Autotex Steel polyester film looks like brushed stainless steel

It is a well-known fact that brushed stainless steel, though cosmetically pleasing and durable in terms of resistance to aggressive chemicals, staining and rusting, has a number of disadvantages too. These are particularly evident in day-to-day appliances, especially wherever stainless steel is used as a tactile interface. For example, even the most marginal brush with a finger will leave an unsightly mark on the steel surface. Of course this smear can be removed easily, but retaining the surface's pristine condition requires continuous cleaning. Furthermore, although steel is inherently robust, it is also delicate when it comes to surface damage, so even a modest amount of abrasion, such as that from a cleaning action, can permanently alter its surface. Once abraded, it is then difficult to return the surface to its original condition, especially if the product has already been put into use. Despite its perceived strength, stainless steel will also indent easily. This is often forgotten, as designers are attracted by the material's smooth appearance. While minor impact damage can be disguised, major dents will simply deform the material permanently and require the purchase of a new part.

Other well known disadvantages of stainless steel relate to its high initial manufacturing costs and the fact that it is a difficult material to weld, so it tends to be used more for relatively simple, fundamentally flat surfaces. Adding switches to a steel face requires drilling holes and designing a separate switching system to protrude through from underneath - which can allow the ingress of liquids through the front face unless suitable sealing is incorporated.

Advantages over stainless steel

Plastic materials and, in this instance PET films, can overcome many of these disadvantages, being formable, lighter, durable and versatile. But creating the pleasing cosmetic effects of brushed stainless steel on a plastic surface was something that had, until recently, eluded most manufacturers.

The development of a new hardcoated PET film, for use as a graphics overlay material in keyboards, fascias and instrument panels, looks set to change this situation.

Called Autotex Steel, this new material has an-ink receptive layer on the reverse surface and a specially developed hardcoated outer layer that is chemically bonded and UV cured. The hardcoat layer has a textured finish that, when printed on the reverse with standard metallic or newly developed mirror inks, creates the appearance of a brushed stainless steel panel.

The film is easy to handle and print, combining high levels of colour reproduction and definition with a tough outer surface that offers excellent resistance to abrasion, surface impact and a wide range of chemicals and solvents.

Integral switches

This innovative film also offers a number of advantages over conventional stainless steel materials. These range from the ability to produce high-quality keyboard or graphics panels at a far lower cost using standard screen processes, to easy embossing. Embossing makes Autotex Steel suitable for use with domed tactile membrane keypads or in applications where keys or panel areas need to have raised edges, as the material has an excellent flex modulus, with a typical life for domed keys in excess of five million actuations. In comparison, applying buttons to a steel surface would require separate components, thereby decreasing the number of potential applications and making the finished product more expensive. With Autotex Steel the operation is simple and the buttons are incorporated as one single part, making it easy to create a fully sealed fascia or keyboard panel impervious to liquid spills.

Unlike stainless steel, Autotex Steel does not show fingerprints, and can easily be printed to create clear display windows or contain secret-until-lit graphics, with the film offering excellent colour rendition and light transmission in clear areas. Graphics are normally reverse printed, so are protected from wear and abrasion by the body of the film substrate and the textured hardcoat top surface. This surface has also been formulated to resist a wide variety of common industrial solvents and cleaning fluids, including alcohols, ketones, weak acids and hydrocarbons.

Lastly, by manufacturing a part with Autotex Steel, overall weight can be reduced. This reduction in weight brings considerable savings not only during manufacturing, but also when shipping parts, particularly with the ever increasing transportation costs.

Autotex Steel comes in a number of gauges to make it suitable for a wide range of applications across virtually all markets. Such versatility, together with the inherent properties of PET films, offers product designers and screen printers an efficient and versatile method of developing striking and high-quality products with the cosmetic beauty of stainless steel, yet without any of its drawbacks.