Using an eye-catching finish has become an increasingly used method to differentiate products from the competition and excite the consumer’s interest. For OEMs using prefinished metals for either cabinets or trim pieces, the options for achieving a new look have also grown. While the idea of using prefinished metals isn’t new, there are new opportunities to exploit them. Those opportunities arise from the introduction of new materials and changing consumer tastes. Today’s consumers are more amenable to colorful designs, but they also have practical concerns, such as fingerprint resistance and finish durability.

Using a prefinished metal eliminates a messy production bottleneck for OEMs and reduces some of their environmental compliance issues, but it also increases their choices. Metals can be prefinished in a number of different ways, including the application of liquid or powder coatings; the application of films; surface alteration by use of chemical conversion processes; and the use of various metallic deposition processes, such as electroplating. All combined, these methods provide OEMs with an unprecedented array of choices for both appearance and texture.

These new looks for decorative metal are matched by an improved robustness of both the substrate and surface materials over it, allowing the prefinished metals to be used in a wider range of fabrication methods than in the past. Many of today’s prefinished metals can be formed or joined in ways not possible before because of concern for damaging the finish.

A range of colors and finishes of Sandvik’s Decorex prdouct line.

Several companies have recently released new decorative metal products such as: Clad-Rex of Franklin Park, Ill.; Corus UK Limited, London; ThyssenKrupp of Duisburg, Germany; and Sandvik Materials Technology of Sandviken, Sweden.

Clad-Rex, makers of vinyl-laminated metals such as those used on refrigerators and freezers, now offers a multitude of new looks, says George Liebrock, manager of sales and marketing for Clad-Rex. The vinyl products give designers the opportunity to use a rainbow of colors, many different finishes and three-dimensional textures, and combine them to achieve even greater combinations.

Liebrock has been in the industry for more than 30 years. He was part of the team that help GE convert their in-house paint operations to purchasing prepainted metal. Converting to prepainted metals took some work, he says, in that the OEMs had to change material handling practices so the finish didn’t get damaged during manufacturing and assembly operation. Tooling and dies often had to be changed. Assembly procedures had to be rethought as products could no longer be weld assembled as the process would burn the paint. Instead, they would have to use mechanical fastening, adhesive bonding or other types of joining techniques.

Sandvik offers 12 colors and four finishes in its Decorex line and additional versions are under development.

Manufacturers who currently buy prepainted material, and are interested in using vinyl-laminated metals will not have to go through such an ordeal, Liebrock says. Because the industry is already using prepainted and precoated materials, switching to vinyl – a precoated product – allows them to use their skill sets; they already know how to handle, form, cut and assemble these types of materials. Some tooling and dies may need to be adjusted because vinyl is 6-mils to 8-mils thick, as compared to paint, which is 1-mil thick.

This might be a small price to pay for the available choices as Liebrock says that there are hundreds of combinations of looks that can be achieved with vinyl. “Vinyl not only has color, but it also has texture and patterns and can add flair to a design,” he says.

For example, many appliances today feature a metallic look. That design can be achieved with metallic-look vinyls giving the appearance of platinum, pewter, brass, stainless steel, and more. Vinyls are also available in granite patterns, or wood grains, and can be used to match the look of kitchen cabinetry or counter tops. “If you have a wood grain such as a light maple or cherry, you can use a platinum product, that introduces a beige effect, which softens the look of the appliance. But, it still looks like an appliance.”

A close-up of ThyssenKrupp’s Metal Look product.

The vinyl is also very durable, he says. It can undergo shearing, trimming and cutoff, bending, drawing, roll forming and other processes. It is resistant to chemicals and abrasions. For instance, in chemical resistance testing, the vinyl laminate was subjected to 17 days of exposure to a variety of solutions including 10 percent sulfuric acid, 10 percent nitric acid, and others, and there was no noticeable effect. It did, however, swell slightly when subjected to 10 percent formaldehyde and had a slight shrink when it was exposed to ethanol. It has been heat tested, in which the material was exposed to 150 DegF for 600 hours and showed no loss of adhesion or tendency toward delamination. Similarly, it was exposed for 1,000 hours to an environment with 100 percent relative humidity at 150 DegF, and it showed no evidence of adhesion failure or blistering.

The material can come with a protective strippable sheet and can be ordered in coil form or in precoated blanks. The material, which is most often applied to steel and aluminum, can be purchased laminated on both sides depending on the application. Clad-Rex also offers a metal-to-metal laminate, where two pieces of steel enclose a core material such as foam or other insulating materials. Vinyl-laminated products, with its extra thickness,  naturally offer sound damping and sound insulation properties and the metal-to-metal laminate product offers even greater sound deadening and insulation properties, Liebrock says.

He adds that these sound-damping properties, as well as the low cost and durability of vinyl are just a few reasons for designers to choose it. One example of a new application is a walk-in cooler like those found at a convenience store. In the past, these units were often in the back of the store because they were not attractive and they could be loud, especially when the condensing motor cycled on. Vinyl-coated panels solved both these problems, Liebrock says. “It made it quieter and with vinyl, the front panels could be made to match the store’s design or make the units more attractive.”

