Ejector Leader Pins for Medium-Large Mold
Precision guide pins ensuring ejector plate alignment in medium to large injection molds. Two variants: both-ends-stepped for dual-plate registration and bolt-fixing counterbore for positive thermal retention.
Products in This Category
Both Ends Stepped Ejector Leader Pin
Stepped shoulders engage support plate and retainer plate. Max rigidity for large ejector assemblies.
Bolt Fixing Counterbore Ejector Leader Pin
Bolt-through-head retention. Positive locking against thermal pullout in heated molds.
Variant Selection: Stepped vs Counterbore
Two retention methods address different failure modes in ejector plate guidance. Match to your mold's primary risk:
| Factor | Both Ends Stepped | Bolt Fixing Counterbore |
|---|---|---|
| Alignment Rigidity | Maximum (dual registration) | Good (single registration) |
| Thermal Retention | Medium (interference fit) | Maximum (bolt locking) |
| Installation | Press-fit both ends | Press-fit shaft + bolt head |
| Maintenance | Requires press to remove | Bolt removal for easy service |
| Best For | Large ejector assemblies needing precision | Hot molds with thermal pullout risk |
Decision rule: If your mold temperature stays below 80°C and alignment precision is critical, use both-ends-stepped. If the mold runs hot (>80°C) or you've experienced pin loosening due to thermal cycling, switch to counterbore for positive bolt retention. For detailed design examples and installation diagrams, see our Stepped vs Counterbore Ejector Leader Pins — When to Use Each.
Pairing Requirements
Installed in ejector retainer plate
Installed in support plate
Installation note: Pin-to-bushing clearance should be 0.005–0.015 mm for standard molds and 0.003–0.008 mm for precision molds. For a step-by-step installation procedure in multi-plate molds, see our How to Align Ejector Plates in Multi-Plate Molds — Leader Pin Installation.
Application
Large Mold Ejector Alignment
Molds >500mm require guided ejection to prevent plate tilt, uneven ejection, and mold damage.
Without guided ejection, large ejector plates deflect under their own weight plus ejection force, causing uneven part release and progressive wear on ejector pin bores.
Recommended: 4 corner pins + 2 mid-span pins for molds over 800mm
Hot Mold Ejector Guidance
Molds running at elevated temperatures (>80°C) cause thermal expansion that can loosen press-fit components over time.
Bolt-fixing counterbore pins provide positive mechanical retention independent of thermal expansion, preventing pin migration during heating/cooling cycles.
Recommended: Bolt Fixing Counterbore variant
Decision rule: Ejector leader pins are essential in any mold where the ejector plate travels >80 mm or weighs >50 kg. For detailed guidance, see our Stepped vs Counterbore Ejector Leader Pins — When to Use Each.
Frequently Asked Questions
When should I use both-ends-stepped vs counterbore ejector leader pins?+
What is the maximum pin diameter for ejector leader pins?+
How do I align the ejector plate in a 4-plate mold using leader pins?+
Engineering Resources
Need Ejector Leader Pins?
Specify mold size, ejector plate thickness, variant (stepped or counterbore), and number of pins needed. Custom diameters up to Ø80 mm available.