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Futon maker plugs into electrostatic finishing system.

Sun Tui combines waterborne finishes with electrostatic spray equipment to stay one step ahead of clean air regulations while reducing finishing materials costs.

Like many wood products manufacturers these days, Sun Tui, a futon frame manufacturer based in St. Paul, Minn., has looked for ways to strike a balance between reducing emissions in its finishing department with maintaining product quality and an acceptable production rate.

Owner Dan Weiss said he thinks one answer lies in the finishing line that his company installed about a year ago. Sun Tui's system combines an automated electrostatic spray line with waterborne finishes. The initial results, though not 100 percent on the money 100 percent of the time, have nevertheless been far more encouraging than not and are getting better all the time, Weiss said.

Steve Bohnenstingle, who heads up the finishing program, said Sun Tui continues to learn more about mastering the system through on-the-job trial and error. "We're learning more every day," Bohnenstingle said. "You have to keep in mind that there are not very many wood-working shops using electrostatic. It's a whole new ballgame. But I am very confident that it will all work out."

In the beginning

How to best finish futon frames on a production basis was not even a consideration when Weiss began his business making upholstered futon cushions 10 years ago. He chose the name Sun Tui (pronounced Sun To), meaning the gentle and joyous from the I-Ching, a book of ancient Chinese wisdom. It is a fitting name considering the Far East origins of futon mattresses.

Weiss, who used to sell furniture at a retail store, said he decided to begin manufacturing futon cushions because he saw the potential for expanding the market, plus, "the quality of what was available was mixed."

"Futons are a portable, versatile form of bedding. You can roll it up against the wall or store it in a closet," Weiss said. "You can also put a futon on a frame so that it doubles as a couch and a fold-out bed."

Weiss spent his first five years in operation building up a customer base for futon cushions. "At the time, most of the frames my customers were buying were imported from the Far East," Weiss said. "I had one big catalog customer that wanted a one-stop source for cushions and frames."

Five years ago, Weiss obliged his customer's wish by opening up a separate plant about five minutes from the cushion factory to manufacture wood futon frames. Since then, the wood plant has expanded three times; Sun Tui's annual sales are about $8 million and growing. It's customer base includes Sears, Spiegel, Pier One and IKEA. Weiss plans to find a new location to bring the two halves of the business together under one roof.

Quality or bust

Weiss said one of his company's most recent breakthroughs was "hooking up" with Swedish-based furniture retail giant IKEA. "IKEA had gone to the Minnesota board of economic development looking for a manufacturer to produce some proprietary frames for them. The price had to be competitive with Europeans as well as other North American producers. And, of course, the quality had to be there, too.

"To maintain a long-term relationship with IKEA, a company must obtain ISO 9000 certification," Weiss said, referring to a voluntary quality assurance program instituted by the European-based International Standards Institute. "We're just beginning the application process. It's a lot of paperwork, but I think it will be well worth the effort."

IKEA's quality standards dovetail well with Weiss's own manufacturing philosophy. "I decided early on that if we're going to do it at all, we're going to do it right," Weiss said. "In some ways this business seems like an endless financial investment. We're constantly buying new equipment to improve ourselves. What we want to be is a good company for our customers, our employees and the environment."

For emphasis, Weiss pointed to a Timesavers widebelt sander on which all painted parts are pre-sanded to remove cross grain scratches prior to finishing. "I started the wood plant with a minimal investment. I spent more money on my new Timesavers sander than I spent on all of my original equipment combined."

A charged up system

Prior to installing the electrostatic system, Sun Tui used conventional air spray equipment with waterbased lacquers to finish its frames. The company manufactures some 24 frame styles, using mainly aspen, birch, oak, some basswood and pine for IKEA's frames.

"I decided from the start that we would use waterborne finishes because of my own value system and because I believe that this is the direction that the industry is headed," Weiss said. "Waterborne is more difficult to work with. We do get some grain raising but that has been minimized since switching to the electrostatic system."

The electrostatic system was put on line by Binks Manufacturing and consists of a conveyor line, a spray activation computer, a photo-sensitive light curtain, water spray guns, electrostatic bells, and a Sunkiss infrared oven. Bohnenstingle described the operation as follows:

1) Frame parts are manually hung on overhead conveyor hooks. The conveyor is grounded to the building so that it has a neutral charge. The hooks are wiped clean to prevent them from taking on a charge.

