Sprue-Related Components
Guide bushings, sprue lock bushings, and string prevention caps — essential accessories for sprue bushing assemblies.
Products — 3 Variants
Guide Bushings for Sprue Bushings
Guide Bushings for Sprue Bushings
Sprue Lock Bushings - Headed or Straight
Sprue Lock Bushings - Headed or Straight
Caps for Preventing Sprue Strings
Caps for Preventing Sprue Strings
Compare Sprue Accessories
Three accessories solve different sprue bushing challenges:
| Component | Function | Material | When Needed |
|---|---|---|---|
| Guide Bushing (SBGN) | Centers sprue bushing in plate bore | SUJ2 (52100) steel | When bore has clearance — eliminates radial play |
| Sprue Lock Bushing | Retains sprue in runner during mold opening | SKD61 | When sprue doesn't pull cleanly from the bushing |
| String Prevention Cap | Prevents resin stringing at nozzle/sprue | Steel | When processing stringing-prone resins (PA, PET, TPU) |
Accessory guide: For a complete selection reference, see our Sprue Accessory Guide.
Pairing with Sprue Bushings
Each accessory pairs with specific sprue bushing configurations:
- Guide bushings — Match bore OD to sprue bushing shaft diameter (D). Install in the mold plate bore before the sprue bushing.
- Sprue lock bushings — Install in the moving half of the mold, opposite the sprue bushing. Match bore to sprue diameter at the large end.
- String prevention caps — Attach to the sprue bushing nozzle touch surface. Match SR to sprue bushing SR.
Troubleshooting: Sprue Stringing Problems
Sprue stringing is the most common problem solved by these accessories:
| Problem | Likely Cause | Component Solution |
|---|---|---|
| Thin string between nozzle and sprue on every cycle | Nozzle temperature too high or insufficient suck-back | String prevention cap or string eliminator sprue bushing |
| Sprue sticks in the bushing (doesn't pull out) | Taper angle too narrow, or draft insufficient | Sprue lock bushing in moving half creates positive pull |
| Sprue bushing shifts laterally between shots | Bore clearance too large, no radial constraint | Guide bushing centers and constrains radial movement |
| Nozzle misalignment causing resin leakage | Sprue bushing not centered in plate bore | Guide bushing + verify locating ring centering |
Full troubleshooting: For a complete diagnosis and solution guide, see our Sprue Stringing Prevention Guide.
About Sprue-Related Components
These accessories complete the sprue bushing assembly. While the sprue bushing itself handles the primary resin channel, guide bushings, lock bushings, and string caps solve the secondary problems of alignment, retention, and stringing that affect production reliability.
Frequently Asked Questions
What causes sprue stringing and how do I prevent it?+
Do I need a guide bushing if my sprue bushing is bolt-fixed?+
Headed vs straight sprue lock bushings — which should I use?+
Engineering Resources
Need a Custom Quote?
Specify your sprue bushing shaft diameter (D), SR value, and the problem you're solving (stringing, alignment, retention). We'll recommend the right accessory combination.