Sulphuric Acid Anodising | Machine Parts Finishing | Penta Precision

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Sulphuric Acid Anodising

Sulphuric Acid Anodising Process

As aluminium “oxidises” (the natural reaction between of air and aluminium) it produces a loose dry white powder, aluminium oxide. Sulphuric acid anodising is an electrolytic process using electricity (DC current) and a sulphuric acid electrolytic solution causing oxidation of the aluminium surface to form a thin “harder” film of aluminium oxide under controlled conditions.

The passing of the current liberates high volumes of Oxygen at the surface of the aluminium thus aiding controlled formation of the oxide layer. These processes do not produce a coating but are a conversion of the surface aluminium to aluminium oxide and are therefore metallurgically bonded.

The technique produces a tight but porous layer which, because it is porous, requires a sealing process to close the pores and prevent further natural attack on the aluminium.

Sealing is carried out by immersing the component in near boiling de-mineralised water, which if required can have small quantities of other chemicals, such as Nickel acetate or sodium dichromate to further enhance corrosion resistance.

The process is the most common protective treatment for aluminium. The anodised layer forms both within the surface substrate (penetration) as well as on top of the surface, growing the size of the component.

Before sealing, immersion in specially formulated dyes can be carried out, the open pores soak up the dye which will then be locked in by the sealing process, this can produce very attractive finishes but will depend on the thickness of the anodised film as the thinner the film, the less dye will be absorbed.

Why Choose Sulphuric Acid Anodising?

Similar or obsolete designations and standards


Components, Applications & Industries

Here are some examples of the industries and components for which sulphuric acid anodising is common and appropriate. This is by no means an exhaustive list. Please do get in touch if you want to talk through your project.

Typical Components & Applications:
Industry Examples:

Our Service

Penta Precision is able to offer Sulphuric Acid Anodising as part of our one stop machining service in the UK. As well as our own machining expertise, we are able to access our network of approved quality suppliers for the finishing of your parts, saving you the time and effort and helping to streamline your supply chain.

Can we make your supply chain
quicker and hassle-free?

Call our engineering team on
023 9266 8334
or contact us via our email form

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Tel: 023 9266 8334

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Penta Precision Engineering Ltd

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