JIS Standard SKH51 Steel Precision Stepped Ejector Sleeves

This precision stepped ejector sleeve is used inside injection mold tool sets to drive and stabilize ejection forces on small, thin-walled components. Its stepped geometry supports controlled contact and reduces the risk of uneven pushing, which is especially valuable for automotive connector molds and other housings that require consistent terminal or insert clearing.

In electronics enclosure and sensor cover molds, the sleeve’s small tip diameter (P: 1.8–2.9 mm) and compact hole size enable reliable bearing removal performance without excessive disturbance to surrounding features. The SKH51 variant is suited for this task because it provides good wear resistance under repeated ejection cycles.

• Use when long, stable bearing removal is needed over the working length (L: 40–125 mm or 40–150 mm).
• Match to the specified mold interface configuration (E-SVKF-H type) to maintain alignment and cycle repeatability.

SKH51 steel is a high-performance Japanese tool steel commonly used for precision wear parts, offering a strong balance of abrasion resistance and service toughness for ejector components. In this sleeving application, the material is intended to resist polishing and edge wear caused by repeated sliding during ejection.

• Heat treatment state: quenched hardening steel (as supplied/treated for wear-resistant sleeve performance).
• Hardness: typically specified for hardened tool steel sleeves; exact HRC depends on the supplier’s final condition and is controlled to maintain dimensional stability.

Trade-offs: higher hardness improves wear resistance for thin-wall and small-diameter bearings, but may reduce toughness if over-heat treated. Compared with lower-alloy steels, SKH51 generally provides better wear resistance for long ejection running, while demanding consistent heat treatment control to avoid dimensional drift.

Select the stepped ejector sleeve dimensions by matching the ejection interface to your mold’s core/cavity layout and guidance requirements. Start with the shaft diameter (D: 2.6–6 mm) to fit the mating bore or guide feature, then verify the tip diameter (P: 1.8–2.9 mm) for the contact region that clears the molded part.

• Confirm the hole diameter (V: 0.8–1.6 mm) and V-hole diameter length (S: 1–21 / 1–26 / 1–30 mm) so the sleeve geometry aligns with the ejector pin or retaining feature path.
• Choose the correct L (40–125 mm or 40–150 mm) to cover the full working stroke and to maintain stable bearing removal across the expected ejection travel.
• Use N (20–115 mm or 20–140 mm) as the stepped reference length to ensure the transition and shoulder locate correctly within the mold stack.

Where close fit is required, rely on the sleeve’s precision fit to maintain alignment; always validate clearance with your mold assembly drawings to account for thermal expansion and manufacturing tolerances.