How to Eliminate Ejector Pin Marks in Injection Molding?

Avoid excessive injection of melt.

Reduce injection pressure and dwell pressure. Shorten dwell time.

Reduce injection rate, optimize the design of the feed system and realize a sound mold filling.

Properly improve mold temperature, prolong cooling time and reduce cooling speed. Optimize temperature control and product structure to encourage uniform cooling of products in the mold.

Increase draft while ensuring proper retaining mode of plastic parts in the mold.

Analyze the ejection resistance and distribution, then use a suitable ejection mold with properly arranged ejector pins, trying to achieve a balanced ejection. If you see large ejection resistance, increase the number of ejector pins in those areas and expand the section dimensions of the ejector pin. Increase wall thickness where the ejector mark can easily occur in an effort to strengthen the products’ resistance to stress.

Increase smoothness for the cavity surface. Polish along the ejection direction of plastic parts in the final stage of polishing. If you’re polishing a mold that already has ejector pin marks, apply polish corresponding to the ejector mark.

Properly spray the mold-release agent.