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Rib Design: Injection Molding Design Rules
Ribs add stiffness without a thick wall, until they become sink generators.
DFM
Size ribs relative to the primary wall
Rules NetProto DFM review checks against before steel is ordered.
Ribs thicker than the wall pull sink to the opposite side.
Spacing matters for venting and steel strength in the mold.
CAD checklist
Send this with your upload
Missing DFM inputs delay qualified quotes.
Rib thickness versus wall chart
Rib height and draft
Sink cosmetic face identified
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 angleUndercuts
Design rules for undercuts.
UndercutsFAQ
Common questions
How thick should ribs be?
Often 50 to 60 percent of nominal wall, program dependent.
Next step
Upload CAD for DFM-aware quoting
One hardened steel tool quote with piece price on the same upload.