Electrostatic Waterborne Coatings

Article From: Products Finishing,

Posted on: 10/1/1997

Switching to an electrostatic waterborne coating system can improve quality and reduce costs...

Moore Document Automation Systems, Dover, New Hampshire, a leading manufacturer of brand name and private label document processing systems, has a century-old reputation for dedication to product excellence, quality, reliability, durability and cost-efficiency. Moore was among the first in its field to be ISO 9001 certified. In addition, its equipment is UL listed, CSA certified and in full compliance with FCC and OSHA standards. Moore is also committed to the quality of its products. The company provides every customer with a 100 pct purchase satisfaction guarantee.

To maintain this tradition of quality and enhance the value of its product guarantee, Moore controls virtually every aspect of its manufacturing process, including the paint operation. However, a new OEM project recently strained the plant's paint line. As a result, Moore was forced to outsource more than 40 pct of its parts for painting.

Painting itself out of a corner. Tom Shufelt, Moore manufacturing engineer, said the project created an increased demand in production, which the company's paint operation simply could not handle.

"Although the increased volume requirements of the new project posed no problems for manufacturing," said Mr. Shufelt, "our finishing capabilities were immediately challenged. In response, we expanded our work day on the finishing line, running three shifts and using five workers per shift. We also attempted to speed up production on the paint line. But the limitations of our old paint system, due to overspray, inflexible existing automation and the considerable waste from trying to coat our special part configurations, just would not allow us to achieve the quantity and quality of finish we needed for our valued customers."

Moore's decade-old paint operation consisted of an automatic system with four vertically mounted bells in opposing automatic booths. The guns applied solvent-borne paint to a variety of steel and aluminum substrates featuring hundreds of different geometries. A 30-hp air compressor was also required to transport paint from 55-gal drums located in the paint kitchen to the paint booths some 95 ft away.

"Under the best conditions, we managed to coat about 90 pieces/hr, which was less than half of what scheduling required," said Mr. Shufelt. "Despite attempts to increase line speed, we still had problems with overspray, running paint, inconsistent film thickness, rework, rejects and increased VOC waste."

As a short-term solution, Moore began outsourcing nearly half of all its parts to area finishers. Meanwhile, executive management set a priority objective for its paint operation, eliminate quality control problems, resolve economic issues and bring all outsourced work back inside.

Making a choice. As a first step, Mr. Shufelt conducted a comparative study of powder, high-solids and waterborne materials. "We examined all aspects of the paint system," explained Mr. Shufelt, "from delivery methods to protection methods, including voltage-blocks and isolated canisters." The findings pointed to waterborne's ability to provide multi-color flexibility and maintain low VOCs.

Next, the company invited three leading paint system suppliers to study its operations firsthand and propose their best solution. Each one received a tour of Moore's facility, including open discussions with supervisors and operators about the paint line problems. Then, using identical parts and coating sample quantities from Eastern Chem-Lac, Malden, Massachusetts, each supplier conducted lab tests that Moore later reviewed and evaluated. The entire investigative process lasted 15 weeks.

"The lab tests really made our decision immediate and unanimous," stated Mr. Shufelt. "Nordson was the only company able to deliver what it promised and what we needed to meet or exceed our original objectives."

Dave Hagood, Nordson, Amherst, Ohio, liquid sales and design consultant, explained that the electrostatic waterborne technology Moore now uses, the Iso-Flo® voltage-block system and AN-9 automatic air-electrostatic spray guns, is designed to address and resolve a range of issues beyond increased capacity. "Moore needed technology that would accomplish a great deal," said Mr. Hagood. "From a quality standpoint, the system had to improve transfer efficiency, reduce rejects, deliver consistent film builds, provide more uniform, durable coating finishes and improve color-changing capability."

"With regard to economics, Moore wanted to increase material use and reduce overspray and labor costs related to reworks, cleanup and maintenance," Mr. Hagood stated. "Moore insisted on being well within compliance on all relevant state and federal regulations for VOCs, while maintaining the flexibility needed to finish hundreds of part configurations with many coating colors."

