How to Avoid Ejector Pin Marks in Injection Molded Parts

Plastic molding in China offers a consistent and high-precision method for creating identical plastic parts through custom molds made of aluminum or steel. However, one challenge you may encounter is the appearance of ejector pin marks on your parts. These marks, also known as pin pushes, can not only affect the aesthetic quality but can also undermine the durability and performance of the product.

Why do these marks occur?

Ejector pin marks are often the result of various factors, such as:

• Excessive injection pressure, elevated mold temperature, or too quick dwell times which increase internal stress in the molded products
• Misuse or inadequate use of mold-release agents, too small of a draft, or high rejection resistance
• Inadequate design of the ejector unit, leading to rapid ejection speeds
• Poor product design resulting in a subpar structural quality

Engaging an experienced injection molding expert in China can help you minimize these challenges. They can offer design improvement suggestions and employ high-quality materials and machinery. A high-quality plastic molding process in China can significantly reduce the occurrence of ejector pin marks.

Strategies for minimizing ejector pin marks

To mitigate the presence of ejector pin marks, consider the following approaches:

• Reduce both the injection pressure and dwell time.
• Limit the amount of melt injected into the mold.
• Optimize the design of the feed system to ensure quality mold filling while slowing down the injection rate.
• Control the mold temperature and extend the cooling time to allow uniform cooling of the entire part in the mold.
• Increase the draft angle to facilitate easier part ejection from the mold.
• Choose an ejection mold design that incorporates carefully positioned ejector pins.
• Ensure the mold cavity surface is as smooth as possible.

Your trusted partner for plastic molding in China

When you choose HLH Prototypes as your plastic molding partner in China, you can rest easy. With our expertise in injection molding, we focus on delivering high-quality, injection-molded parts that meet your specifications every time.