Concave Engraving Straight Core Pins (SKH51 Steel) - Sequential Designation

Concave engraving straight core pins are used in injection mold tool assemblies where the mold needs reliable identification and repeatable part ejection. The concave, laser/engraved character profile supports clear, durable sequential numbering, helping technicians track cavities, inserts, and maintenance history.

• Automotive and appliance connector molds: In high-volume production, the pin’s engraving aids fast cavity/orientation verification during setup, while the straight core-pin form supports stable ejection alignment.
• Medical device and diagnostic housing molds: Sequential designation helps control assembly and traceability of tooling components between production lots, reducing mix-ups during requalification.
• Multi-cavity die sets: Where multiple cores/plates are handled together, engraved numbering improves housekeeping and inspection, and the pin’s hardened SKH51 base material helps resist wear from repeated cycles.

This variant is suited because SKH51 hardening steel combined with concave engraving maintains readability and dimensional stability under regular mold handling.

SKH51 is a hardening steel widely used for tooling surfaces that demand strong wear resistance. In practical toolmaking terms, SKH51 is comparable to AISI M2 class high-speed steel behavior, offering a good balance of hardness and tool life.

• Hardness: The product is made from SKH51 hardening steel that is quenched for wear-resistant performance (specific HRC value is not provided in the data).
• Wear vs. toughness trade-off: Higher hardness improves abrasion resistance during repeated core/pin contact cycles, while the hardened condition can reduce impact toughness compared with lower-alloy steels.
• Surface durability: The engraved region benefits from the same hardened steel properties, helping keep character definition under frequent ejection and handling.

If you compare with softer core-pin steels, SKH51’s hardened state typically extends service life, but design should account for the usual reduced toughness of hardened tooling steels under shock loads.

Select dimensions by matching the pin to the core/cavity interface and the required engraving designation fit. Use the shaft diameter selection in the range D/P: 0.6 ~ 10 mm (also referenced as No. (nominal diameter): 0.8 ~ 10 mm), and choose the length L based on the needed engagement depth: 10 ~ 100 mm, or extended options 10 ~ 120 mm / 10 ~ 150 mm.

• Tolerance matching: Shaft diameter tolerance is listed as 0/-0.005, -0.01, -0.02. For tighter locating fits, favor the tighter negative tolerance value when pairing with reamed or ground bores.
• Engagement length: Ensure the chosen L provides sufficient support to prevent bending during ejection, especially in deeper core assemblies.
• Fixed engraving spec: Engraving character designation is fixed as ※Designation by WOS, so dimension selection focuses on fit (D/P and L), while character format remains standardized.

When designing for ejection control, verify bore length and clearance so the tolerated shaft diameter achieves the intended positional stability without excessive friction.