SKD61 Steel Stepped Ejector Sleeves & One-Step Center Pin Sets

Stepped ejector sleeves and one-step center pin sets are used in precision injection mold ejection systems where repeatable alignment is critical. In automotive connector and small housing molds, the stepped sleeve guides the center pin to reduce lateral play during ejection. The nitrided SKD61 variant helps maintain stable wear performance under high cycle counts, supporting consistent ejection accuracy.

• Medical device housings: uses tight inner diameter fit (e.g., H7) to stabilize alignment and support fine tolerances in pin-assisted ejection.
• Consumer electronics enclosures: the concentricity target (0.06 mm) improves concentric guidance for reliable part release of flat or thin-wall components.

For each scenario, the stepped geometry improves concentric guidance of the center pin set, while the nitrided surface improves resistance to sliding wear and helps preserve function over repeated ejection cycles.

This product uses SKD61 tool steel for stepped ejector sleeves and center pins. SKD61 corresponds to the widely used H13 (AISI/ASTM H13) class of hot-work tool steels, offering a balance of strength and wear resistance for mold tooling applications.

• Heat treatment state: nitrided surface treatment is specified to improve near-surface hardness and wear resistance while the steel core retains toughness.
• Wear resistance vs. toughness: nitriding increases surface durability for sliding contact during ejection, while the tempered steel core supports resistance to cracking under cyclic loading.
• Hardness (HRC): hardness values are not provided in the supplied specification data; final HRC should be confirmed for the exact size/heat lot when qualifying for your press conditions.

If an alternative is considered, the key trade-off is typically surface hardness and scuff resistance (improved by nitriding) versus bulk toughness and machinability (dependent on quench & temper practice).

Select the center pin and stepped sleeve dimensions by matching the shaft and tip geometry to your ejector layout and cavity/core features. Start with D (shaft diameter) in the range 5 ~ 12 mm, and choose the corresponding P (tip diameter) from 3.5 ~ 7.5 mm. For the mating bore, use V (hole diameter) of 2 ~ 4 mm and the center pin tip shape code (A, B, C, D, E, S), ensuring the tip profile matches the recess geometry.

• For the center pin tip, confirm A (1 ~ 2 mm) or E (1 ~ 2 mm) as specified for your selected tip shape.
• Match recess diameter C, noting multiple ranges (e.g., 0.1 ~ 1, 0.3 ~ 1, 0.1 ~ 1.5, 0.2 ~ 1).
• Verify overall lengths: F (shaft diameter length) ranges 50 ~ 349.5 or 100 ~ 399.5 depending on configuration; L is 50 ~ 250 or 80 ~ 300 mm, and X (full length) ranges up to 70 ~ 400 mm (configuration dependent).

Assembly fit references include an H7 inner diameter tolerance for the sleeve; maintain the intended clearance/interference for stable guidance. If choosing head thickness, use 6 mm (JIS), 8 mm (JIS), or 4 mm (T4) as applicable. Dimension R (0.3 ~ 5 mm) should be checked for feature radius compatibility; it is fixed by the selected size.