JIS Standard SKH51 Steel Precision Stepped Ejector Sleeves

Guided ejection systems rely on straight ejector sleeves to keep the ejector motion stable under load. This tapered, single-sleeve stepped design is well-suited for precision mold assemblies where alignment directly impacts part surface quality and cycle reliability.

In automotive connector and housing molds, the controlled inner-bore tolerance supports consistent guidance during repeated ejection strokes, helping reduce side-loading and sticking as molded plastic cools.

For consumer electronics and small mechanical components, this variant’s tight inner diameter control and stepped profile help maintain concentric movement for thin-wall or tight-tolerance geometries.

For medical device housings and other precision parts, the JIS-based sleeve approach is used to improve seating and positioning, supporting repeatable ejection with reduced wobble.

• Tapered single-sleeve geometry improves seating and alignment during ejection
• Tight inner-bore tolerance (+0.005/0) supports controlled fit with mating ejector elements

This ejector sleeve is manufactured from JIS Standard SKH51 precision steel, selected for its balance of wear resistance and toughness in guided motion components.

In tooling usage, SKH51 is typically supplied for precision applications in a hardened condition that supports stable geometry under cyclic contact. Final performance is achieved through appropriate quench-and-temper and finishing processes to lock in hardness while maintaining toughness against shock loads.

• Wear resistance: improved due to the high-hardness SKH51 tool-steel character, supporting long service life during repeated ejection
• Toughness trade-off: higher hardness improves wear but can reduce tolerance to impact if over-thermal treated

Comparison: compared with softer construction steels, SKH51 provides superior abrasion resistance for inner-bore guidance. Compared with higher-alloy wear grades, it still prioritizes precision stability for ejector sleeve fit and motion control.

Select dimensions to match both the ejector shaft that passes through the sleeve and the guided hole interface where the sleeve seats in the mold base.

• D/P (shaft diameter) must match the mating ejector element within the available range: 3, 4, 5, 6, 7, 8 mm.
• V (hole diameter) defines the inner bore size depending on configuration (1 ~ 1.5, 1 ~ 2, 1 ~ 3, 1 ~ 4, 1 ~ 5, 1 ~ 6 mm).
• P (tip diameter) is chosen to suit the stepped geometry: 2.5 ~ 3, 3 ~ 4, 3.5 ~ 5, 4.5 ~ 6, 5.5 ~ 7, 6.5 ~ 8 mm.

Choose L (100 ~ 150 mm or 100 ~ 200 mm) for required engagement length, and N (50 ~ 120 mm or 50 ~ 170 mm) for overall layout constraints. S (2 ~ 4, 2 ~ 6, 2 ~ 9, 2 ~ 12, 2 ~ 15, 2 ~ 18 mm) should match the available V-hole length.

Because the inner-bore control is specified as +0.005/0, maintain a controlled fit with the mating ejector component to ensure consistent guidance and minimize side-loading.