Two Small Components That Prevent Big Failures
Most ejection problems are diagnosed as "the ejector system is binding" or "the ribs are sticking." Both symptoms trace back to components that are easy to overlook: return pins and ejector blades.
Return Pins: The Alignment Guardians
Return pins (also called pull-back pins or push-back pins) mount in the ejector plate and ride in bushings in the mold base. Their job is to keep the ejector assembly square as it travels — and to return it to the retracted position before the mold closes.
DMS return pins are nitrided, giving them a hard wear surface for the thousands of cycles they run against the bushing. When a return pin wears or binds:
- The ejector plate cocks, loading every ejector pin unevenly.
- Pins bend or break at the head.
- Mold halves close on a partially returned ejector — a crash event.
Inspect return pins and their bushings for wear on a regular PM schedule; replace them as a set with matched lengths.
Ejector Blades: Ejecting What Round Pins Cannot
Thin ribs, narrow slots, and fragile mold features need a flat, wide contact surface — not a round point. That is the ejector blade's job. DMS lists through-hard ejector blades in metric sizes, designed to reach into slots that would break a round pin of the same width.
Blades are ground to a precise width and thickness, with a shoulder for positive location in the ejector plate. Because they are through-hardened, they resist the bending loads that thin-section ejection imposes.
Selection Checklist
- Return pins: match diameter to the bushing bore, length to the ejector stroke, and nitrided surface for wear life.
- Ejector blades: width and thickness must match the slot; shoulder style locates positively; through-hard for bending resistance.
- Clearance: verify blade-to-core clearance so the blade does not drag during ejection.
Stock Means Uptime
When a return pin binds or a blade snaps, the mold is down. Standard DMS return pins and ejector blades are stocked items at Tooling Components — same-day shipping from Erie, PA, with hot-shot delivery within 100 miles when the line is stopped.
Related catalog item: Tooling Components stocks DMS return pins (nitrided, inch), ejector blades (through-hard, metric), and the associated bushings and retainers. Section A (pins & bushings) and Section B (mold components) of the DMS catalog cover the full range.
Call us at (800) 992-4766 with your pin diameter, stroke, and blade dimensions.