Fundamental design rules
These rules ensure successful injection molding production and minimize defects.
Wall thickness
- Uniform thickness: 0.5-4 mm
- Gradual transitions
- Avoid thick sections
Draft angles
- Minimum 0.5°-1°
- Deeper cores: 1-3°
- Texture: extra angle
Fillets
- Avoid sharp corners
- Radius: 0.5-1.5 mm
- Limit stress concentration
Material flow optimization
Gate placement
- At the thickest section
- Symmetrical filling
- Minimal flow length
Weld lines
- Predictable locations
- Strength considerations
- Cosmetic impact
Common defects and solutions
Defects
- Sink marks - thick sections
- Warping - uneven cooling
- Flash - excessive pressure
- Short shots - incomplete filling
Solutions
- Uniform wall thickness
- Symmetrical design
- Correct gate location
- Adequate draft angles
Uniform wall thickness, symmetry and correct gate placement are the key to defect-free injection molding.