Configuration Matters as Much as Material
Two ejector pins can be the same diameter, same material, same hardness — and behave completely differently in the mold. The difference is the configuration: parallel body vs. shoulder body.
Parallel Pins: Simple and Flexible
A parallel ejector pin has a constant body diameter below the head. It is the most common configuration, easy to stock, and simple to install. Its limitation: depth control depends on the head seating consistently in the ejector plate pocket, and the pin can float slightly under load.
Parallel pins are ideal for:
- Standard ejection where depth tolerance is not critical.
- Applications where the pin is ground to a specific length in-house.
- Economical general-purpose molds.
Shoulder Pins: Positive Depth Location
A shoulder ejector pin has a reduced body diameter behind a shoulder, with the shoulder locating positively in the ejector plate. The shoulder prevents the pin from pushing through under pressure, holding the ejection depth repeatably, cycle after cycle.
Shoulder pins are the right call for:
- Deep-draw parts where ejection depth must be exact.
- High-cavity-pressure molds where float would cause flash or drag.
- Automated molding where dimensional consistency is audited.
DMS lists nitrided and through-hard shoulder pins in inch and metric, with the same EP-style diameter codes and length suffixes.
Oversize Sleeves: The Repair That Skips the Machine Shop
After years of cycles, ejector holes wear oversize — the pin wobbles, drags, and starts marking parts. The traditional fix is to weld and re-bore the plate, or make a stepped pin. The faster fix: oversize ejector sleeves.
DMS stocks oversize ejector sleeves with the OD sized to the worn hole and the ID sized to the original pin. You ream the hole to the oversize sleeve OD, press in the sleeve, and continue with the original pin diameter. No re-boring of the plate to a new pin size, no custom grinding, no mold re-qualification.
When to Use Which
- Depth critical? → shoulder pin.
- Hole worn oversize? → oversize sleeve, keep the original pin size.
- General duty, in-house adjustment? → parallel pin.
Related catalog item: Tooling Components stocks DMS shoulder ejector pins (nitrided and through-hard, inch and metric), parallel pins, and oversize ejector sleeves. Core pin retainers and knockout rod extensions are also available for repair and rebuild work.
Contact us at (800) 992-4766 — we will match the configuration to your mold and get it shipped.