Ejector Pin Selection Guide for Plastic Molds: 3 Key Details to Avoid 80% of Production Failures
Release time:
2026-05-12 14:55
For plastic mold manufacturers, ejector pins are among the most basic yet critical components. Many seemingly tricky injection molding problems—such as ejection marks, product cracking, poor demolding, mold jamming, or even broken pins—often stem from improper ejector pin selection. Today, we’ll break down three key details to help you effectively reduce production failures.
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Material and Hardness: Match to Product and Mold Conditions The material of the ejector pin directly determines its wear resistance and impact toughness. Different plastic materials require corresponding pin materials: for general plastic parts, SKD61 ejector pins work well; for engineering plastics with high glass fiber content, we recommend HSS high-speed steel or DLC-coated pins to enhance wear resistance and extend service life. Hardness alone isn’t everything—balance with toughness is essential to avoid pin breakage under impact loads.
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Dimensions and Tolerances: Precision Determines Demolding Performance The ejector pin’s diameter, length tolerance, and fit clearance with the pin hole directly affect demolding results. Too small a clearance can cause pin jamming, while too large a gap leads to flash or material leakage. Especially in precision molds, the coaxiality and straightness errors of ejector pins must be strictly controlled to prevent uneven ejection force, which causes product deformation or ejection marks.
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Structure and Surface Treatment: Adapt to Complex Product Requirements For deep-cavity, thin-walled, or high-appearance-requirement products, standard straight ejector pins may not suffice. Consider special structures like stepped pins, flat ejector pins, or ejector sleeves. Additionally, ejector pin surface polishing and coating processes (e.g., nitriding, DLC coating) improve demolding smoothness, reduce sticking risks, and enhance surface quality.
Proper ejector pin selection not only solves most demolding issues but also significantly reduces mold maintenance costs and improves production efficiency. We Himould specialize in providing various plastic mold components, including ejector pins, guide pins, and inserts, with custom drawing support. Available materials include SKD61, HSS, and DLC-coated options, with strict precision control to fit all mold conditions. For ejector pin selection or customization inquiries, feel free to contact us anytime.
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