News Release

Hard Anodising adds versatility to aluminium

18th May 2004

 
Colin John, managing director of surface coating specialist Poeton Industries suggests that considering coating technology early in the production engineering cycle can save time, money and disappointment when working with aluminium.

The latest developments in the surface coating of aluminium have the potential to lower manufacturing costs, improve product performance and appearance, and control quality - provided manufacturing companies talk to coating specialist in the early stages of development.

An understanding of the design requirements for example, will help specialist surface engineering companies such as Poeton decide on the most suitable coating from the vast range available, including nickel and nickel composites, hard chrome, hard anodising, thermal spraying and the latest composite and Keronite coatings.

Poeton customers also have access to the fully equipped Advanced Plating Technology Centre at Gloucester, a recent investment that has created a coating centre of excellence within the Poeton Group.

Among the analytical and test equipment now in place are PC-driven microscopes capable of resolving surfaces and micro-sections down to sub-micron levels, with attachments that allow entry into bores only 2mm in diameter! This investigative capability is supported by state-of-the-art chemical analysis, including Atomic Absorption.
Importantly, the new centre boasts an array of wear and friction test equipment, and environmental corrosion chambers that have enabled ground-breaking developments in such diverse applications as F1 engines, plastic moulding and stylish eye-wear. Our R&D team is also able to successfully resolve problems such as in-service component failure, by providing analysis that has saved customers from potentially expensive litigation.

This wealth of experience can be applied to aluminium to solve problems such as how to increase product life, improve performance and reliability, enhance appearance and reduce product and production costs. It can even extend to expert witness support and product failure analysis for compensation claims.

By choosing the optimum coating technology manufacturers can also eliminate most of aluminium's disadvantages - such as its susceptibility to unsightly pitting corrosion and inherent softness - enabling aluminium to be used for a greater range of functions.

For example Poeton's unique Apticote coatings consistently achieve up to 1500vpn (Vickers Pyramid Number) hardness on selected aluminium alloys, often combined with properties such as high lubricity, low friction, and wear and corrosion resistance.

With new coating technologies to harden its surface and expand its use into ever widening engineering markets, production of refined aluminium is rising fast - up 5% in 2002.
Perhaps the most popular coating for aluminium is anodising, where parts are oxidised by an electrolytic process, producing a hard aluminium oxide coating that grows out of the parent metal. Techniques vary but generally, anodising carried out at 0ºC results in a much harder and thicker (450Hv, 60µ) coating that provides greatly improved wear and corrosion resistance.
The latest composite anodising processes make good use of the fine columnar structure that is a major feature of the anodising process, reducing friction and increasing aluminium's ability to withstand environments such as salt or high humidity. This provides wider scope for designers and extends service life for end users.
Anticipating growth from the widening of applications for aluminium, Poeton has invested in a new, world class, state-of-the-art hard anodising line for its Apticote 300 aluminium coating process. The high-capacity line offers 24 hours a day, seven days a week operation with a standard of consistency that has previously been impossible to achieve. It also enables us to provide a fast response on a wide range of high quality, low-cost, hard anodising options.

All the latest advances in process technology have been designed into the plant, including energy-efficient refrigerated cooling and an innovative heat-surge control system featuring 5000 litre 'cold box' heat exchangers. A smart processor also controls and logs every detail of every batch to provide critical quality control data, ensuring that once customer requirements have been agreed, repeatable quality is guaranteed.

The line is also fully integrated with the process control and R&D laboratories in the Technology Centre to ensure that customers receive fast order turn-round, excellent quality and superior product performance from the Apticote 300 hard anodising process.

The handling of parts is critical to the anodising process and distinguishes the best coating companies from the rest!
On the new line, components are loaded onto a 'flight bar' transporter system that runs over the top of the tanks. Operators simply press a button and the transporter moves down the line placing components into a series of tanks for washing, pre-treatment, etc., before they reach one of the two large anodising tanks. The line delivers a ten-fold increase in capacity that enables us to service at reasonable cost, customers who want quality hard anodising and composite coatings on high volume components.

By automating the Apticote 300 and 350 processes we have brought real innovation to the anodising market. Included in the range of coatings that can be processed are composite coatings that make aluminium surfaces as hard as steel by combining the hardness of aluminium oxide with the low friction, wear resistance and corrosion protection of flourocarbon polymers.

Typical applications for hard anodising include aerospace and automotive components, pharmaceutical and food processing equipment, packaging machinery, and the offshore oil and electronics industries.

Advice on engineering applications, which includes the selection of the optimum coating for aluminium alloys such as HE30 (6082), L65 (2014), L160 (7075), DTD 735 AND LM 25, is available from Poeton experts or on our comprehensive website at www.poeton.co.uk. The site also features ISIS, Poeton's own unique coating selection software.

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File: Aluminium Today article