Powder coating on MDF has changed a lot in the few years it has been available to the secondary woodworking industry. New techniques being used to powder coat MDF are only making the process more and more attractive to store fixture manufacturers like Warren, R.I.-based Display World, which specializes in point-of-purchase displays.

Cliff Ferreira, who works in engineering and cost management at Display World, says the company outsources powder coating of its MDF store fixture parts because of the durability of the powder coated MDF. "It's a much more durable product," he says. "A lot of displays get handled by people, so it's the alternative to paint, without question."

Display World manufactures the MDF parts to customer specifications and then sends the product to nearby MDF Powder Coat Systems in Portsmouth, R.I.

Michael Chapman, owner and president of MDF Powder Coat Systems, explains that he got into the business of powder coating MDF parts because his other company, Vulcan Catalytic Systems, developed a new method for curing powder coating on MDF. The only way to sell the newly developed oven concept was to set the system up, start demonstrating to potential investors and start producing powder coated MDF parts for local customers.

"We put a full 300-foot line in here with all the oven technology installed on that line. Because we had that, we started doing work for local point-of-purchase manufacturing within a 100-mile radius of here even as far as Pittsburgh," Chapman says.

When asked about his MDF Powder Coat Systems customer base, Chapman says, "It's mostly the store fixture business. The kitchen cabinets have some interest, but mostly it's store fixturing, shelving, anything to do with point of purchase."

The process

The technique developed by Chapman's companies has improved the structural integrity of MDF powder coated products, he says.

In the catalytic heating process, MDF is preheated in a catalytic infrared oven for one-and-a-half to two minutes so the board surface temperature reaches 200 F for a short time. As the board leaves the oven, it absorbs the heat, reducing the board surface temperature to 120 to 140 F. The water content of the board, which is typically 5 to 8 percent, becomes energized and the board starts to act as a conductor. Once the board is grounded, it will attract the negatively charged particles of powder that are sprayed toward the board.

For curing the powder on the board, the Vulcan process uses a four-and-a-half minute cure time in a 40-zone catalytic infrared oven.

This differs from an older, more commonly known process, says Chapman. In the first stage of this process, MDF parts spend to 15 to 20 minutes preheating in a convection oven. The board temperature reaches 300 F or more. This temperature reaches the core of the board and drives moisture from the board, which is removed from the surface of the board by the high-velocity hot air.

Once the moisture content has been reduced, the board is not a conductor, says Chapman. With this process, the board is so hot, that the powder fuses onto the board as it comes in contact with the hot surface.

Chapman says that the excessive temperature alters not only the physical properties of the board (reduced internal bond strength) but also reduces the board thickness and induces internal and edge cracking within the board. With this older process, the boards are cured for 10 to 15 minutes in a convection oven.

Applications

Flexcel, a unit division of Kimball International, has decided to install the curing technology developed by Chapman's MDF Powder Coat Systems and plans to begin powder coating MDF parts for its customers in June 2005.

With more than 3,500 employees and 15 locations worldwide, flexcel is a contract manufacturer that serves the office furniture, hospitality, residential, retail infrastructure and entertainment industries, says Chris Thyen, director of technology at flexcel.

Thyen says flexcel shines when it comes to finishing. "Our core competency is finish. It's what we do better than anyone else. That's not just wood finish, it's also painted product, powder coated metal products and soon powder coated MDF."

When flexcel begins to offer powder coated MDF product to its customers, Thyen says he expects to garner the most attention from the retail infrastructure, or store fixture customers, and the entertainment market, which includes TV stands, TV cabinets and entertainment centers. "We think those are the two initial customer bases we'll satisfy."

According to Thyen, flexcel looked at a number of oven manufacturers and chose Vulcan because of its use of gas catalytic infrared ovens. "There are some advantages to the infrared technology," he says. "We are really trying to minimize the amount of heat that penetrates the core of the panel so the structural integrity of that panel is not jeopardized."

Alternatives, benefits

Powder coated MDF is being billed to store fixture manufacturers as an alternative to paint; and it is being suggested as an alternative to thermofoil.

According to Chapman, the main advantage of powder coat on MDF is its cost. He says powder coated MDF runs $1 to $2 per square foot, not including the MDF. Meanwhile, thermofoiling MDF costs $3 to $6 per square foot, not including the MDF.

Powder coating MDF is also more environmentally friendly because it uses 98 percent of the powder. Powder that doesn't attach to MDF can be reclaimed and reused. Thermofoiling MDF produces a lot of waste, says Chapman, because much of the thermofoil is cut from the board and thrown away.

Advice from users

Thyen of flexcel says he's excited about his company's implementation of the MDF powder coating technology, but he also sees a few advantages when it comes to thermofoil. "The thermoform process may have applications in some areas like a high-use work surface. The use of powder and thermoform is greatly dependent on the specific application and performance expectations.

"Where the design intent is very critical or where the joints or edges are important to the concept, powder on MDF is much better than the thermoform. I think vertical surfaces are great applications. A low-impact work surface is a great application," says Thyen.

Ferreira of Display World offers practical advice to store fixture manufacturers who are considering the use of powder coat on their MDF product: "On the edge grain of the MDF, you really have to sand the edge and make sure it's smooth and you end up getting a really good coverage with powder coat. And you get a better product if those sharp edges are rounded over."

 

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