Subcontract Anodising for Aluminium Extrusion

If you make aluminium extrusion but don’t run an anodising plant, subcontract anodising gives you the finish without the cost of doing it in-house. Your aluminium components get a hard, corrosion-resistant surface, measured coating thicknesses to BS ISO 7599, and full traceability. No capital outlay on tanks, chemicals or waste treatment.

This covers how subcontract anodising works, what to check before you commit, and how we handle long extrusions at Milturn.

How subcontract anodising works

Anodising is an electrochemical process. It converts the surface of the aluminium into a hard anodic oxide layer that forms part of the metal, not a coating sat on top. That layer improves corrosion resistance and surface hardness, and won’t flake or peel.

Most extruders and fabricators don’t anodise in-house. The plant is expensive to run and only pays back at high volume. So they subcontract it, which gives you:

• The finish without the setup and maintenance cost
• Capacity that flexes with demand
• Coating data and traceability to pass to your customer
• Hazardous chemical waste and permits handled by the subcontractor

You also keep your team on your core work rather than managing a finishing line.

Aluminium components we anodise

We anodise aluminium extrusion, machined parts and fabrications, primarily in 6000 and 7000 grade aluminium. The finish suits parts for marine, automotive, architectural and engineering use, indoors and out.

Three anodising types cover most needs. Coating thicknesses follow BS ISO 7599.

Type	What it gives you	Typical thickness	Typical use
Sulphuric Anodising	Corrosion resistance, harder surface, decorative finish	5 to 25 micron	General-purpose parts, external applications
Hard Anodising	Thicker, tougher layer for wear and abrasion	25 to 50 micron	Sliding faces, machine parts, load-bearing components
Coloured	Colour with corrosion resistance, clear, black or red	Per finish spec	Architectural and decorative finishes

 

We measure coating thickness with XRF equipment during the process and at final inspection, and record it on every batch, so the oxide layer meets the spec your application needs. Grade suitability is worth checking at the design stage, since material composition affects the result. Send us the datasheet or a drawing and we’ll advise.

 

The long profile problem

Many anodising lines can’t take a full-length extrusion. The profile gets cut, finished in sections, then matched up later. That adds cost and leaves visible joins.

Our anodising tanks are 3m x 1.5m, and we anodise components up to 3m x 1m x 1m. So we finish long extrusions in one piece. No cutting, no sectioning, and consistent coating thickness along the whole length.

Because each length is anodised whole and measured at final inspection, colour stays consistent across that length rather than varying between sections finished at different times.

Fully integrated finishing

Anodising is one of several finishes we run under one roof. Parts move between processes without leaving site, which cuts handling, transport and the risk of transit damage.

Alongside anodising we offer:

• Masking for selective finishing.
• Vapour blasting and etching as surface preparation.
• Powder coating and wet spray painting.
• Laser engraving.

We operate to ISO 9001, with traceable processes from parts receipt to despatch and regular checks on anodising chemistry.

What to check before you commit

Use these to judge any subcontract anodiser:

• Standards – Work to BS ISO 7599, with ISO 9001 quality control.
• Coating thickness data – Proof the finish meets the micron spec you’ve set.
• Length capability – Long profiles finished whole, not in sections.
• Traceability – Records for your audit trail, receipt to despatch.
• Turnaround – Quoting and lead times that fit your programme.
• Logistics – Collection and delivery that protects parts in transit.

 

How we support extruders

We run anodising at our Measham site and keep work moving:

• Free collection and delivery, depending on location.
• Long extrusions anodised in one piece, up to 3m.
• 20+ years of anodising experience across the team.

Our Measham site sits in the Midlands, so transport stays short for Midlands extruders.

Test us with a sample

The simplest way to judge an anodiser is to send them a part. Send us a representative aluminium extrusion profile and we’ll anodise it free of charge, with coating thickness data included. (Subject to part size.)

Request a quote through the website or call the team on 01530 648 400 to discuss your requirements.