Why ejector pin selection matters
Ejector pins push the molded part off the core after each shot. They take the full ejection load, run in close-fitting bores, and see every cycle the mold runs. A pin that is undersized, the wrong material, or poorly finished shows up fast as galling, bent pins, or a part that sticks in the cavity.
Ejector pin types
- Straight pins: The workhorse. A constant-diameter body with a head that seats in the ejector plate. Used for most flat and shallow features.
- Shoulder (step) pins: A reduced-diameter body with a larger shoulder. Used where the pin must reach deep into the mold but the bore must stay small, or where the pin needs a positive stop.
- Blade pins: A flat, rectangular cross-section for ejecting thin ribs and walls where a round pin would not fit.
- Core pins: Form internal features and bores; often run hotter and need higher-grade materials.
Materials and finishes
- H13: Hot-work tool steel, the standard for ejector pins that see heat and wear. Nitrided for a hard, wear-resistant surface.
- M-2: High-speed steel with excellent wear resistance and toughness; a common choice for core pins and high-cycle tools.
- Stainless: For medical, cleanroom, and corrosive molding where rust and contamination are concerns.
- Black nitride / armor coatings: Add surface hardness and lubricity for greaseless or high-wear applications.
How to read the part number
Ejector pin part numbers encode the body diameter and overall length. For example, a PCS designation like EP-50-20 identifies the pin diameter and length; Progressive Components uses its own catalog prefix for the same nominal sizes. The number tells you the pin size, but the head diameter, head thickness, and shoulder length are set by the standard — so match the full designation, not just the body size.
Common failure modes
- Galling: Pin and bore surfaces weld under load — check material, finish, and clearance.
- Bent pins: Undersized diameter or misaligned ejector plate — verify load and alignment.
- Sticking part: Pin too short or wrong draft — confirm pin length and part geometry.
Catalog item plug: Tooling Components sells ejector pins from PCS and Progressive Components in straight, shoulder, and blade styles across H13, M-2, and stainless — sized by diameter and length for your ejector plate. Call (814) 438-7657 or email sales@toolingcomponent.com for same-day pricing.