What is Compression Molding?
Compression molding is the operation of first putting powdered, granular, or fibrous plastic into the mold cavity at the molding temperature, and then closing the mold to press to shape and solidify it. Compression molding materials usually include thermosetting plastics, thermoplastics, and rubber materials.
The compression molding process has the following advantages:
1) Since there is no pouring system, the loss of raw materials in the compression molding process is small.
2) In plastic compression molding, since the plastic pressure in the mold cavity is relatively uniform, the flow distance generated by the pressure is relatively short, the amount of deformation is small, and the flow is multi-directional. Therefore, the internal stress of the product is very low, so the warpage of the product is also small, and the mechanical properties are relatively stable.
3) It is especially suitable for forming thin-walled products that cannot be warped and can form bigger flat makeup and pot-shaped products.
Compression molding also has the following disadvantages:
1) For complex products with recesses, side slopes or small holes, etc., molding methods and customized plastic parts may be used from time to time, because this requires the structure of the mold to be more complex, and it may also cause the mold to pin when the melt flows under higher pressure. Bending or even breaking of shafts and side cores.
2) Due to the high viscosity of the general molding compound melt, it may be problematic to fill the mold completely. To ensure that the melt can completely fill the mold, the molded material must be preformed into a blank with a special shape. This is particularly important when the mold does not provide a way to limit the molding material to a specific measure.
3) When the curing stage is over and the mold is opened and the product is taken out, the different stiffness of the product is an important issue to be considered.