In the mid-1990s,  Herman Miller  had no experience in powder coating MDF, but the company saw potential in the technology and decided to see if it could be used in the company's office furniture products.

Herman Miller began looking at powder coating MDF as an alternative to the laminate system then being used.

Rich Saddler, engineering manager, says that Herman Miller was looking for a new way of covering work surfaces with a monolithic, seamless process. The company sought a process that didn't require T-molding or high-pressure laminate, and would allow the use of compound curves and different shapes that weren't available with HPL.

"We wanted something that gave us more flexibility and freedom in designing our furniture," Saddler says. "All through the process, we used laminate as a benchmark. We had to be cost comparative to a traditional laminate-style surface."

Early commitment

"Herman Miller was looking ahead, finding different processes and products that are not the standard," Saddler says. "They are more futuristic, design-oriented, and they wanted to be the leader to the market in products and processes for the customer."

The powder coating effort was kept secret during its development.

Herman Miller contacted a number of board manufacturers and several powder suppliers to see how far each supplier had come in developing the process. They determined that the SierraPine board and Morton powder were the best available at that time, and were able to get these two companies to work with Herman Miller in developing the process and the product.

"The SierraPine Permacore MDF had the quality and high physical properties that were required to withstand the heat of the painting process," Saddler says. "With Morton, they were furthest along technologically in developing the formulation necessary to meet our performance requirements."

No other suppliers have met the requirements that Herman Miller has established.

Powder plant for lease

To start, Herman Miller needed a place to test materials, develop theories and a process for powder coating office furniture. The company didn't have to look far. An existing powder coating plant for steel products was found only 10 miles from Herman Miller's Zeeland, Mich., headquarters. The owner of this operation had closed it when a new plant was built, and had kept the equipment in place as a backup system.

Herman Miller leased the old line and renovated it with oven and conveyor improvements and a new stainless steel powder booth made by ITW Gema. In order to adapt the system to powder coating MDF instead of steel, the conveyor was modified to run in reverse: The unloading area was converted to the loading zone, and the cure oven was used as the preheat oven. The new powder coating booth was installed as close to the preheat oven as possible, and the dry-off oven was used as the cure oven. The washer was converted into a cooling tunnel because MDF parts hold heat much longer than steel or aluminum parts coated on powder coating lines.

Saddler says that theories of powder application and curing are similar for wood and metal products. But the concept of preconditioning a board, along with routing, sanding and preheating, is different from a steel line.

Herman Miller used the old plant as a laboratory, a prototype development line to test theories and what the process needed to be. They then took those specifications and developed a new paint system in a separate new plant.

"We were able to set up the process times and temperatures that were required to paint the MDF at the old line," Saddler says. "We set up different parameters for cooling times and heat-up times, as well as line speeds and part configuration."

Operating temperatures, line speeds and powder application settings were all tested on the old line. Conveyor speeds from 4 to 8 fpm and oven temperatures from 250 to 500 F were tested to determine the best settings for the system. A PLC system was installed in the new powder coating booth so parts could be sprayed automatically.

After months of research and testing, a process was developed that yielded consistent product quality. Sample parts in a variety of sizes and edge profiles were given to Herman Miller marketing. The Formcoat trade name was chosen for the process.

Resolve introduced

Meanwhile, a new office furniture line called  Resolve , introduced in 1999, was determined to be a good product for powder coating. This line is based on 120-degree angles that form a three-office pod. Work surfaces were shaped like an airplane's wings, providing more working room at arm's length. A waterfall profile routed on the edges of the work surfaces was designed to improve the ergonomics and appearance of the design.

Based on customer response and preliminary orders for Resolve at the 1999 NeoCon show, the decision was made to go ahead and build a new 115,000-square-foot plant on the north side of Holland.

Work began on the new building in the spring of 2000, and the coating system was installed by Rapid Engineering Inc. that summer. First-piece qualification, which certified the system was performing at the required level and was capable of producing parts for customers, was completed in November 2000, and the line began production the following month. Finishing was transferred from the old leased line to the new plant over several weeks.

The new powder coating plant uses an ITW Gema powder coating booth with a color-management system that feeds the powder coatings to the guns. Powder can be sprayed directly from the powder box, and other colors can be added with no additional capital required. Longer color runs mean greater efficiency in the finishing line.

Morton Powder Coatings supplied its Lamineer coating, which is a smooth coating in the low-gloss range that meets Herman Miller's marketing requirements. Colors can be changed in as little as six minutes, and material reclaim has been measured at more than 90 percent.

In general, work surfaces are the primary application for powder coating.

"We are working to expand our offerings into vertical applications, wall tiles, marker board surfaces and shelf end units," Saddler says. "Unusual shapes are where we excel, because any place a router can rout, we can paint. That's the benefit to it."

The only place that powder coating has not worked well so far is on certain parts that have deep details in the back side of the part, or where the back is routed out for steel reinforcement plates.

Manufacturing benefits

"Internally, this is a continuous flow process to rout the board, sand it and paint it, compared to the old way where you had to lay up laminate and then go to a router, rout the shape and bore the hole patterns, then go to T-molding," Saddler says. "It's a more continuous process, with fewer steps in the operation, and it allows you to paint the part completely."

This is a standalone plant, not connected to the main Herman Miller manufacturing plant.

"We supply the work surfaces and desk systems for the panel systems that are manufactured in other plants."

The new powder coating system has allowed Herman Miller to eliminate one of two shifts while greatly increasing capacity. Manufacturing costs have been cut by efficiencies gained by the system, and refinishing has been reduced about 8 percent.

Formcoat, Herman Miller's brand name for the technology, is being marketed as an alternative to high-pressure laminate, with similar performance properties. It is also said to have a more aesthetically pleasing, ergonomically friendly surface than the laminate.

Products initially picked as candidates for the Formcoat process included Howard tops for filing units, the Kiva product line and Ethospace keyboard trays.

Watching UV

Herman Miller has been watching the development of UV-cured powder coatings. "Our product is a 20 gloss with a smooth surface, kind of a butter smooth surface," Saddler says. "The UV market, in order to get that gloss range, is going to a microtexture, kind of a white sandpaper finish. That's not what our marketing department wants. So we have not been able to get a true comparison between the UV-cured and the convection-cured powder coating."

Saddler says the Formcoat plant is also investigating powder coating for third-party companies. "We have excess capacity," Saddler says. "We're looking for companies that are interested in providing a powder-coated MDF for their customers but don't want to invest in their own powder coating plant at this point in time."