Sprue Bushings
Steel sprue bushings and related components for injection mold nozzle-to-runner connections. Bolt fixing and shoulder mounting types in multiple flange thicknesses, with string eliminator and cooling circuit options.
Sprue Bushing Types
Steel Sprue Bushings
Bolt fixing and shoulder type sprue bushings in 8–20 mm flange thicknesses. Standard, string eliminator, environmentally friendly, and cooling circuit options.
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Sprue-Related Components
Guide bushings, sprue lock bushings, and string prevention caps for sprue bushing assemblies.
View 3 ProductsHow to Choose a Sprue Bushing
Follow these steps to narrow down your sprue bushing selection:
Determine Mounting Method
Bolt fixing — Secured with bolts through the flange. Most common, easiest to replace.
Shoulder type — Press-fit using the flange shoulder. Compact but harder to remove.
Select Flange Thickness
Match to your mold's locating ring counterbore depth: 8 mm, 10 mm, 15 mm, or 20 mm. Most common: 10 mm.
Check Special Requirements
String eliminator — Prevents resin stringing at the nozzle touch. Choose if you have stringing issues.
Cooling circuit — Built-in cooling channels for heat management. Choose for high-temperature or fast-cycle molds.
Extended nozzle — For non-standard nozzle protrusion lengths.
Match Nozzle Specifications
Verify SR (nozzle touch radius) and P (sprue port diameter) match your injection machine nozzle.
Sprue Bushing Key Parameters Explained
Critical Dimensions
- SR (Nozzle Touch Radius) — The spherical radius at the nozzle contact surface. Must be slightly larger than the machine nozzle radius to ensure proper seating and prevent resin leakage.
- P (Sprue Port Diameter) — The orifice diameter at the nozzle end. Must be slightly larger than the machine nozzle orifice to prevent resin hang-up.
- A (Taper Angle) — The internal taper of the sprue channel, typically 1–3°. Ensures smooth sprue release during mold opening.
- D (Shaft Diameter) — The outside diameter of the bushing body. Must match the mold's sprue bushing bore.
- Flange Thickness — The thickness of the mounting flange. Must match the locating ring counterbore depth in the mold.
Sprue Bushing + Locating Ring Pairing
Every sprue bushing installation requires a matching locating ring. The key compatibility factors:
- Mounting type match — Bolt-fixing sprue bushings pair with bolt-stopper type locating rings. Shoulder types pair with standard locating rings.
- Bore diameter match — The locating ring center bore must accommodate the sprue bushing shaft diameter (D).
- Machine platen match — The locating ring outer diameter must match the injection machine's platen locating hole.
Frequently Asked Questions
What is the function of a sprue bushing in an injection mold?+
How do I measure sprue bushing nozzle touch radius (SR)?+
Bolt fixing vs shoulder type sprue bushings — which is more common?+
What is the recommended sprue taper angle for different resins?+
Engineering Resources
Sprue Bushing Parameters Explained: SR, Sprue Port, Flange & Taper
Complete parameter reference for sprue bushing selection and specification.
How to Match Sprue Bushings with Locating Rings and Guide Bushings
Compatibility chart and pairing rules for sprue bushing assemblies.
Need Sprue Bushings?
Tell us your nozzle SR, sprue port diameter, and flange thickness requirement — we'll recommend the right sprue bushing and locating ring combination.