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2026
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Introduction to Mold Secondary Ejection Components
Author:
timould
Secondary ejection components are core parts for phased ejection in injection molding and die-casting molds. They solve problems like product scratching, mold sticking and deformation in one-time ejection, especially for products with deep cavities, undercuts or thin walls. Their core principle is to achieve two-step ejection ("slow first then fast, local first then overall") through limiters, levers, elastic parts and sliders.
These components split ejection into two steps: the first step releases undercuts, relieves stress or separates runners, and the second fully ejects the product. They are widely used in molds for deep-cavity parts, undercut products, thin-walled parts and those needing ultra-long ejection strokes.
Common types include limit components (limit pins, bolts), lever/swing block components (most commonly used), elastic components (springs, elastic ejector pins), slider/wedge components (for complex undercuts), ejector/push plate components (double-layer ejector plates) and special standard parts (secondary ejection hooks).
Practically, they are often used in combinations (e.g., swing block + limit pin + spring). When selecting, consider product structure, ejection stroke, mold space, cost and maintenance for optimal use.
mold
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