A range of possible variations that can be achieved using ThyssenKrupp’s PladurM.

Liebrock says that the variety of decorative finishes now available allows appliance manufacturers a chance to better satisfy their customers in a world market. Many countries, especially many Asian countries, have embraced colors and patterns. “U.S. manufacturers can’t live in a cocoon,” he says. “They have to think like a world supplier and because of the wide use of vinyl through the Asian and European market, they should explore more vinyl coated products and provide more decorative finishes.”

If manufacturers do move toward more diverse appliance fronts, other suppliers, whether offering vinyl or another decorative prefinished metal, are ready to offer them. For example, Sandvik is expanding the range of colors and finishes available for its Decorex stainless steel materials.

Sandvik has targeted Decorex as an alternative for applications where anodized aluminum is used. Traditionally, manufacturers used aluminum because of its lower cost and its formability resulting from it being a soft metal. But, because aluminum is not as hard, strong or durable as stainless steel, it is often put through an anodizing process that strengthens it, and makes it more corrosion and abrasion resistant. The anodizing process also is used to achieve the required color.

The glass-effect look of Corus’ new Motiva GS high gloss product, which comes in a variety of colors.

It is these extra anodizing steps that negate any initial cost advantage anodized aluminum may have over stainless steel, says Andrew Keirns, a Sandvik product specialist based in California. For example, Sandvik did a cost analysis of stainless steel vs. anodized aluminum material for use on a USB flash drive. The initial cost of the stainless steel was much higher, he says, but after analyzing the anodizing production steps needed to get the required color, the actual per piece cost using stainless steel was about 20 percent less than with anodized aluminum.

In addition, stainless steel has a number of other advantages, says Christina Berardi, marketing and sales manager for Sandvik. She says that stainless steel is stronger than aluminum and less material is needed to meet stiffness and yield strength specifications. Stainless steel also provides more corrosion and abrasion resistance than does even anodized aluminum, she says.

Berardi says that the Decorex material is very formable and can undergo a variety of fabrication processes such as stamping, deep drawing, punching and marking. The strips can be welded, laser cut, etched or engraved. The fabrication and finishing processes can be accomplished without any oil or lubricant, which helps eliminate cleaning steps, she says.

Berardi adds that Sandvik’s close control of production processes have resulted in color tolerances that keep the color consistent and helps ensure adhesion between the base material and the color coating. This makes it possible for Decorex to be cold formed and bent to a close radii without hurting color quality. “The color, no matter how the material is bent, will stick and not flake off,” she says. Adhesion was tested in accordance with the “Cross-cut test to ISO 2409:1992.”

The coloring of Decorex is based on a roll-to-roll process that enables a wide range of coating materials to be applied to stainless steel strip at high speeds. The technique also allows for single-sided as well as double-sided coatings. Coating thicknesses can range from a few nanometers to a few micrometers and the coatings can consist of aluminum (AI), nickel (Ni), copper (Cu) or silver (Ag) and mixtures of elements or binary compounds such as A1203 or Ti02.

Delivered in coiled strips, Decorex comes in 12 different colors including amber, olive, sapphire, hazel, pacific, tangerine, granite, lavender, mocha, ebony, coral, and emerald. It comes in four finishes including dull, satin, hairline and bright. Berardi says that the company is coming up with new textures and colors that will be introduced soon.

Decorex is available in thicknesses from 0.1 mm up to 0.8 mm and in strip widths of up to 370 mm. Eventually, the material will be available in widths up to 800 mm. The base material comes in stainless steel material grades of AISI 304 in annealed condition and AISI 301 in cold-rolled condition. Other stainless steel alloys are available on request.

According to Berardi, the finishes are fingerprint resistant; smudges can be wiped away even on a bright finish material. The surface finishes are also scratch resistant and meet pencil hardness tests as outlined in ISO 15184:1984 Paints and Varnishes and D3363-00 Standard Test Method for Film Hardness by Pencil Test. It has a 150HV rating and tensile strength of 650 +/-100 MPa. Its corrosion resistance is derived from the base material such as AISI 430, 301 or 304.  Properties include magnetism and conductivity and other capabilities can be achieved through changes in the base material or with additional coatings.

While stainless steel upfront costs is higher than that of other materials, Berardi says that the final cost for the OEMs is lower than aluminum because of improved production flow, higher yields, shorter process times, and less environmental issues. “Stainless steel is our know-how,” she says, “We can coat on any material, but we focus on stainless steel because it has so many advantages such as corrosion and abrasion resistance, stiffness and environmental benefits.”

When specifying materials, performance and cost are often trade-offs. For company’s looking for a stainless steel appearance, but without the upfront costs, ThyssenKrupp of Duisburg, Germany, offers a new product called PladurM that comes in a number of metallic looks, including stainless steel. In fact, the M stands for Metal Look, according to Axel Pohl, project manager with the Profit Center Color of ThyssenKrupp Steel AG. The company offers a family of Pladur products that can be used in a variety of hot, cold and wet applications. What is new with this product, Pohl says, is the vast array of colors and finishes that are now available.

