Views: 0 Author: Site Editor Publish Time: 2025-06-27 Origin: Site
After molten plastic fills the mold cavity and cools, it often adheres tightly to the core or cavity. Ejector pins serve three main purposes:
✅ Automate part ejection – Eliminates manual removal, speeding up production.
✅ Prevent part deformation – Ensures even force distribution during ejection.
✅ Handle complex geometries – Works well for deep ribs, thin walls, and undercuts.
Different plastic parts require different ejector pin designs:
| Type | Description | Best For |
|---|---|---|
| Standard Ejector Pin | Cylindrical, hardened steel (e.g., SKD61), common diameters (Φ2.0, Φ3.0, Φ5.0) | General-purpose plastic parts |
| Blade Ejector (Flat Pin) | Flat surface reduces stress on thin-walled parts | Mobile cases, delicate components |
| Sleeve Ejector (Core Pin) | Inner pin + outer sleeve for deep bosses or pillars | Screw holes, deep ribs |
| Custom-Shaped Pins | Non-round shapes (square, stepped) for unique part geometries | Complex undercuts, snap-fits |
| Air Ejector Pins | Uses compressed air to assist ejection for high-precision parts | Medical devices, optics |
❌ Causes:
Tight clearance between pin and mold (ideal gap: 0.01–0.02mm)
Thermal expansion due to high mold temps
Lack of lubrication or wear
✅ Solutions:
Polish or ream the pin hole for smoother movement
Use high-temp lubricants (e.g., graphite-based grease)
Upgrade to coated pins (e.g., titanium nitride)
❌ Causes:
Small pin diameter causing high localized pressure
Premature ejection (part not fully cooled)
✅ Solutions:
Increase pin diameter or switch to blade ejectors
Adjust ejection timing and speed
❌ Causes:
Poor-quality steel (low toughness)
Misalignment or excessive ejection force
✅ Solutions:
Use high-grade steel (e.g., ASSAB 8407)
Check ejector plate alignment
Part Geometry:
Deep ribs? → Sleeve ejectors
Thin walls? → Blade ejectors
Plastic Material:
ABS/PP → Standard pins
Glass-filled nylon → Hardened or coated pins
Mold Life Expectancy:
High-volume production → Titanium-coated pins for wear resistance
Ejector pins may seem like minor components, but they significantly impact mold performance and part quality. By choosing the right type, optimizing ejection settings, and performing regular maintenance, manufacturers can prevent defects and maximize productivity.
