Plastic enclosure design guide
Most enclosure problems are designed in before the mold is cut. These are the points worth reviewing early.
Walls and draft
Keep walls as uniform as the structure allows. Thick sections sink and warp; very thin sections may not fill. Add draft on vertical faces so the part releases without scuffing or drag marks.
Bosses and ribs
Bosses should be supported and kept away from thick masses. Ribs add stiffness without adding a solid wall, but they need draft and a fillet at the base.
Snap fits and assembly
Snap fits need room to deflect and a lead-in to assemble. Screw bosses need enough engagement and clearance for the screw. Check the mating part, not just the housing.
Openings and connectors
Connector openings, display windows and ventilation slots need draft and adequate steel around them. Sharp internal corners are stress points and tooling risks.
Cosmetics
Gate location, weld lines, ejector marks and texture all affect the visible surface. Decide which faces are cosmetic and which are hidden before the tool is designed.
DFM checklist
- Draft on walls, bosses and ribs
- Uniform wall thickness
- Radii at internal corners
- Gate away from cosmetic surfaces
- Ejector marks on hidden faces
- Assembly clearance and tolerance stack
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