Guide / Part Design

Plastic Part Design for Injection Molding

Designing parts that are moldable and cost-effective

Design Rules

FeatureRule
Wall ThicknessUniform: 1.5-3mm typical. Avoid changes >2:1 ratio
RibsHeight = 2.5-3x wall, base = 0.5-0.6x wall. Add 0.5-1 draft each side
Draft AngleExterior: 1 deg minimum. Interior: 1.5-2 deg. Textured surfaces: 1 deg per 0.025mm depth
Corner RadiusMin = 0.5x wall thickness (stress reduction). Sharp corners = sink marks
BossOD = 2x ID, wall thickness at base = 0.6x nominal wall. Gusset for tall bosses