Posts

Showing posts from December, 2018

Why venting important for injection molding

Image
In a sense, the injection mold is also a displacement device where the hot plastic melt enters into the mold cavity while displaces the air in the mold cavity. In fact, the air in the mold is not limited to the cavity, especially the three-plate injection mold, and the air existing in the flow path cannot be ignored. In addition, the plastic melt produces a small amount of decomposition gas. These gases must be discharged in time If the venting performance of the mold is poor, it is easy to produce bubbles, silver streaks, clouds spot, short shot, scorch marks and other defects Therefore, a reasonable layout of the venting structure should be provided on the mold to avoid defective products caused by poor venting. https://www.youtube.com/watch?v=DecwAPl6pvU Venting slot For the molds for making large and medium-sized plastic parts, the amount of gas to be removed is large. Generally, the Venting slot should be cut on the side of the plastic mold on the parting surface. The position of ...

2 points for PC injection molding product

Image
Transparent parts have their special characteristics and functionality. The poly-carbonate injection molding will inevitably be used for auto part. When injection molding, we often encounter some thick-walled transparent  injection molded parts. For performance reasons, these plastic parts are made of PC . When the average wall thickness exceeds 6mm and the MAX wall thickness is more than 12mm, the plastic parts often have two problems during injection molding: one is that the surface shrinks, and the other is the air bubbles inside the product. As to the thicker wall thickness, deformation is not the main problem. Injection molding of transparent PC plastic parts has the most problems: Shrinkage The main reason is that the wall thickness is too thick to lead to product shrinks. In this  process, more melt must be injected to prevent shrinkage, and a higher mold temperature is required to shrink the product as a whole (opaque products require to reduce the mold temperature...