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Cantilever Snap Fit: Injection Molding Design Rules
Cantilever snaps combine beam flex and hook undercut with mold release constraints.
DFM
Cantilever snaps deflect once during assembly
Beam length, thickness, and undercut depth set feel and retention.
Cantilever snaps are hooks on a flexible beam. Mold release often needs lifters or slides on internal hooks.
Over deflection cracks the beam. Under deflection falls off in service.
Draft on beam sides reduces drag during ejection before the snap even gets assembled.
DFM
Quote this rule with your CAD upload
NetProto DFM review flags these geometry patterns before steel is ordered.
- Call out draw direction and cosmetic faces on the model.
- Note resin family even when the grade is not final.
- Tighten tolerances only on mating features that need them.
Snap design
Document before mold steel
Mold shop needs hook depth and beam geometry.
Retention force target or qualitative click requirement
Mating part material if dissimilar
Expected assembly cycles for testing
Hidden face for hook undercut and lifter witness
Related rules
Design guide
Jump to sibling rules before you freeze CAD.
DFM article
Long form engineer guide.
DFM articleAnnular snap fit
Circular snap alternative.
Annular snap fitLifters
Internal hook release.
LiftersDraft angle
Beam release from mold.
Draft angleVisual reference
Molding context for this rule
Images from the Forge media library illustrate typical programs.
Injection molded part design review on CAD
Injection molded part design review on CAD
Plastic housing with ribs and bosses
Plastic housing with ribs and bosses
Engineer measuring molded component
Engineer measuring molded component
FAQ
Cantilever snap questions
Can snaps be molded without lifters?
Sometimes with external undercuts eliminated or split parts.
Does glass fill work for snaps?
Glass filled resins are stiffer and more brittle for flex features.
Should I prototype snaps by printing?
Print helps feel, but molded flex depends on gate, orientation, and resin lot.
Next step
Quote snaps with full CAD
Upload hook geometry and assembly direction for DFM.