The material was developed in conjunction with a home appliance manufacturer of stoves. Its uses have expanded, as have the manufacturers who use PladurM. The material is now being used by BSH Bosch und Siemens in its refrigerators and stoves, and by other manufacturers who manufacture such products as computer cases and stereo components.

PladurM is a hot-dip finished, galvanized steel. It is a thin-sheet product that is covered with a metalized decorative film that is applied by coil application. The metalized film gives the steel the appearance of high-price materials such as aluminum, copper, stainless steel and titanium. “It is a carbon steel product and the charm of it is that you can imitate and emulate the look of much more expensive materials,” Pohl says.

Available in coils and cut lengths, the new product comes in a variety of metallic looks, brushed and non-brushed surfaces and dyed, translucent variants, Pohl says. It comes in different levels of shine including glossy, matte and brushed finishes. Standard options are bright steel finish, titanium finish and aluminum finish, but custom designs are possible depending on the size of the order.

The product can be used in fabrication operations such as deep drawing, folding, roll forming, punching and stamping. Testing of the material has shown good results, says Pohl. For instance, the material undergoes a T-Bend test, a formability test in which the panel is impacted and must show no hairline cracking (≤ 2.5 T), and the Erichsen-cupping test, a ductility test to measure sheet metal quality (> 6mm).

Pohl says the material is finger print resistant, as well as durable against various chemicals and abrasions. In chemical resistance tests, the material was exposed to 10 percent acetic acid, 10 percent citric acid, shoe polish, mustard, vegetable oil, insect repellent spray, chloride cleanser, onion, butter, black current juice, Coca Cola and red wine. The material also underwent a surface hardness test measuring (sensitiveness against marking Erichsen stick  318 ≥ 2.5 N) as well as corrosion resistance tests (under creepage ≤ 2 mm / >72 h; blistering on surface m0g0 / >72 h). After the test, the surface showed no visible damage.

The type of testing that ThyssenKrupp subjects its products is typical of the industry. The Corus Group UK Ltd., London, a maker of prefinished metals, is no exception. Before releasing its newest product, the Motiva GS, the material was subjected to extensive  testing, including salt spray and humidity testing, pencil hardness, and abrasion testing, testing for stain resistance and more.

The company’s Motiva GS is a high-gloss, glass-effect product that has been formulated to create a unique finish together with excellent scratch, mar and corrosion resistance, says Mark Owens, Consumer Products Project Manager for Corus.

The standard gloss level of Motiva GS is 100 percent, at a 60 Deg line of sight angle, but custom gloss levels are available depending on customer requirements and the end-use application. The Motiva GS range is currently available in four colors, including Strong Red, Strong Blue, Weak Green and Bronze. The Motiva family of products is specifically formulated for appliances and can be used for wrap-arounds, tops, doors and side panels on clothes washers, refrigerators, dishwashers, tumble dryers, and many others.

Owens says that the Motiva GS comes as a co-laminate finish, while other Motiva products are available in paint, laminate and co-laminate finishes. The co-laminated steel is a pre-finished strip steel product with a number of adhesive paint layers and treatments and a PET film bonded topcoat that is applied to the top surface and a number of paint layers and treatments applied to the bottom surface.

The pre-finished strip steel product features a number of paint layers and treatments applied to both top and bottom surfaces. The laminated steel is a pre-finished strip steel product with treatment and adhesive paint layers and a polymer film topcoat applied to the top surface. The polymer film may be single or multi-layered. A paint layer and treatment may be applied to the bottom surface.

Owens says that a range of substrates can be used including aluminum alloys, stainless steel, cold rolled steel, hot dipped galvanized steel, and Galvatite, a Corus hot-dip galvanized steel product that is available with either a pure zinc coating or an iron-zinc alloy coating. The choice of substrate depends on the application, but the most often used substrate is CR and hot-dipped galvanized.

Some of the production techniques that the material can undergo include shearing, blanking, press braking, bending and folding, roll forming and deep drawing and spinning without affecting the surface finish. The extent to how far it can be fabricated depends on the grade of steel used for the substrate. The grade of steel selected dictates what can and cannot be achieved in terms of the formability. An area with a deeper drawing requirement such as a clothes washer door would need a softer grade of steel than a basic wrap-around.

The new products from Corus, Clad-Rex, Sandvik and ThyssenKrupp, represent just a sampling of the ever-expanding range of prefinished metal products available to appliance manufacturers. As research and development continues in this area, OEMs will have even more ways to design unique and eye-catching appliances.

For more information, enter:
Clad-Rex Inc email: gliebrock@cladrex.com
Corus Group email: Mark.T.Owens@corusgroup.com
Sandvik Materials Technology email: christina.berardi@sandvik.com
ThyssenKrupp Steel email: bernd.overmaat@thyssenkrupp.com