Designing aluminum extrusions is both an engineering challenge and an optimization exercise. A profile may look feasible in CAD, but manufacturability determines whether it can be extruded consistently, cost-effectively, and within tolerance. That is where Design for Manufacturability, or DfM, becomes essential.
For OEMs, product engineers, and industrial designers, the understanding of DfM principles specific to extrusion ensures that aluminum profiles not only satisfy performance and structural requirements but are also manufacturable in volume in an effective and repeatable way.
At Can Art Aluminum Extrusion Canada Inc., our engineering teams work closely with designers in the early development phase to fine-tune profile geometry, assess material behaviour, and avoid expensive late-stage redesigns. Below, we highlight the five fundamental DfM principles behind successful design in aluminum extrusion.
- Profile Simplicity and Section Uniformity
Why simplicity matters
Most manufacturable extrusion profiles balance functionality with geometric simplicity. Complex profiles with abrupt thickness changes, deep cavities, or intricate contours are harder to extrude, more susceptible to distortion, and more expensive to make.
Uniform wall thickness
A fundamental guideline in the design of aluminum extrusions is to maintain uniform wall thickness wherever possible. Uniformity:
- Consistent material flow through the die
- Reduced risk of twisting, bowing, or uneven cooling
- Better dimensional accuracy and repeatability
Where variation is inevitable, transitions must be gradual, not abrupt. Heavy walls alongside thin walls increase die stress and also produce uneven metal flow.
Minimum wall thickness
Minimum wall thickness will be dependent on the alloy, the temper required, and the complexity of the shape. Typical minimum wall thickness for the 6000-series alloys used in structural, architectural, and automotive applications ranges from 1.0 mm to 2.5 mm, depending upon geometry. Thinner walls are possible, but die design must be carefully executed.
- Management of Hollows, Voids and Tongue Ratios
Profiles that enclose a void (tubes, channels, box sections) must have porthole or bridge dies which create an internal weld seam. While the welds are structurally adequate for most purposes, they must be accounted for when load-bearing and/or highly cosmetic parts are being designed.
Tongue ratio
The tongue ratio is a critical DfM parameter that governs the feasibility of hollow features. It describes the height-to-thickness ratio of die tongues forming internal cavities.
High tongue ratios increase the likelihood of die breakage or premature wear. To ensure manufacturability:
- Avoid extremely deep, narrow hollows
- Use radiused transitions, rather than sharp corners
- Keep internal webs proportional and accessible
- Where possible, consider converting extremely complex hollows into simpler open shapes that can be closed using post-extrusion assembly.
- Incorporating Functional Features: Screw Bosses, Snap Fits, and Channels
Aluminum extrusions provide great flexibility in integrating features directly into the profile design, which reduces machining and secondary operations.
Screw bosses
Bosses shall be sized to allow consistent metal flow. Too-large bosses cool unevenly and may shrink or distort; too-small ones may collapse under extrusion pressure. Circular bosses are preferable over complex shapes.
Snap fits and interlocks
Snap features are used in consumer, industrial, and architectural extrusions. When designing snap fits:
- Avoid stress concentration by maintaining uniform wall sections.
- Avoid crack initiation points by using radii.
- Avoid extremely thin or long snap arms that may warp.
Mounting channels and tracks
Dimensions for T-slots, wiring channels and alignment features need to have radii and draft angles appropriate for maintaining extrudability and minimizing die wear.
- Dimensional Accuracy, Tolerances, and Structural Integrity
Realistic tolerances reduce cost
Close tolerances complicate tooling, reduce extrusion speed, and raise the cost of production. Aluminum extrusions already have established tolerances according to profile type and alloy (see Aluminum Association standards, for example). Over-specification of tolerances beyond what is typical for the industry dramatically affects cost.
Where precision is critical, such as in mating parts, sliding mechanisms, or automotive assemblies, the critical-to-function dimensions should be highlighted. Secondary machining can handle ultra-tight tolerances more economically than trying to fully achieve them within the extrusion process.
Structural integrity
Besides depending on wall thickness, structural performance also depends on geometry:
- Rounded corners improve metal flow and reduce stress
- Multichamber designs increase stiffness
- Ribs and webs add strength without excess weight
FEA can be utilized in the design phase to ensure that profiles will meet load, torsion, and impact requirements.
- Cost Reduction through Smart DfM Decisions
Material and processing decisions can greatly affect overall cost.
Material selection
Common 6000-series alloys include 6061, 6063, and 6082, offering a balance of strength, corrosion resistance, and extrudability. Alloy choice affects:
- Minimum wall thickness
- Surface finish quality
- Extrusion speed
- Machining behaviour
Choosing the right alloy early reduces cost and lead time.
Post-extrusion finishing and fabrication
A profile that requires extensive machining, welding, or finishing often represents a design opportunity. Integrating additional functionality into the extrusion, without compromising DfM rules, reduces the downstream cost.
Assembly considerations
Various assembly efficiency-enhancing features in the product, such as alignment tabs, interlocks, and mounting channels, all reduce labour time and simplify multi-part systems.
Common Questions About Designing for Aluminum Extrusions
How do you design for aluminum extrusion?
The design for manufacturability focuses on uniform wall thickness, simplified geometry, appropriate radii, balanced hollows, realistic tolerances, and integration of features supporting metal flow and longevity of the dies.
What is the minimum wall thickness for an aluminum extrusion?
For the 6000-series of alloys, typical minimum wall thickness ranges from 1.0 to 2.5 mm depending on profile complexity and application. Walls thinner than this might be possible but require a more specialized die design.
How can I reduce the cost of my aluminum profile?
Reducing complexity, avoiding unnecessary tight tolerances, minimizing heavy masses, selecting the right alloy, and integrating functionality into the extrusion can significantly reduce cost.
What are the key principles of DfM for aluminum extrusions?
The core principles include profile simplicity, wall uniformity, controlled hollow design, functional feature integration, realistic tolerances, material optimization, and considering downstream processes during the initial design phase.
Conclusion
Design for Manufacturability ensures that aluminum extrusion profiles perform as intended, meet structural and dimensional requirements, and can be reliably produced at scale. By applying these principles early in the engineering process, designers can avoid unnecessary cost, reduce iteration cycles, and create profiles that maximise the advantages of aluminum extrusion technology.
