SKH51 Steel Pin-Point Gate Bushings - Round Gate Transition

Pin-point gate bushings made from SKH51 are used at the transition between the sprue and cavity to produce a controlled, repeatable gate. The round gate transition variant helps stabilize molten flow as it concentrates into a small gate opening, which is critical for parts that require consistent knit-line behavior and clean gate appearance.

• Automotive connector and sensor housing molds: Use these bushings to maintain precise gate formation and reduce localized wear at the gate area through hardened steel, supporting long-run production.
• Medical device housings with tight cosmetic requirements: The controlled pin-point geometry supports smooth flow into fine features, improving the likelihood of stable part-to-part gate quality.
• High-precision consumer electronics enclosures: The tight P dimension tolerance ±0.01 supports accurate positioning for reliable assembly in precision gate systems.

SKH51 steel pin-point gate bushings are designed for gate-area durability and dimensional stability in injection tooling. SKH51 is an equivalent of AISI M2 high-speed steel, known for high hardness and strong wear resistance under cyclic thermal and mechanical loading.

• Hardness & wear vs. toughness: In typical mold tooling usage, SKH51 is expected to be hardened to a high hardness level (often in the high-HRC range) for wear resistance at the gate tip. This high hardness improves resistance to erosion, while requiring attention to toughness trade-offs compared with lower-alloy steels.
• Heat treatment state: These bushings are supplied in a hardened condition suitable for precision gate formation; post-processing typically focuses on dimensional stability and surface finishing rather than re-hardening.

If you need higher impact toughness, consider alternative mold steels, but you would generally give up some gate-tip wear resistance relative to SKH51.

Select the bushing size by matching the gate tip dimensions and overall geometry to your mold cavity/core gate requirements. Start with the shaft/tip diameter P (given as 0.3 to 1.2 mm) to define the actual pin-point gate opening controlled at the cavity interface.

• Outer diameter D: Choose D = 2 to 8 mm so the bushing fits the corresponding bore in the sprue/gate insert or guide block.
• Length matching (B and L): Confirm the stack-up length using B = 3 to 5, 4 to 6, 5 to 9, 5 to 30, 5 to 35, 5 to 50 mm (length excluding head and tip) and L = 6 to 20, 8 to 25, 10 to 40, 15 to 60 mm (overall L dimension range per configuration).
• Tip geometry: Use C (tip length), R (tip radius), and taper angle A = 1° to 3° to align the round gate transition profile to your gate land design.

Because P tolerance is ±0.01, use that value when checking gate opening targets and assembly fit around the gate bushing to ensure stable pin-point gating.