When specifying aluminium tube for a critical application, the manufacturing method matters just as much as the material itself. Two common routes are impact extrusion and cold drawing. Both produce seamless aluminium tube, but they behave very differently in terms of precision, mechanical performance, and suitability for demanding environments.

Here’s a clear, practical guide to help you choose the right option.

What is impact extrusion?

Impact extrusion is a cold-forming process in which a slug of aluminium is struck at high speed by a punch inside a die. The metal flows plastically – either forward, backward, or both – to produce a hollow or semi-hollow shape in a single stroke.

The process is fast and highly repeatable. Because it can form a closed or partially closed end as part of the component, it removes the need for certain secondary operations.

The work-hardening that occurs during cold forming gives impact extruded parts good mechanical strength, and wall thickness can be varied within a single component. However, the process requires a bespoke die, which carries a meaningful upfront tooling investment.

It is best suited to high-volume production of components with integrated closed ends, such as aerosol canisters, fire extinguisher cylinders, and pressurised housings.

Common alloys include 1000, 3000 and 6000 series.

What is drawn tube?

Drawn tube is produced by cold drawing an aluminium tube through a precision die to reduce its diameter and wall thickness to the required dimensions.

The tube may be drawn over a mandrel, which precisely controls the internal bore, or drawn without a mandrel where less critical internal tolerances are acceptable.

The process produces open-ended, uniform cross-section tube with excellent straightness, concentricity, and surface finish. Multiple drawing passes allow very tight tolerances to be achieved on outer diameter, inner diameter, and wall thickness.

Drawn tube is available in a wide range of standard sizes and can be produced to bespoke dimensions.

At Spartal, we work with alloys 1000, 3000 and 6000 chosen for their strength, corrosion resistance, machinability, and formability. Tube can be supplied in straight lengths, cut to length, or further processed.

How the two processes compare

	Impact extruded	Drawn tube
Cross-section	Variable along length	Uniform along length
End condition	Closed or partially closed	Open both ends
Wall thickness	Can vary within part	Consistent throughout
Tolerances (OD/wall)	Good	Excellent, very tight achievable
Surface finish	Very good	Excellent
Tooling investment	Higher (bespoke die required)	Lower
Typical volumes	Medium to very high	Low to very high
Lead time (prototyping)	Longer	Shorter
Further machining suitability	Moderate	Excellent

Where drawn tube excels

Drawn tube is the natural choice for structural, fluid-carrying, and precision engineering applications. Its key strengths are dimensional accuracy, surface quality, and versatility.

Because the process produces a consistent cross-section along the full length with tight tolerances, drawn tube performs well where concentricity, bore finish, and straightness are critical. It machines cleanly, bends predictably, and accepts surface treatments such as anodising without complication.

It is also highly accessible across a wide volume range, with no significant tooling commitment, making it ideal for both development and production.

Typical applications include:

• • Hydraulic and pneumatic cylinders

• • Aerospace and motorsport structural tube

• • Heat exchanger and thermal management tubing

• • Precision shafting and bearing housings

• • Medical device components

• • Fluid transport and instrumentation lines

• • Defence and industrial actuation systems

When impact extrusion may be more appropriate

Impact extrusion has clear advantages in certain cases.

If your component requires a closed or integrated base, such as a canister or pressurised vessel, impact extrusion can produce that form in a single operation without welding.

For very large production volumes of fixed designs, the per-unit cost can also be highly competitive once tooling is in place.

However, for open-ended components, precision bore requirements, or parts requiring further machining, drawn tube typically offers a better technical and commercial solution.

Alloy selection for drawn tube

Choosing the right alloy is critical.

• • 6063: versatile, good corrosion resistance, widely used

• • 6060: similar to 6063 with slightly different strength profile

• • 6082: higher strength, ideal for structural and load-bearing applications

All materials are fully traceable and supplied with EN 10204 3.1 certification as standard.

A note on tolerances and standards

Drawn tube is typically produced to EN 754 standards in the UK and Europe, covering tolerances for diameter, wall thickness, and straightness.

Where tighter tolerances are required, Spartal can work to customer-specific requirements and advise on the most cost-effective solution.

Correct specification is key. Over-specifying increases cost, while under-specifying risks performance.

Conclusion

Impact extrusion and drawn tube serve different purposes.

Impact extrusion is ideal for closed-end, high-volume components.
Drawn tube is the preferred choice for precision engineering, structural, and fluid applications, offering tight tolerances, excellent surface finish, and flexibility.

At Spartal, drawn tube is what we do. We supply standard and bespoke sizes, offer full material traceability, and provide technical support from specification through to delivery.

If you are working on a new component or reviewing an existing design, our team is always happy to help.