Extrusion & Extruded Profiles

What extrusion is for

Extrusion pushes heated material through a shaped die. The result is a part whose cross-section is constant for its whole length — a profile. Nothing about the shape changes as you move along the part, which is both the process’s limitation and the reason it is so economical.

That makes it the right answer for a recognisable set of components:

• Structural rails and frame members — T-slot sections, mounting rails, chassis beams
• Heat sink bodies, where the fins are part of the cross-section
• Trim and edge sections for enclosures, panels and furniture hardware
• Tubes and hollow sections, including multi-port profiles
• Long brackets and mounting strips that are the same shape end to end
• Handles, corners, jointing sections and similar architectural hardware

The rule is simple: if the shape does not change along the length, extrusion is the cheapest way to make it. If it does change — a pocket, a taper, a step, a hole — that feature is machined afterwards rather than extruded.

Extrusion and machining are partners, not alternatives

The framing of “extrusion or machining” is misleading, because most extruded components are also machined.

An extrusion produces the cross-section. It does not produce a finished part. What is usually still needed:

Feature	How it is produced
Length	Cut to size from the extruded length
End faces	Faced or milled square after cutting
Holes and threads	Drilled and tapped on our floor
Flats, steps and slots	Milled into the profile
Notches and cut-outs	Machined where the section changes
Assembly features	Machined to suit the mating component

Those operations are the ones that have to be accurate, and they are where the extruded profile meets the same tolerance discipline as any machined part: ±0.01 mm on precision features with ISO 2768-m as the general tolerance block.

So the production route for a typical extruded component runs: die and extrude, cut to length, machine the ends and features, then finish. The extrusion removes the bulk of the material cost; the machining provides the accuracy. The CNC milling page covers the secondary operations.

Tooling, and the decision it creates

Any non-standard profile needs a die, and the die is quoted separately so you can see the true cost per part across the run.

That creates the one decision that dominates extruded-component economics:

Use a standard profile, or pay for a custom die?

Where a standard section suits the design — or can be made to suit with a small machining change — using it removes the die cost entirely. On a modest quantity that is often a larger saving than anything else available on the part. Where the profile genuinely has to be bespoke, the die has to be justified by the volume, in the same way a casting die or a mould tool is.

Two practical notes follow. First, a design that can be adapted to a standard profile is usually the cheaper design, and it is worth asking before the die is committed. Second, the die is a sunk cost if the programme changes — where the design is still moving or the volume is uncertain, machining from solid keeps the option open until the shape is settled.

Materials

Aluminium is the most common extrusion material, and it is where the process earns most of its use: light, strong for its weight, corrosion resistant with a finish, and easy to anodize. The aluminium grades in our confirmed range cover the standard structural and general-purpose applications, and the full list is on the materials page.

Engineering plastics are also extruded, and the plastic family in our standard range applies — useful where the part has to be insulating, non-corroding or self-lubricating. Plastic profiles hold a different set of tolerances and behave differently with temperature, so the same rule applies: treat the extrusion as the shape and machine what has to be accurate.

Where a drawing calls for a grade outside the confirmed range, tell us what the part has to do rather than assuming a substitution. Material is bought against your drawing for your job, and a grade substitution would be raised with you in writing before anything was cut.

Design rules that decide the price

Wall thickness consistency. A profile with walls of very different thicknesses cools unevenly, which distorts the section and makes the as-extruded tolerance harder to hold. Keeping walls as uniform as the design allows is the single biggest lever on profile quality.

Keep the section simple where you can. Every internal void needs a mandrel and every fine detail needs die work. A section that can be produced with a straightforward die is cheaper and more consistent than one that cannot.

Design the functional faces first. Stating which faces mate, slide, seal or are seen lets the tolerance be placed where it does work. A profile tolerance spread evenly across every surface is more expensive and no more useful.

Plan the machining before the profile is fixed. The features machined afterwards — a flat, a slot, a hole pattern — often need material in the right place. Adding a boss or a thicker web to the profile is free at the die stage and expensive afterwards.

Consider the finish early. Anodizing, powder coating and painting all behave differently on an extruded surface than on a machined one, and anodizing builds a layer. Masking and any post-finish dimensional requirement belong on the drawing — the anodizing page covers the allowance.

Documents, quantities and lead times

Every order ships with a material certificate (MTR) traceable to the mill heat the material came from, plus pre-shipment photos of the actual parts before dispatch. Both are part of the order rather than extras, and what ships is set out on the quality documents page.

Orders start at 50 pieces per profile and material. Samples are available from a single piece in 5–10 days, and production runs in 25–35 days after sample approval. Where a long profile is being cut into several lengths, the quantity is normally quoted per cut length.

How to start

Send the cross-section drawing, the length, the quantity, and a note of which surfaces are functional. Where a standard profile might suit, say so and it will be checked before a die is quoted — that one question is frequently worth more than any negotiation on price. The reply comes back within 24 hours with DFM feedback on wall thickness, machinability of the profile and the machining route for the secondary features.