How to design for extrusion: 10 tips that reduce cost and lead time

6 min read

Good extrusion design starts before the die is cut. A few choices early on cut tooling cost, improve yield, and shorten lead time. Here are ten that consistently pay off.

1. Keep wall thickness uniform. Even walls fill and cool evenly, which reduces twist, warping, and die wear — and lets the press run faster.
2. Use generous internal and external radii. Sharp corners concentrate stress on the die and resist metal flow; rounding them improves quality and extends tool life.
3. Design the cross-section symmetrically. Balanced metal flow puts less stress on the die and helps the profile come off the press straight instead of twisting.
4. Limit deep, narrow channels and high tongue ratios. Long, thin tongues between channels are fragile in the die and prone to breakage; widen the opening or reduce the depth where you can.
5. Specify realistic tolerances. Hold standard extrusion tolerances across most of the profile and tighten only the few features that truly need it — every tight callout adds cost.
6. Stiffen with ribs instead of thick walls. Ribs add rigidity where you need it without the extra weight, material cost, and uneven cooling that come with thickening a whole wall.
7. Keep the profile within a smaller circumscribing circle. A tighter circle lets the part run on a smaller, less expensive press and generally lowers cost per pound.
8. Build in self-locating features, snap-fits, and screw bosses. Designing these into the extrusion cuts secondary machining and assembly downstream.
9. Account for the finish in the design. Anodizing reveals die lines and surface variation, so plan which faces are visible and orient critical surfaces accordingly.
10. Involve the extruder early. A quick review of your drawing before the die is cut confirms manufacturability and catches cost drivers while changes are still cheap.