Carbon fiber composite material hand lay-up molding defects and solutions

Carbon fiber composite material hand lay-up molding defects and solutions

There are many carbon fiber molding processes, and hand lay-up is a more traditional and flexible molding process. Compared with other molding methods, the hand lay-up process is more convenient and easy to master, but there are also defects in the production process. This article will give you an analysis of common defect types and solutions.

1. Bubbles and voids

Hand lay-up mainly uses carbon fiber tows to infiltrate the resin matrix. In the process of brushing, laying, and curing, it cannot completely eliminate bubbles or regenerate new bubbles, and it cannot guarantee that the resin can fill every vacancy. Then, these defective parts become weak points of the whole part after curing and forming, which leads to partial stress concentration and damage of the part during load-bearing.

Solution: You can roll it during the laying process. At the same time, you should also pay attention to letting it stand for a while after the glue is finished, so that the bubbles in the resin glue due to stirring can be discharged.

2. Peeling between layers

When laying carbon fiber cloth in multiple layers, the carbon fiber cloth will be contaminated with less water and oil, which will cause partial delamination. Or the glue preparation time has been long, and the glue has started to heat up during the laying process, resulting in a difference in the degree of resin agglomeration between the carbon fiber layers, leading to delamination.

Solution: Do dust-proof and dust-removal treatments on the carbon fiber cloth to keep the laying environment hygienic. Speed up the pace of work during the laying process to avoid excessive heat caused by the resin glue.

3. Resin accumulation

Insufficient technical personnel or too slow speed during the layup operation will cause uneven resin impregnation and local colloidal aggregation. It is also possible that the glue flow defects due to external forces during the layup process or the offset of the carbon fiber tow during the glue brushing and pressing roller process, resulting in the uneven distribution of fibers and glue during glue sizing, forming a phenomenon of resin accumulation.

Solution: Choose experienced operators, lay the carbon fiber cloth precisely, and evenly impregnate the resin between the carbon fiber cloth layers. In the process of brushing the glue, try to keep the carbon fiber tow as stable as possible, and control the glue evenly and appropriately.

4. Insufficient curing

For large batches or large-scale carbon fiber products, due to the influence of size, thickness, and curing parameters, it is very easy to cause insufficient curing of certain parts of the carbon fiber products, which will affect the mechanical properties.

Solution: Control the ratio of resin to curing agent, add appropriate amount of fillers and pigments according to requirements, keep the raw materials carefully, do not use raw materials that have been left for a long time, and try to maintain a constant temperature of 10-15°C during operation.