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5-axis CNC milling drawing: Al 7075-T6 block with pockets, toolpath and dimensions
Design Guide · Plastic Ribs

Ribs. Stiffening features. Without thick walls.

Plastic part rib design. Ribs add stiffness without thick walls (which cause sink marks). Specific rules for rib thickness, height, draft, fillets.

Design for manufacturingWuxi, ChinaMOQ 1 partDFM review included

Key principles.

60% wall

Rib 60% of base wall. Prevents sink marks at rib base.

3× wall max

Rib height ≤ 3× wall thickness. Above this, draft and shrinkage issues.

0.5° per side

Standard 0.5° draft per side. Allows ejection from mold.

0.25× wall

Generous fillet at rib base reduces stress concentration.

3× wall

Rib center-to-center 3× wall thickness minimum.

Significant

Rib pattern stiffness 2-5× plain plate. Without weight or sink marks.

FAQ

Add stiffness without thick walls. Thick walls cause sink marks. Ribs solve this.

Cross ribs (X pattern) gives 2-3× stiffness vs parallel. Choose per loading direction.

Center-to-center 3-5× wall thickness. Tighter spacing = stiffer but more material.

Rib thickness 60% of wall = critical rule. Going thicker causes sink. Fillet base helps.

Sufficient draft (0.5° each side) and fillets. Rib must release cleanly from mold.

Cross-rib + edge stiffening + thickness optimization for max stiffness per material.

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5-axis CNC milling drawing: Al 7075-T6 block with pockets, toolpath and dimensions

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