Causes of Cavity in Injection Mold Processing
In the process of customized injection moulding, because of the poor exhaust condition of injection moulds, water vapor, voids, volatile gases of volatile substances and data decomposition gases in the melt, air bubbles may be stored in the product interior between the melt and the surface wall of the cavity to form air cavitation, which causes concavity on the surface of the product.
Sometimes, in the thick-walled part, gas may also exist in the shortened pore caused by the lack of shortening compensation. The occurrence of air bubbles and bubbles may further lead to the lack of filling and retention in the cavity, or even to the increase of gas temperature caused by melt compression, resulting in plastic denaturation, discoloration or burning around air cavitation or bubbles, as for injection materials. If the raw material contains too much water, additives that decompose gases and recycle data may occur between them, thus forming a gas source
Therefore, plastic raw materials should be strictly dry, injection moulding machine should be applied with exhaust function, reduce the use of residual or recycling materials instead of simple decomposition additives. There is a lack of empty fillers in the products processed by injection moulding. When the data changes from melting state to condensation state, the density changes. The surface of the moulded products loses heat quickly through the die wall, and the polymer hardens.
As a result, the polymer is pulled out, causing all shortening to accumulate in a part of the product, leaving holes in the product. In a molded product with a thickness greater than 6 mm, it is difficult to avoid empty space. Air is trapped in a molten polymer, leaving bubbles in the product.