The Ejector Pin Is the Workhorse of Mold Ejection
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 DMS EP-Series Specification
Tooling Components distributes the full DMS Components ejector pin range. The nitrided parallel inch series (catalog prefix EP) 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.
Catalog Numbers: What EP04L06P Means
In the DMS system, the diameter code is followed by a length suffix. For example:
- EP04 — 3/64" diameter pin.
- L06 — 6" overall length.
- P — parallel body (as opposed to shoulder style).
So EP04L06P is a 3/64" × 6" nitrided parallel ejector pin. Diameters run from 1/32" (EP03) to 1" (EP100), with standard lengths of 6", 10", 14", 18", 25", 36", 39", 42", 45", and 50". Sizes marked in blue in the catalog are available but generally not stocked — call for price and delivery.
Choosing Nitrided vs. Through-Hardened
DMS also lists through-hard nitrided pins (catalog section B3/B4). 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 item: Tooling Components stocks DMS ejector pins (nitrided parallel, shoulder, through-hard, and metric), core pins, ejector sleeves, return pins, and ejector blades — plus the full DMS mold component range of 12,000+ items.
Call us at (800) 992-4766 with your diameter, length, and quantity — we will confirm stock and ship.