How to design parts optimized for the aluminum extrusion manufacturing process?

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Five key rules for extrusion design: (1) uniform wall thickness throughout the profile (0.8-6mm, vary no more than 50% between sections), (2) inside corner radii of 0.5mm minimum, (3) avoid deep narrow channels (depth-to-width ratio under 3:1), (4) symmetrical profiles extrude faster and more consistently, and (5) balance solid and hollow sections. Following these guidelines reduces die cost by 20-40% and improves extrusion speed by 30%.

Wall Thickness Guidelines

Uniform wall thickness is the most important design rule. The molten aluminum flows through the die at the same rate in all sections only if wall thickness is consistent. Recommended minimum wall: 0.8mm for aluminum 6063, 1.2mm for 6061. Maximum wall: 6mm for most applications. If your design has different wall sections, transition gradually over at least 3x the thickness difference. Variations exceeding 50% should be avoided.

Corner Radii and Fillet

Sharp corners concentrate stress and make aluminum flow unevenly through the die. Minimum inside radius: 0.5mm (0.020"). Minimum outside radius: 0.8mm (0.030"). Generous radii (1-2mm) extend die life and improve material flow. For decorative profiles, larger radii produce a more aesthetically pleasing appearance. All internal corners should have radii -- sharp V-shaped grooves are difficult to extrude.

Profile Symmetry and Balance

Symmetrical profiles extrude faster and more consistently. The die opening should be balanced around the center axis. Unbalanced profiles tend to bend or twist as they exit the die. If asymmetry is unavoidable, design the die with balancing features or specify additional straightening operations. Solid sections should be distributed evenly around the center -- avoid concentrating all mass on one side.

Hollow Sections and Screw Bosses

Hollow sections require more complex dies with mandrels and are more expensive than open profiles. Design hollow sections only when necessary (e.g., enclosed wireways, sealed chambers). Screw bosses and attachment features should be placed on the outer surface where possible. Internal threaded features are difficult to extrude -- use drop-in T-nuts or drill and tap after extrusion.

Why Choose SOMI Custom Parts

At SOMI Custom Parts, our engineering team provides free DFM analysis on every extrusion profile design. We review your cross-section against extrusion design rules and suggest modifications to improve manufacturability, reduce die cost, and speed up production. We also provide design support for secondary operations including CNC machining of end details, drilling and tapping, anodizing, and assembly.

Case Study

A customer submitted an asymmetric extrusion profile with wall thicknesses ranging from 1mm to 4mm, a sharp internal corner, and a deep narrow channel. SOMI's DFM review recommended: smoothing the wall transitions (1.5-2.5mm max variation), adding a 0.8mm radius at the sharp corner, and widening the narrow channel slightly. Die cost decreased from $2,800 to $1,600, extrusion speed improved by 35%, and the profile had minimal distortion.

Industry Data

Proper DFM in extrusion reduces die cost by 25-40% and increases extrusion speed by 20-40% on average (Aluminum Extruders Council Design Guide, 2025). The most common extrusion design mistake is non-uniform wall thickness, accounting for 60% of first-pass die rejections. Profiles designed with DFM principles have 85% first-pass success rate versus 45% for designs without DFM review.