SKH51 Steel Pin-Point Gate Bushings Round Gate Transition SR

Pinpoint gate bushings are used to control where polymer first enters the cavity, making them ideal for precision parting lines and small-gate geometries. This steel variant, featuring a round gate transition and an SR tip step, helps maintain consistent gate formation by stabilizing the runner-to-gate flow and the final gate contact area.

• Automotive connector and sensor housings: For small, centrally fed gates, the round transition supports smooth flow from sprue/runner to the pinpoint gate while the SR step promotes repeatable gate size and location across production cycles.
• Medical device housings and caps: Reliable pinpoint gating reduces variation in weld line/jetting behavior and supports repeatability for tight cosmetic and dimensional requirements.
• Electronics enclosures with fine gating: The small-shank positioning supports stable mold locating, helping achieve uniform gating from shot to shot in high-volume molding.

The SKH51 steel construction is suited for these use cases where wear at the gate tip and consistent locating are critical to long-run production stability.

The bushing is made from SKH51 steel, a quench-hardening high-speed/tool steel grade commonly selected for components that require wear resistance at high-contact points. In this type of quenching-and-tempering processing, the material is typically supplied in a hardened condition to balance hardness and toughness.

• Wear resistance: Higher hardness improves resistance to tip wear and erosion during repeated pinpoint gating.
• Toughness trade-off: As hardness increases, impact toughness can decrease; proper tempering is important to avoid chipping at the SR tip step.
• Surface durability: Because the bushing tip directly forms the gate, hardened SKH51 helps maintain the gate profile longer than softer steels.

If comparing grades, consider that pre-hardened/low-alloy steels may offer better toughness but typically lower wear life at the pinpoint gate contact region. SKH51 targets longer service where stable gate geometry is required.

Select the bushing dimensions by matching the sprue/gate transition geometry and the gate land requirements of your cavity design. Start with D (outer diameter)—available as 1.5, 1.6, or 1.8 mm—to ensure the bushing fits the leader bore and maintains proper coaxial alignment with the gate.

• P (tip diameter): Choose from 0.3, 0.3–0.4, or 0.3–0.5 mm depending on the target pinpoint gate thickness/diameter in the parting surface.
• C (tip length): Fixed at 0 to 0.5 mm to control how far the tip projects into the cavity-side gate area.
• L (L dimension): Fixed at 6 to 20 mm to match the mold thickness and runner/sprue length of your tooling layout.
• A (secondary sprue angle): Fixed at 2° for the round transition geometry.

For fit, reference the D tolerance of 0 to -0.005 mm (tight assembly). For P, use the provided tolerance options (±0.01 or ±0.005) to control gate diameter accuracy and repeatability.