2) The conveyor moves the parts through a light curtain. As each frame passes through the light curtain, photo sensors gauge the frame's length and width. This information is communicated to the computer, which then knows when and for how long to activate the spray gun triggers and electrostatic bells.

3) A fine mist of water is sprayed on each side of the frame to make the surface more conductive. "The water is atomized so that it will not soak into the wood," Bohnenstingle said, adding, "The water has to be sprayed because wood at 6 to 8 percent moisture content is a poor conductor."

4) The frame then passes between two sets of electrostatic bells, diagonally positioned on either side of the frame. The bells put a negative charge on waterborne clear lacquer supplied by Sherwin-Williams. Acting like a magnet, the water-wet frames attract the negatively charged finish. The material not only coats the frame part facing the bells, it actually wraps around the edges.

5) The coated frame then enters the Sunkiss infrared oven that cures the finish at 140F to 150F.

6) The cured parts are sanded to remove any grain raising and the process is repeated a second time.

Bohnenstingle said, "The biggest trick has been getting a very even and consistent application of water. You get a heavier buildup of paint where there is more water. We're still doing more experimentation with the water applications. It's definitely getting better."

"We knew it wouldn't be easy," Weiss said. "There's a lot involved, such as getting the water guns and bells set up at the right angles and right spacing. We're still learning; we're still tweaking the system."

System benefits

One of the most obvious benefits of Sun Tui's finishing system is its environmental impact. Very little odor is detected from the system. The combination of greater transfer efficiency, meaning less overspray, and waterborne finishes adds up to reduced volatile organic compound emissions.

"We've increased our transfer efficiency by 30 to 35 percent over the conventional technology we replaced," Bohnenstingle said. "We've also made it easier to hang bigger parts to finish and are reducing reworking of parts. The quality has been exceptional. In the long run, we'll be way ahead."


Sun Tui employs a workcell philosophy for several of its machining operations.

For example, three operators are assigned to work as a team using three Vitap Alpha 27 boring machines purchased from Atlantic Machinery that are grouped together as a cell. Each of the 27-spindle Vitaps is set up differently to accomplish a specific boring pattern required for a given part.

"The first operator might take an arm piece and drill one or two sizes of holes so that hardware can be inserted to attach the arm to the frame," said Dan Wahlstrom, plant manager. "The first operator passes his drilled part to the second operator, whose responsibility may be to drill dowel holes to seat the arm top to the armrest frame. Operator two then hands the part to operator three, who drills additional hardware holes."

Because the three machines are the same model, they perform drilling at the same speed, Wahlstrom said. Thus, the production rate of the workcell is directly proportional to the speed of the slowest operator. "Because they are working together every day, a good work ethic develops and bonds them as a team. No one wants to be the person who is slowing everyone else up," he said, adding, "The output has been excellent and so has the quality because the machines really hold their tolerances."

Wahlstrom said that the drilling workcell can process a completed arm assembly at a rate of up to 200 parts per hour. When each of the three machines is used independently to drill less complicated workpieces, production can approach 600 parts per hour, he added.

Benefits of the workcell

Wahlstrom said the main advantages of grouping machines as cells is that there is less time spent staging parts for new setups and the workcells help save floor space.

Dan Weiss, Sun Tui president, rattled off two other benefits of the workcell concept. "First, it controls the material handling steps between machines. Second, quality control is better because each part is thoroughly inspected before going to the next cell. The next cell station is the customer of the previous cell. If they are not pleased with the quality of a part sent to them, they'll send it back to where it came from.

"The workcell concept interests me," Weiss added. "People seem to respond to it. For it to work, the cell must function as a team or it will function to the slowest worker's pace."
COPYRIGHT 1993 Vance Publishing Corp.
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Copyright 1993, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:includes related article
Author:Christianson, Rich
Publication:Wood & Wood Products
Date:Jan 1, 1993
Previous Article:Door maker quick delivers quality products.
Next Article:Turning wood waste into energy.

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