A documented success. The conversion from solvent-borne to waterborne coatings required less than one week, since most other elements of the paint operation, pre-wash, automatic and touch-up booths and ovens, stayed in place. "We added an encoder and a new light curtain and were open minded about making additional changes within our budget," said Mr. Shufelt. "But, with the waterborne system, it simply was not necessary."

"In fact," explained Mr. Shufelt, "while the footprint of our paint operation did not change, the total paint area was actually reduced by eliminating the paint kitchen." Switching from a remote to a local point-of-delivery system, Moore also reduced storage space and eliminated the need for an air compressor, saving $3,000/month on energy costs.

And while such savings were critical in justifying Moore's investment in the new paint system, the true measure of success was its ability to paint more parts, more efficiently, in less time, with better results.

"Our first order of business was to bring all outsourced finishing work back inside," said Tom Ritch, Moore vice president of operations. "This move required that we double our productivity without jeopardizing the high level of quality we expect from ourselves and our customers have come to expect from us. Working with electrostatic waterbornes has allowed us to achieve that and more. Now we can coat more than 200 parts/hr, running only two shifts. That's a 220 pct improvement in productivity."

First-pass coverage has significantly improved with the electrostatic waterborne system, with line speeds 30 pct faster and rack densities 25 pct higher. As a result of increased speeds and volumes, overall rack-to-unload times, which include touch-up and bake times, are 35 to 40 pct faster. In addition, reject rates are down from as high as 28 pct, to only four percent. "Considering the diverse geometries of our parts and the visible Faraday areas, these reductions are very dramatic," Mr. Shufelt stated.

"Despite the increased line speeds and higher film build, we are actually using less paint to achieve a more consistent, uniform coating thickness. Although our overall material use is about the same as before, we are now coating nearly three times as many parts as we were with the old bell system. Overspray and waste, and their related costs, are no longer problems needing solutions."

With Moore's operations always focused on excellent quality, all parts are inspected on a pass/fail basis. Film thickness and durability of the finish are key to the company's painting operation. "The finish must remain durable from the time parts come off the paint line, where they are stocked in bins, then trucked to a central facility for later assembly, until they have completed their useful lives in service. The electrostatic waterborne system allows us to achieve a desired mil thickness of 1.5 to 2.0. Previously, any mil thickness above 0.9 meant running paint, lots of rework and poor quality and efficiency."

Additional benefits. Replacement of solvent-borne materials with waterbornes has proven quite beneficial for Moore. Projected annual savings in hazardous waste disposal costs alone is $50,000. In addition, clean-up and maintenance labor costs have been cut dramatically, while color-change process time has dropped.

"With our old system, the bells had to be cleaned at least once every shift. Because each of the four bells had about 110 shaping-air orifices, they had to be cleaned with a dental pick. It was an extremely laborious, but essential, procedure," said Mr. Shufelt. "Now, we just flush with water and the system is clean. When a color change is scheduled, we simply switch hoses from one container to another. Color changes used to take 24 minutes, and now they are done in four."

Moore currently stocks a total of 14 colors, including five primary and nine secondary colors. Typically, between three to seven color changes are completed during each shift. With the new electrostatic waterborne system and its capability for faster, more efficient color changes, Moore can consider a wider variety of colors and more frequent color changes in the future.

The electrostatic waterborne system has not only eliminated waste, improved quality and efficiency and helped Moore realize significant savings, but continues to provide other benefits and possibilities.

"We now have a better sensing system and electromechanical controls that are much more precise. They allow us to quickly find the optimum setting for various parts, which is a real boost for overall operating efficiency," said Mr. Shufelt. "Paint line employees are pleased to work with technology that really works and is easy to use. Our technical field personnel point to the uniform coating and standardized gloss the system continually delivers. And our customers receive the best quality product available."

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