News Release

Surface Coating Technology

April 2002

 
A spokesman for surface coating specialist Poeton Industries suggests that considering the technology much earlier in the production engineering cycle can save time and money and disappointment.

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

Tapping in to the experience of specialist surface engineering companies in the early stages of manufacturing means involving them in materials and coating selection, component design and process and production. An understanding of the design requirements will help them decide on the most suitable coating. Poeton have a range of eighty or more coatings that include nickel and nickel composites, hard chrome, hard anodising, thermal spraying and a unique range of Apticote composite coatings.

For example, specifying a specialised nickel composite coating that combines the protection of low friction polymers with the natural hardness and corrosion resistance of nickel, can provide excellent hardness, permanent lubricity and superior wear abrasion and chemical resistance when applied to components manufactured from stainless steel and other ferrous alloys.

The same coating can also substantially reduce material costs by allowing low cost materials to be specified to meet high performance needs.

Parts manufactured from low carbon steel and coated with the nickel composite can be used to replace more expensive alloy components with no loss of performance. Costs are further reduced as parts can be machined from more workable and readily available metals.

Coatings can be applied to a wide range of base materials and complex shapes and are suitable for many applications, including those requiring USDA and FDA compliance.

Nickel Composite coatings can also achieve four times the wear resistance of electroless nickel, outperforming hard chrome in dry running applications and operating at temperatures from -115ºC to +260ºC.

If design engineers carry out Kaizen improvement reviews with Poeton surface engineers before designs are finalised many thousands of pounds can be saved. Poeton offers advice via their website (www.poeton.co.uk) where ISIS, the UK's first coating selection software, can be used. Alternatively, we run seminars or one-to-one consultations using friction and wear data from over 400 surface coating tests.

Whilst an approach in the early stages is certainly the ideal situation, many coatings are applied to solve problems that only become apparent after production.

An impressive example of post-production problem solving is a non-stick coating that has quadrupled the life of aluminium plate sets used in a high-volume, food packaging machine. The new machine wraps and seals products three times faster than before using a plate and knife mechanism that combines pressure and temperature to create an effective seal.

The plates are made from aluminium to provide maximum heat transfer and were originally coated with a high grade, non-stick polymer, applied directly to the base material.

However, progressive failures were experienced after just three months due to the polymer separating from the plates' aluminium substrate. This resulted in loss of sealing efficiency on the packaging and costly disposal and replacement of the sub-standard product.

At this stage a coating with a special bonding structure was applied to the plate sets. It overcame the problem and extended the life expectancy of the sets to at least 12 months - four times that of the previous non-stick polymer.
The manufacturer says the machine's functional performance is now measurable and predictable, enabling a planned and efficient schedule of replacement.
This application demonstrates that, at a time when it is possible to specify non-stick polymers of every conceivable colour and composition, the real problems remain. How to ensure that the coating sticks to the component substrate. And then how to stop it spreading and extruding under high contact loads.

It is worth remembering that, whilst many coatings are non-stick they are also soft and suffer wear and damage in an unacceptably short time. And even with the correct degree of non-stick and sufficient endurance, if the coating does not adhere properly to the substrate it is possible for products passing through the machine to separate the coating from the component.

In this instance the new coating solved these problems using a uniquely graded interface at the component substrate that prevented disbonding.

Another recent innovation is the use of 'Keronite' in coatings such as Poeton's Apticote 3000M. This allows magnesium alloys to be used for the first time in 'functioning' applications such as high-performance engine pistons, sliding bearings, valve trains, fuel pumps, spindles, pneumatic drives and hydraulic systems.

It's 350 to 600 Hv hardness range makes it ideal for applications where reduced weight is crucial. It can increase the wear of WE 54 alloys and stiffen ultra thin alloy sections and fabrications. And its ability to withstand voltages in excess of 1000v DC makes it an ideal surface for electrical and electronic components.

Other advantages include a friction coefficient of less than 0.15, excellent corrosion and heat resistance and abrasion resistance ten times better than steel. Adhesive wear resistance is the equivalent of case hardened steel.

With so much innovation available, manufacturers should take the time to ask for technical advice and discuss sample part processing. It can save money, time and a considerable amount of stress!

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