Manufacturing Carbon Fiber Products: Quality Control Points and Mitigation

The manufacturing process of carbon fiber is complex and challenging. Process variables such as time, temperature, gas flow, and chemical composition need to be closely monitored during each stage of the production.

In this post, we will inform you how to control the whole manufacturing process from following three aspects:

  • Key points of manufacturing raw material 
  • How to make good carbon fiber parts, and
  • What problems can occur and how to fix them.

After looking through the passage, you are able to monitor the whole manufacturing process and know what kinds of details should be focused on in order to make the best carbon fiber products with high efficiency.

1. How to manufacture good raw material?

To manufacture good products, all the manufacturers should choose good raw materials at first and then focus on the latest technology. The paragraphs below will give you some advice.

1.1 Use high quality PAN

High quality PAN is the primary prerequisite for the manufacture of high performance carbon fiber.

Precursor fiber with high purification, high strength, good densification and smooth surface are the primary material for producing high performance carbon fiber.

Carbon fiber manufacturing needs to start from the polymerization monomer of precursor fiber, whose quality determines both the properties of the carbon fiber and the production cost.

1. 2 Minimize impurity content

Minimizing impurity content is a fundamental measure to improve the tensile strength of carbon fiber, which is also a hot topic for researchers. In a sense, the process of increasing strength is essentially a process of reducing impurity content.

1.3 Shorten pre-oxidation time

In the pre-oxidation process, under the premise of ensuring homogenization, the pre-oxidation time should be shortened as much as possible, which is a directional problem of reducing production costs.

1.4 High temperature technology and equipment

The carbonization temperature is generally between 1,300 and 1,800°C, and the graphitization temperature is generally between 2,500 and 3,000°C.

When the equipment is supposed to continuously operate at such high temperature, it is particularly important to focus on the latest high-temperature technology, such as microwave technology, plasma technology and induction heating technology under inert gas protection and anaerobic conditions.

2. How to make carbon fiber parts?

When it comes to making carbon fiber parts or products, manufacturers usually lay out carbon fibers in different directions and in different layers to form a part shape.

Then the carbon fiber is solidified under a certain pressure and temperature. There are generally 4 different methods as follows:

2.1 Paste molding

Paste molding is a traditional backward manual processing method.

The dipping is manually applied to the mold and then cured. The advantage is that the process can manufacture complex parts easily, and it is suitable for small batch manufacturing.

But the disadvantage lies in low production efficiency, high labor intensity and poor dimensional accuracy.

2.2 HP-RTM

In this process, the carbon fiber material is put into a closed mold. Then inject resin into the mold to form a solid under vacuum and pressure. This process is called high-pressure injection, which is quite uncomplicated and can save additional equipment costs with computer control.

Source Image: HP-RTM

High-pressure injection with high temperature molding can be used to prepare integral structural parts with large size, complex structure and smooth surface.

Using HP-RTM process, the consumption of raw materials is quite low, and product quality is stable, which is suitable for large-scale production.

In addition, the injection of resin can greatly reduce the toxicity of volatile gas to human bodies and environment during the curing process of the resin.

2.3 Wet Molding

Wet molding is an economical alternative to the HP-RTM process with simpler process and shorter cycle times, which can be used to produce CFRP parts possessing low three-complexity and large surface area such as roofs, doors, hoods, bumpers Suitcase, etc.

Its advantages are obvious: resin is quickly coated in an open environment without forced flow of the resin in the mold, leading to the reduction of bubbles.

Also, the coating process of resin and the curing process of the components can be carried out simultaneously. As a result, the production cycle can be shortened to less than 180 seconds.

3. What problems can occur and how to fix them?

Although you have concerned all the key steps we mentioned before, sometimes some small issues will still occur. So we need to know what problems can happen, so that we can handle them better with solutions.

When you find resin accumulation and partial lack of material, you should know it may be caused by wrong uniformity for subsidiary materials or wrong ratio for epoxy.

Sometimes, the product design and molds design are really bad, and you need to optimize the products or molds.

The causes of problems are different, so remember to deal with them according to specific situations.

That is all about the quality control issues of carbon fiber, and we hope it is useful. Don’t hesitate to leave you comment below if you have any questions.

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