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Standard Tolerances: Injection Molding Design Rules
Commercial molding tolerances differ from machined metal defaults.
DFM
Tighten only where the assembly needs it
Rules NetProto DFM review checks against before steel is ordered.
Every tight tolerance can add tooling or inspection cost.
Use GD&T on mating features instead of blanket decimal tolerances.
CAD checklist
Send this with your upload
Missing DFM inputs delay qualified quotes.
Mating features identified
Tolerance block or GD&T frame
Related rules
Design guide
Jump to sibling rules before you freeze CAD.
DFM article
Long form engineer guide.
DFM articleWall thickness
Design rules for wall thickness.
Wall thicknessDraft angle
Design rules for draft angle.
Draft angleRib design
Design rules for rib design.
Rib designFAQ
Common questions
Are metal tolerances valid on plastic?
Often no. Use molding appropriate bands on non critical dims.
Next step
Upload CAD for DFM-aware quoting
One hardened steel tool quote with piece price on the same upload.