Powder coating has proven to be an excellent coating for a number of manufacturers in a variety of industries. Its utilization efficiency ranges from 90-99%, helping finishers reduce their material costs. The process is environmentally friendly, which is probably the most significant reason why the powder coating industry has continued to grow. And, powders provide a durable and tough finish that is pleasing to the eye of purchasers.
While powder coating does have its advantages, it does have some drawbacks as well. For years, one of the more noteworthy drawbacks was that it took a long, long time to change colors on a powder coating system, which restricted powder coating's advantages to those companies that coated the vast majority of their parts with one color.
Over the years, suppliers came up with ways to counteract the difficult and time-consuming color changes. Instead of recycling the powder, finishers could spray-to-waste. A spray-to-waste process allowed finishers to clean out the inside of the spray booth, attach a new feed box to a clean set of hoses and start spraying in a relatively short time. However, the increased transfer efficiency that made powder coating so attractive was lost with this solution.
Another resolution to the color change problem was to install multiple booths. One booth could be used for the color a finisher used more often while the second booth could be used for smaller run colors. This obviously increased the capital investment required for powder coating. And, who wants a piece of equipment sitting idle in his plant 70% of the time or more?
Recently, a new alternative has arrived on the scene to solve powder coating's color change problem-quick color change booths. While these systems have been used in Europe for some time, they are just beginning to hit the U.S. market. In fact, there are only a few finishers in the country that are currently using this technology.
Cybex International, Inc. (Medway, MA) is a manufacturer of high-quality fitness equipment that is sold to consumers and commercial gyms. The Medway plant manufactures the company's entire line of cardiovascular equipment, including treadmills and bikes. According to Bernie Murphy, manufacturing engineer at Cybex, "We make high-end products. We charge a higher price, but deliver a higher quality."
Originally Cybex liquid painted its parts, but when the company moved into a new facility it began sending parts out to a job shop to be coated. Because of the time involved shipping parts back and forth to the job shop everyday, the company decided to start coating its own parts again.
"We knew we wanted to go to powder coating because it was a superior product," stated Mr. Murphy. Plus, the company didn't want to have to deal with the waste treatment, which previously cost Cybex about $20,000 per year, that was required for a liquid painting system. "We really wanted to be more of a green company because of what we are-a fitness company. You don't make a health product and then cause health problems," explained Mr. Murphy.
Initially, Cybex began coating just the internal parts of the fitness equipment with only one color-black. This fit well with the company's just-in-time manufacturing philosophy, allowing it to powder coat parts a day before they would be needed on the assembly line. Gradually, the company began coating more and more parts in-house, and it even added some more colors.
When it started powder coating in more colors, Cybex quickly figured out the difficulties involved with color changes. "Color changes were taking 21/2 hours," said Mr. Murphy. "We had to switch over to a batch running style where we would run the black, because we were doing less of it, on Saturday."
During the week, Cybex would powder coat gray for the parts it would need the next day. When the employees came in Saturday they would go through the color change process. Then they would coat all of the black parts that would be needed in assembly for the next week. Finally, they would go through the color change process at the end of the day so that they could start spraying gray again Monday morning. "It was a logistics nightmare. You could never get fab to produce enough parts. We would always have to run black somewhere in the middle of the week. It killed our just-in-time philosophy," said Mr. Murphy.
Slow, Slow, Slow
The logistics nightmare was a result of the slow color change process. It took two workers about 21/2 hr to have the booth ready for the next color. Mr. Murphy's description of the color change process shows how time consuming and labor intensive the process was: "First, you would wipe down the entire booth to get as much powder out of it as possible. Then, you would blow out the inside of the booth. Of course, it was a stainless steel booth so the workers kept chasing themselves around trying to get the powder out.
"Next, the workers would climb underneath the booth and disconnect all of the venturi pumps. The pumps were all around the bottom of the fluid bed. That was probably the worst part. We had to have all of the hoses numbered because we had separate hose setups for the black and gray powders. We could just never get those clean. If we had to stop and clean each hose out and use the same hose, which was how we started out, it would probably add another hour.
"Once the hoses were disconnected, the workers would pull the color module out and get the next one ready to go in. The color module was so big that it took two workers to move it in. Then you would have to go underneath the booth again to reconnect everything. You had to make sure that the right hose went in the right place or you would have a major problem. Since we used the same guns for each color, we had to take the guns apart and clean them as well."
The length and complexity of the color change process caused several problems for Cybex. As was already mentioned, the color change process forced the company to abandon its just-in-time manufacturing philosophy. "If all the components weren't ready, then we would have to run some time during the week. Since we were so used to running just-in-time, it was nearly impossible to change the philosophy for just a few parts," explained Mr. Murphy.
The color change process also resulted in contamination problems, which were a result of the booth's construction and Cybex's difficulty in getting the powder kitchen and pumps completely clean each time a color was changed. "We've got a black wrinkle and a gray hammertone. It's just incredible what that stuff does to each other. The wrinkle can pretty much deal with anything, but the hammertone can't deal with the wrinkle, which was our main product. That really had an impact," declared Mr. Murphy.
The contamination issues lead to another problem-a decrease in employee morale. "With the old system we would let so many things go by," said Mr. Murphy. "Employees got used to the fact that they were going to get a certain level of quality. So, they just had to accept certain things or they wouldn't get any parts out. It wasn't anything the customer would notice, but we did."
Quick and Effortless
If you asked Mr. Murphy to describe the old color change process in a word, it would probably be terrible. Ask him the same question about the new color change system and he would probably say effortless.
Almost one year ago, Cybex installed the PVV EasyColorTM quick color changing powder booth from Sames Corp. Right from the start the company noticed a significant improvement in the color change process. The most significant change was in the speed of the process. Cybex can now change colors in about 15 min with just one person. The assembly and fabrication departments have become so accustomed to the quick color change times that they have the powder coating department changing colors three times a day or more.
The new quick color change booth also had a dramatic affect on Cybex's contamination problems and employee morale. Basically, the contamination problems have been eliminated. As a result, the employees have become very critical of their own work. Even the slightest imperfection results in a part being stripped and sent back through the powder line. Despite the empolyees' desire for perfect parts, the rework rate has gone from 25% to almost nothing.
The key to the success of this quick color change booth was making each part of it easy to clean. The booth is constructed of a PVC and honeycomb plastic composite. While Cybex's old stainless steel booth attracted lots of powder to the walls, the new plastic booth has very low powder buildup on the walls. The plastic is also easy to clean with an air wand. At Cybex, it is no longer necessary for workers to get inside the booth to wipe it down; the air wand takes care of everything.
Another significant feature of the powder booth that results in quick color change times is the air purge system. This system, which uses pulses of high pressure air, is used to clean the powder supply center, hoses, pumps and spray guns. Cleaning these areas is typically the most time consuming part of a color change. But, the air purge, with help from a slick liner on the inside of the hoses, is very quick and efficient.
Not only does the new booth facilitate a quick color change, but the process requires only one worker and is very simple. According to Mr. Murphy, anyone can learn the process in a day or two since it only involves pressing a few buttons on a computer screen, spraying out the inside of the booth with an air wand and installing a new powder box with the next color.
Cybex is one of only a few companies to have this technology in the U.S. And, the technology certainly has had a pronounced affect on the company's manufacturing process. Once the word gets out on how effective and efficient these quick color change systems are even those companies that have 20 or 30 colors will be powder coating their parts.