With the application of plastic products in the automotive industry, automotive plastic molds have also developed rapidly. As for the materials used in automotive plastic molds, most of them are engineering grade plastics. So, what are the engineering grade plastics commonly used in automotive plastic molds?
1. Glass fiber reinforced plastic
Glass fiber reinforced plastic is based on the original pure plastic, adding glass fiber and other additives to increase the use range of the material. Generally, most of the glass fiber reinforced materials are used in automobile structural parts, such as PP, ABS, PA66, PA6, PC, POM and so on.
(1) Advantages of glass fiber reinforced plastic:
① After glass fiber is reinforced, it is extremely high temperature resistant material, which is much better than before without glass fiber, especially nylon plastic raw materials;
② It restricts the mutual movement of the polymer chains of the plastic, resulting in a decrease in shrinkage and a greatly improved product rigidity;
③ Glass fiber reinforced plastic will not crack due to stress, thus improving the impact resistance;
④ Glass fiber is a high-strength material, which improves the strength of plastic;
⑤ Due to the addition of glass fiber and other additives, the combustion performance of reinforced plastics is greatly reduced.
(2) Disadvantages of Glass Fiber Reinforced Plastic:
① It will change the opacity of plastic materials;
② The toughness of plastic is reduced, which increases the brittleness of the product;
③ The viscosity increases, the fluidity becomes worse, and the injection pressure must increase;
④ Its fluidity is poor. In order to be able to inject normally, the injection temperature of all reinforced plastics should be increased by 10℃ to 30℃ than before without glass fiber;
⑤ The moisture absorption performance of reinforced plastic is strengthened, so it must be dried during injection molding;
⑥ In the plastic injection molding process, the glass fiber can enter the surface of the plastic product, which makes the surface of the product very rough;
⑦ Glass fiber is a material with high hardness. After the additives are volatilized at high temperature, it is a very corrosive gas, which greatly wears and corrodes the screw of the injection molding machine and the plastic mold of the automobile. Therefore, when producing automotive plastic molds and injection molding machines that use these materials, attention should be paid to the surface anti-corrosion treatment and surface hardness treatment of the equipment.