending stiffness, corrosion resistance and other indicators. The mechanical properties and service life of the product are evaluated by comparing the standard sample with the test results.

4. Special quality control methods

4.1 Combination technology of pre-compaction and temperature control

Technical features: We innovate the combination of pre-compaction and temperature control, by precisely controlling the temperature and pressure conditions during the prepreg laying process, optimize the compaction effect of the prepreg and improve the curing quality. This technology effectively solves the problems of wrinkles, streaks and rich glue which are easy to appear in the traditional process.

4.2 Heat shrink process to improve surface quality and manufacturing accuracy

Application effect: The heat shrink process is introduced in the process of high temperature curing, and the shrinkage characteristics of the heat shrink material are used to shape and strengthen the carbon fiber tube. This method not only improves the surface quality of the carbon fiber tube, but also enhances its structural stability and dimensional accuracy.

4.3 Application of automatic testing equipment

Improve inspection efficiency and accuracy: We introduce advanced automated inspection equipment for non-destructive testing and online monitoring of carbon fiber tubes. These devices provide real-time feedback on quality information during the production process and automatically adjust process parameters to correct deviations. Through the application of automated testing equipment, we have significantly improved the testing efficiency and accuracy and reduced the impact of human error on product quality.

In summary, NQ carbon fiber tube manufacturers have taken a series of professional and effective measures in the quality control of carbon fiber tubes, from raw material quality control to manufacturing process control to post-processing and testing and special quality control methods, each link is strictly checked to ensure that the performance of carbon fiber tubes is stable and reliable to meet the needs of customers for high-quality products.

(4) The future development trend of carbon fiber tube manufacturing process and quality control

The future development trend of carbon fiber tube manufacturing process and quality control will closely revolve around the application of new materials and new technologies, the automation and intelligent development of manufacturing process, and the standardization and internationalization trend of quality control.

1. Application prospect of new materials and new technologies

Development of high-performance carbon fiber materials:

With the continuous progress of material science, the mechanical properties, corrosion resistance and heat resistance of carbon fiber will be further improved. For example, by changing the ratio of raw materials and adjusting the production process, higher strength and higher modulus carbon fiber materials can be prepared.

The research of new carbon fiber composite materials will also bring more possibilities for the application of carbon fiber tubes. For example, the addition of conductive fibers or sensor elements enables carbon fiber tubes to have conductivity, sensing functions, or structural health monitoring capabilities.

Application of multi-functional composite materials:

In the future, carbon fiber tubes will no longer be limited to the application of a single material, but to the direction of multi-functional composite materials. By combining with other materials, more excellent comprehensive properties can be achieved to meet the needs of different fields.

2. Automation and intelligent development of manufacturing process

The popularity of automated production lines:

With the continuous development of automation technology, the manufacturing of carbon fiber tubes will gradually realize automated production. Automated production lines can greatly improve production efficiency, reduce production costs, and reduce the impact of human factors on product quality.

For example, the use of advanced equipment such as automatic layering equipment and automatic autoclave can achieve accurate cutting, layering and curing of carbon fiber prepreg, improving the stability and consistency of the product.

Construction of intelligent manufacturing system:

On the basis of automated production, the construction of intelligent manufacturing system will become the future development trend. Through the integration of the Internet of Things, big data, artificial intelligence and other technologies, to achieve real-time monitoring of the production process, fault warning and intelligent scheduling functions.

Intelligent manufacturing system can flexibly adjust production process parameters according to market demand and product characteristics, optimize production flow, improve production efficiency and product quality.

3. Quality control standardization and internationalization trend

Improvement of quality control standards:

With the continuous expansion of the application field of carbon fiber tube, the requirements for product quality are becoming higher and higher. In the future, the quality control standards of carbon fiber tubes will continue to improve, covering raw material inspection, manufacturing process control, finished product performance testing and other aspects.

Through the development of strict quality control standards, the quality stability and consistency of carbon fiber tubes can be ensured, and the market competitiveness of products can be improved.

International quality certification and cooperation:

With the continuous development of international trade, the international competition of carbon fiber tubes is also becoming increasingly fierce. In order to enhance the international competitiveness of products, domestic carbon fiber tube manufacturers will actively seek international quality certification and cooperation opportunities.

Through exchanges and cooperation with international leading enterprises, we can introduce advanced quality control concepts and technical means to improve the internationalization level of products.

In summary, the future development trend of carbon fiber tube manufacturing process and quality control will show the wide application of new materials, new technologies, the automation and intelligent development of manufacturing process, and the standardization and internationalization trend of quality control. These trends will together promote the continuous progress and innovative development of the carbon fiber tube industry.

(5) Conclusion

The core of the carbon fiber tube manufacturing process and quality control lies in the continuous improvement of surface quality and manufacturing accuracy, which is the key to ensuring its excellent performance and meeting the needs of high-end applications. Through fine raw material screening, strict manufacturing process control and comprehensive quality inspection system, we achieve high-precision manufacturing and excellent surface quality of carbon fiber tubes, laying a solid foundation for its wide application in aerospace, automotive, sports equipment and other fields. Looking forward to the future, with the continuous progress of technology and the continuous expansion of the market, carbon fiber tubes with their unique performance advantages will certainly show unlimited application potential in more high-end and broader markets, and promote the innovation and development of related industries.