JIS Standard SKH51 Steel Rectangular Ejector Pins with Engraving

Where they’re used: These rectangular ejector pins are built into injection mold ejector systems where accurate alignment and repeatable ejection force matter. The engraved characters support component identification during assembly, maintenance, or changeover—especially in multi-cavity tooling.

Scenario 1 – Automotive connector housings: In connector and small electronic-part housings, stable rectangular guidance helps prevent pin skew under cyclic ejection. The SKH51 variant is suited for frequent cycles where wear resistance at the pin/contact surfaces supports consistent ejector behavior.

Scenario 2 – Medical device housings: For molded housings requiring traceable tooling parts, the WOS-based designation engraving enables field-level identification. Concave engraving (including sequential numbering) is practical when multiple similar ejector components must be distinguished.

Scenario 3 – Precision consumer electronics inserts: The controlled P/W fit range supports tight ejector layout, reducing misalignment risk that can otherwise cause uneven stripping.

• Rectangular guidance improves alignment during ejection
• Engraving improves traceability for mold maintenance
• SKH51 supports durability under repeated cycles

Steel grade: JIS Standard SKH51 (high-speed steel) is used for ejector pin applications requiring elevated wear resistance. In common industry cross-references, SKH51 is often associated with the AISI M2 family due to its high-carbon, high-alloy HSS character.

Material performance: With appropriate heat treatment, SKH51 provides a favorable balance of wear resistance and toughness. In ejector systems, the trade-off is typical of HSS tools: pushing hardness improves abrasion resistance but requires careful control of toughness to avoid chipping under shock loads.

• Heat treatment state (typical for SKH51 ejector pins): quenched and tempered to achieve target hardness for service
• Hardness: exact HRC value is not provided in the specification data; hardness should be validated to match your expected ejection pressure and wear conditions
• Manufacturing: precision machining for rectangular guidance geometry and controlled dimensioning for the P/W fit

If alternative steels are offered for the same geometry, SKH51 is typically selected when wear resistance is prioritized over maximum shock toughness.

Step 1: Match the shaft diameter and tip geometry. Select the ejector pin size based on D (shaft diameter) = 2 ~ 10.5 mm, then choose P (Tip) = 0.8 ~ 5 mm and W (Tip) = 0.3 ~ 0.7 mm within the available ranges for your ejector layout.

Step 2: Confirm length for travel requirements. Use L (L dimension) = 40 ~ 250 mm or the listed alternate range (50 ~ 250 mm) when applicable. The pin length should cover the expected stroke and allow secure engagement in the ejector support structure.

Step 3: Validate the rectangular guidance fit. The data indicates P/W dimension control (0 / -0.005), meaning the fit may be up to nominal and slightly undersize by 0.005 mm. Ensure your mating ejector block/core pocket design accounts for this tolerance to avoid looseness or binding.

• Dimension N = 23 ~ 40 mm should align with your guidance/support geometry
• Character engraving is fixed as WOS designation, so it doesn’t change the critical fit dimensions
• Verify that the total ejector stack height accommodates L and N