Die Casting vs Aluminum Extrusion: How to Choose

Die casting and aluminum extrusion both produce aluminum parts, but they solve different design problems. Die casting is better for complex three-dimensional shapes with bosses, ribs, housings, covers, and integrated features. Extrusion is better for long constant cross-section profiles such as rails, frames, heat sink fins, and structural beams.

For buyers, the decision should start with geometry. If the part has the same cross-section along its length, extrusion may be best. If the part needs complex local features, die casting may reduce assembly and machining.

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Quick Comparison

Factor	Die Casting	Aluminum Extrusion
Geometry	Complex 3D shapes	Constant cross-section profiles
Tooling cost	Higher die casting die cost	Lower extrusion die cost
Part length	Limited by machine and tool	Strong fit for long parts
Integrated bosses and ribs	Strong fit	Usually requires machining or assembly
Surface finish	As-cast plus finishing	Good profile finish
Secondary machining	Often for critical features	Often for holes, cuts, and slots
Production volume	Best for medium to high volume	Flexible for many volumes

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When to Choose Die Casting

Choose die casting when the part needs:

1. Mounting bosses
2. Integrated brackets
3. Complex ribs and pockets
4. Sealing faces
5. Curved or enclosed housing geometry
6. Multiple assembly features in one part
7. High-volume repeatability
8. Reduced part count

Examples include motor housings, electronics enclosures, pump bodies, lighting housings, and structural brackets.

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When to Choose Aluminum Extrusion

Choose extrusion when the part needs:

1. A long straight profile
2. Constant cross-section geometry
3. Rails, frames, channels, or beams
4. Straight heat sink fins
5. Lower tooling cost for profile production
6. Cut-to-length flexibility
7. Secondary machining for holes and slots

Extrusion is often strong for structural frames and heat sinks with simple linear geometry.

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Cost and Tooling Trade-Off

Cost Area	Die Casting	Extrusion
Tooling investment	Higher	Lower
Per-part cost at volume	Low when geometry is integrated	Low for simple profiles
Machining cost	Can be low if features are cast in	Can rise with many holes and pockets
Assembly cost	Can reduce part count	May need brackets or fasteners
Design changes	Tool changes can be expensive	Profile changes require die update

The cheapest process is the one that reduces total landed cost, not just tooling cost.

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RFQ Checklist

Send the supplier:

• 3D model and 2D drawing
• Annual volume
• Part length and size
• Load requirements
• Machined features
• Surface finish
• Assembly method
• Target cost and tooling expectation

KastMfg can review whether a part is better suited for die casting, extrusion, machining, or a hybrid assembly. Submit drawings through the RFQ page.

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FAQ

Is die casting stronger than extrusion?

Not automatically. Strength depends on alloy, geometry, heat treatment, load path, and defects. Extrusion can be strong for long profiles, while die casting can integrate complex load-bearing features.

Is extrusion cheaper than die casting?

Extrusion tooling is usually cheaper, but total cost depends on machining, assembly, part count, finish, and volume.

Can a part combine extrusion and die casting?

Yes. Many products use extruded rails or frames with die cast end caps, corner nodes, brackets, or housings.

Which process is better for heat sinks?

Extrusion is often better for simple straight-fin heat sinks. Die casting is better when the heat sink also needs housing features, bosses, sealing, or complex geometry.