Because non-metal substrates by definition tend to be poor heat conductors, powder coating them has been a challenge. According to Mike Chapman, president at Vulcan Catalytic Systems, one of the secrets to the success of Vulcan’s powder coating cure ovens lies in
the design and placement of the company’s catalytic heaters relative to the position of the powder spray booths.

Vulcan was formed 18 years ago to develop the uses of catalytic heaters in the plastics industry,
according to Chapman. He says, “The main market for this technology as it turned out was in the thermoforming end of the plastics business as opposed to curing thermoset resins.” He explains that in thermoforming, thermoplastic sheets are heated with infrared (IR) for about 3 minutes and then vacuum-formed into molds, cooled and released. “Today the bulk of the spa/hot tub producers as well as many custom formers heat their plastic with gas catalytic systems supplied by Vulcan, the driving force being energy savings over electric IR heating costs,” Chapman says.

Chapman says that thermoforming is one of the most demanding industry segments for control of the IR heating process, as it is basically a heat-sensitive substrate, starting Redline Garagegear uses powder coated medium density MDF board for doors, drawer fronts and panels because of its strength and smooth, uniform surface. to get soft at 250°F with a forming temperature of 375°F. He says the sheet must be heated evenly across the entire area, with the heat penetrated into the core as much as possible to give a material distribution during the vacuum process. Cold spots cause thick areas and hot spots cause thin areas—heating large sheets 8 ft x 10 ft for a spa tub with deep draws requires repeatable controlled temperature distribution.

“With this knowledge and control equipment that was developed for the plastics industry,” Chapman explains, “curing powder coatings on heat-sensitive substrates put Vulcan on a fast track to supplying successful MDF powder coating production lines.

In 2002, Vulcan supplied heaters and controls to Acre Products, a UK-based company producing TV Stands for the major TV brands, Chapman says. Realizing the strong potential for powder on MDF, Vulcan formed MDF Powder Coat Systems and installed an in-house system with three ovens and two powder booths to demonstrate the technology and run production for local companies that required a tough, attractive finish on the MDF parts that they were routing on CNC machines. “Additionally, this facility became the testing ground for a number of powder coat manufactures that could also see the potential growth in the MDF market,” Chapman says.

“Over the next 4 years, nine lines have been installed stretching between New Zealand, Europe and the United States,” Chapman says. The largest company using the technology is in California and operates at 18 fpm, producing roughly 300 kitchen cabinet doors per hour. The smallest line produces up to 100 parts a day, with multiple color changes for maximum flexibility for a cost that is similar to a CNC machine. “This latter system is a grassroots system that is not unlike the early days of powder on metal where powder is applied with hand guns and the whole system needs to be cost effective,” Chapman says.

He goes on to say that preaching about how secure the process is to potential investors has been an uphill battle. “There is a legacy of confusion that persists, slowing these investors from pulling the trigger,” Chapman says. The problem stems from the failed early days of powder coating MDF using long dwell times of the MDF board in convection ovens for preheating the board and curing the powder.

“This prolonged heating time damaged the board, by virtually removing all the moisture in the board, altering its physical properties and dimensions. Additionally, this process was a high consumer of energy, with expensive capital investment and at the end of the day produced low quality products and had very narrow window of production parameters to successfully get the powder on the MDF and cured satisfactorily,” Chapman adds.

In February 2007, one of the last convection-style MDF coating systems was scrapped in favor of a ...

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