Anodising: Metal Surface Treatment Services

Amfin provide Anodise services, a protective and decorative surface treatment for multiple aerospace primes and other industries around the world.

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What is anodising?

Anodising is an electrolytic passivation process that increases the thickness of the natural oxide layer on the surface of metal parts.

Many metals, such as aluminium, naturally have a protective oxide film. This film forms very quickly in air and protects the metal against corrosion, but it is very thin. The anodising process is used to increase the thickness of the natural oxide film for corrosion protection or increased wear abrasion, improving the performance of the component and extending service life.

Anodising is done on a wide variety of parts from landing gear struts to mountaineering clips and from cladding panels to picture frames.

This process protects the surface of the metal from damage caused by abrasion. The metal will have improved resistance to rust and other causes of wear and tear. The porous surface of the metal can then be coloured with dyes, without the peeling and flaking that could occur with organic paint.



The anodising process explained

In the process of anodising, the metal part is immersed in an acid electrolyte bath and an electrical current is passed  through it. A cathode is placed inside the anodising tank, with the metal acting as the anode. This causes oxygen ions to form and combine with the atoms on the surface of the metal being anodised. This allows a metal oxide film to grow on the surface of the metal being treated.

Conditions during the process, such as acidity, temperature and current are carefully controlled to allow a consistent oxide layer to be formed at the desired thickness and strength.

Before a metal can be anodised it needs to undergo all necessary pre-treatments, which will influence the final anodised coating. The pre-treatments can be chemical surface treatments such as paint stripping and pickling, or mechanical processes such as abrasive blasting. At Amfin, we can handle a range of pre-treatments, contact us to get a quote´╗┐.

The quality, or thickness will depend on the type and temperature of the electrolyte solution being used.

After a metal has been anodised, the surface of the metal is very porous and easily attracts other materials. At this stage dyes can be added to the metals, and the colour of the metal skin can be changed. Once coloured the pores in the metal are sealed, by dipping the metal into a de-ionised bath.

The main reasons why a part is anodised

  • Improved resistance to corrosion and weathering
  • To increase hardness and improve wear resistance
  • As a base for paint or dry film lubricants
  • To improve adhesive bond strength
  • Aesthetic reasons
  • To create an electrically insulating surface

AMFIN offers various different anodising processes including;

  • Sulphuric Anodise
  • Tartaric Sulphuric Anodise
  • Chromic Anodise
  • Hard Anodise

After anodising components may require sealing. This further improves the components resistance to corrosion. Amfins sealing options are;

  • Hot water seal
  • Potassium Dichromate seal
  • Sodium Dichromate seal
  • Nickel acetate seal.

For further more info get in touch or contact us to get a quote

Our anodising processes & services

Materials Amfin Can ProcessTank Dimensions (mm)
Nickel Based Alloys
Magnesium Alloys
Aluminium Alloys
Titanium Alloys
Low Alloy Steels
Copper based alloys
Corrosion Resistant Steels


Chromic Anodise

Sulphuric Anodise

Hard Anodising

Tartaric Sulphuric Anodise


What are the different types of anodising?

At Amfin we offer different types of anodising to suit specific manufacturing requirements. The anodising process can increase corrosion resistance, wear resistance, and provide a better adhesion for paint and glue.

Sulphuric Acid Anodising

Sulphuric anodising is highly durable and provides high corrosion resistance. The process causes the oxide to form both inside and outside the metal, which leaves a clear finish that can accept a coloured dye. Sulphuric acid anodising can be used for a range of general engineering, or decorative applications, as well as in the defence and aerospace industries.

Hard Anodising

Hard anodising is a form of sulphuric anodising, where the process is intensified to produce significantly thicker, denser, more durable finish. A hard anodised metal part will feature a much darker decorative finish making it unsuitable for colouring. The wear resistance of a hard anodised metal such as aluminium can be comparable to that of steel and offer a lightweight solution at a lower price.

Chromic Acid Anodising

Chromic anodising produces a thin oxide film which have good corrosion resistance but due to the thickness are not suitable for dyeing. As the chromic anodised film is so thin, it does not affect precision tolerances that are used in the aerospace and defence industries.

Tartaric Sulphuric Acid Anodising

Tartaric Sulphuric Anodising (TSA) is commonly used in aerospace and defence applications and provides high corrosion resistance and excellent paint bonding properties. Tartaric sulphuric anodising is more a more environmentally friendly process, making it a good alternative to chromic anodising.

Get an anodising quote

Contact us today for a free quote and find out how Amfin can assist at every stage of production.

  • Over 40 finishing operations all in 1 facility enabling us to maximise efficiency, reduce costs and minimise lead times.
  • Established suite of accreditations to finish, test and inspect a wide range of components from many areas of precision manufacturing.
  • Trusted by manufacturers in Aerospace, Defence, Rail and Automotive industries.
  • Experienced, dedicated team with over 75 years' experience working in the industry, providing bespoke services and products to 1st tier engineering companies.

Anodising FAQ

Advantages of anodising

The main benefit of anodised metals is that it is highly durable and wear resistant, therefore reducing ongoing maintenance costs.

Anodic coatings are particularly useful to use in high-traffic areas where the metal will be subject to physical abuse and abrasive cleaners. The coatings are integrated with the underlying metal, which prevents the coating from chipping or peeling.

Anodised surfaces do tend to pick up dirt and stains more easily, but the surface is very easy to clean. Using a mild soap for routine maintenance will make the surface look as good as new.

What metals can be anodised?

Aluminium alloys are the most common metals to be anodised. Amfin can anodise aluminium, titanium, and magnesium alloys.

How long does the anodised finish last?

Anodised coatings are a highly durable, weather resistant finish that protects the base metal. The lifetime of the finish will depend on the thickness or density of the coating, as well as the quality of the seal.

If you have any further questions on anodising, contact us on:
+44 (0) 1455 637284
Or email:
[email protected]