Every injection mold that produces a part with a deep draw, a core, or a rib depends on ejector pins. When a pin galls, bends, or breaks, the mold stops — and so does production. The good news: ejector pin selection follows a clear set of engineering specifications, and the catalog data makes the right choice repeatable.
Reading the Ejector Pin Specification
The nitrided parallel inch series tells you almost everything in the part number:
- Material: AISI H13 (1.2344) — the standard hot-work tool steel for ejector pins.
- Hardness: surface 65–75 Rc (nitrided case), core 39–43 Rc — a hard wear surface over a tough core.
- Finish: 8–10 RMS, with a 1/32" max radius — the polished surface that prevents part sticking.
- Head: annealed 30–35 Rc — soft enough to peen or machine, hard enough to resist deformation.
Diameter tolerance is held at –0.0003"/–0.0008" (D dimension), and length runs +0.060"/–0.000" (L dimension) — the pin is ground to a precise length so it sits flush or slightly proud in the mold face.
How Part Numbers Are Built
In the standard system, the diameter code is followed by a length suffix. For example:
- Diameter code — identifies the pin body diameter (e.g., 3/64" is a common starting size).
- Length suffix — the overall length (e.g., 6").
- Body style — parallel body as opposed to shoulder style.
So a typical part number reads as a 3/64" × 6" nitrided parallel ejector pin. Diameters run from 1/32" up to 1", with standard lengths of 6", 10", 14", 18", 25", 36", 39", 42", 45", and 50". Some sizes are standard stock; others are made-to-order — call for price and delivery.
Choosing Nitrided vs. Through-Hardened
Pins also come in through-hard nitrided versions. The difference matters:
- Nitrided pins: hard surface over a softer, tougher core — the best all-around choice for standard ejection.
- Through-hard pins: hardened throughout for maximum column strength and wear resistance in high-pressure, high-cycle molds.
Getting It Right the First Time
Match the pin diameter to the ejector hole class in the mold plate, order the correct length so the head sits below the ejector plate face, and confirm the surface finish requirement. With those three data points, the right part number falls out of the catalog.
Related catalog items: Tooling Components stocks ejector pins (nitrided parallel, shoulder, through-hard, and metric), core pins, ejector sleeves, return pins, and ejector blades.
Call us at 814-438-7657 with your diameter, length, and quantity — we will confirm stock and ship.