Switching From Liquid Spray Coating To Powder Coating

In early 1993, the American affiliate of the world's largest enclosure manufacturer decided to switch from a liquid spray coating to a powder coating system. The results were dramatic. "As a company, we're extremely satisfied," said Bud Rehl, manager of plant services for RITTAL Corp. USA. "We've improved quality and reliability while reducing costs, and we've virtually eliminated air emissions from our top-coating processes."

RITTAL makes an impressive array of electrical and electronic enclosures and accessories. The worldwide corporation, headquartered in Herborn, Germany, produces more than 4,000 products, including junction boxes, computer enclosures, electrical enclosures, bus bar systems and network cabinets. The customer list includes automotive, telecommunications and computer giants as well as small- and medium-sized firms. In the U.S., RITTAL employs more than 400 people, most of whom work in the central production facility in Springfield, OH, which began operation in 1989. In 1996, the company sold some 2 million pieces worldwide.

Until the early '90s, RITTAL used high-solids liquid coatings in two standard colors as well as a variety of special colors on its array of products. Parts were hung on carriers that were sent through a 2,000-ft, PIC-controlled power-and-free conveyor system made up of six process routes. Parts scheduled for one of the company's standard colors passed through the finishing system's automated liquid booth where six applicators on 108-inch vertical stroke reciprocators applied the liquid paint. "We did color changes in that area too," explained Mr. Rehl. The special liquid colors were produced using an in-house blend system and applied by hand at a separate hand-spray booth. Coated parts then went through a curing oven and on to the unload area of the system.

In late 1992, RITTAL decided to make a change. "Two things drove the change to powder coating," stated Mr. Rehl. "First, our parent company in Germany decided to pursue powder coating on a worldwide basis for its durability, chip resistance and all other favorable physical aspects. Second, our company philosophy is to protect and improve the environment, both from an air emissions perspective and in the interests of better waste management. Powder coating is an excellent way to do that."

Working with industry specifications and specifications from the parent corporation in Germany, Mr. Rehl developed the detailed requirements for the coatings RITTAL's Ohio plant would use. "My objective was to find a powder coating producer that could supply coating for our three levels of usage: high, which included our two main standard colors, beige texture and orange smooth; intermediate, including our other standard colors, such as white and other shades of gray that are not used as widely as the main ones; and low, our special colors." He started by looking closely at seven companies and finally settled on a supplier that is only a 45-min drive from the plant. As Mr. Rehl also noted, "They can deliver new formula, special, low-volume colors to us in 10 working days. Repeat orders for these special colors usually take less than a week."

At the same time, Mr. Rehl began looking for an equipment supplier, focusing on three companies. "The big drivers in that decision were the best available technology and the work envelope size," Mr. Rehl said. RITTAL wanted to be able to powder coat all of the plant's products.

The transition from liquid to powder went smoothly, moving from decision to implementation in less than 6 months. In July 1993, RITTAL installed the first automated powder coating booth in its U.S. facility. The application system uses 12 guns on reciprocators and 2 manual guns, one on each side of the booth. Four rollaway collectors attached to fluidizing units facilitate color change. "We started out with four collectors overall, so we could change colors," Mr. Rehl explained. "Two of the collectors were for our standard beige color. The other two held a smooth orange."

With custom colors still in demand, RITTAL also made a major modification in the automatic booth it had previously used for liquid coating, turning it into a second powder coating booth. That booth now uses several box feed units to hand-apply special color powder coatings. After converting the automatic booth, RITTAL dismantled its one remaining liquid coating booth, which had been used for the hand application of liquid special colors. This cleared the way for the company's complete transition to powder coating technology.

Relying on a single automated booth did have a drawback, changing colors was a time consuming process, even with rollaway collectors. "It took about 3-6 man hours," Mr. Rehl stated. By the mid-90s, RITTAL's volume was high enough and the powder coating was performing so well that the company decided to add a second automated booth. The second booth was purchased, installed and in use in May 1996. By loading each booth with one of the two standard colors, the plant can now apply standard colors to parts without having to interrupt production to switch collectors. The booth modifications and additions along with some conveyor path/logic changes have resulted in an increase in capacity of more than 40%. Mr. Rehl noted that its recent expansion would take the company well into the future. No major expansion of its powder coating facilities are planned, although Mr. Rehl believes the next logical step is to modify the hand application booth sometime in the future.

What is certain is that the change to powder coating continues to be very good for RITTAL's bottom line. "We're realizing significant cost savings, as we anticipated, in materials use, maintenance costs, waste disposal and energy use," proclaimed Mr. Rehl.