Runner
Cold runner scrap becomes regrind.
RunnerGlossary
What Is Regrind? Injection Molding Explained
Regrind is recycled molding scrap ground back into the virgin feed stream.
Glossary
Regrind is sprue, runner, and scrap ground back into the feed stream
Regrind percentage shifts melt behavior and properties on sensitive programs.
Each heat history can degrade polymer chains if regrind limits are ignored.
Optical, medical style, and tight color programs often cap regrind aggressively.
State regrind limits in material and quality requirements on qualified production RFQs.
Glossary
How regrind shows up on real programs
Library photos illustrate molding and tooling context for this term.
- Use the term in RFQs with geometry and material context, not in isolation.
- Link to the design guide when the term affects steel or part design.
- Upload CAD when the term changes tooling scope or piece price.
Quality
Regrind notes for production RFQs
Clarify these before color and property disputes at T1.
Maximum regrind percentage allowed
Whether regrind must stay within same resin lot family
Color match sensitivity across regrind ratios
Impact or optical tests required when regrind changes
Go deeper
Where this term connects
Each link is a different angle on the same program, not a duplicate definition.
Sprue
Sprue slug regrind on cold runner tools.
SpruePurging
Color changes before regrind mixes wrong resin.
PurgingCold runner
More regrind source than hot runner.
Cold runnerVisual reference
Photos from molding and tooling programs
Images are selected from the NetProto Forge media library for this topic.
Injection molded production parts on a tray
Injection molded production parts on a tray
Engineer reviewing a molded part drawing
Engineer reviewing a molded part drawing
Plastic housing components from a steel tool
Plastic housing components from a steel tool
FAQ
Regrind questions
Does NetProto allow regrind?
State limits in material and quality requirements on your RFQ.
Can regrind cause splay?
Contamination and moisture on regrind streams can show cosmetic defects.
Is 100 percent regrind realistic?
Rare on cosmetic production. Most programs blend virgin and regrind.
Next step
Define quality on the RFQ
Upload CAD with material and regrind limits for production quotes.