Finish more than 3,000 aluminum parts in 10 to 20 colors during a single shift

In the highly visible world of premium windows and doors, architects, builders and property owners often have special needs and high expectations. Windows and doors must have resistance to a variety of environmental conditions.

Once installed, the windows and doors are subjected to decades of extreme weathering, from direct sunlight to salty ocean air to cold mountain winds. Plus, the doors must withstand temperatures that range from 20-100° F.

Through all of this, the finished product must continue to look great. More and more, the marketplace wants special features that set their homes or buildings apart from the rest. They turn to customized shapes, sizes and colors that create a distinctive look.

To keep up with growing market demands, one of the Midwest’s largest window and door manufacturers, managed to meet delivery schedules by outsourcing the painting of its aluminum windows and doors to designated job shops. While the finish quality, consistency and durability from the paint shops were excellent, outsourcing lead times became so extended that they were beginning to result in lost work.

To do this the company installed a fully auto[1]mated, in-house paint line to finish all its aluminum parts, including cladding, screen channels and accessories.

The new paint operation was designed to be completely self-sufficient, and the 30,000-sq-ft facility was equipped to meet very specific objectives. This particular company manufactures more than 100 aluminum window and door profiles that range in size from 0.1875 inches wide to 14 ft long. Most orders involve relatively small custom jobs, 20 to 30 windows in specific shapes and designer colors, and are run on a “per order” basis.

“We needed to finish between 3,000 to 4,000 parts per day with the flexibility to apply two to 20 colors during a single shift,” explains a company representative, “In short, we needed a paint system that could accommodate a multitude of part profiles, handle frequent color changes, match colors consistently and continuously, provide a quality finish and minimize paint waste and touchup.”

Control is a key feature, since every order requires a fairly unique racking pattern. For example, it’s not unusual to see a single half-circle window frame hung on a rack. The controls will minimize any waste. The precise control of the spray gun triggering not only minimizes paint waste, it also reduces cleanup costs and helps control VOC emissions.

Another important part of the automated system are the spray guns. Based on the finish quality achieved by the job shops previously used, the company’s engineers knew that they wanted to use rotary atomizers in the new paint system. “We investigated Nordson RA-20 rotary atomizers and were immediately sold on the finish quality, minimal paint overspray and consistency from piece[1]to piece and rack to rack,” says the company’s facility manager.

The rotary atomizers apply paint between 0.8 and 1.2 mil (dry) and are checked routinely to minimize the need for touchup. A manual spray booth is positioned immediately after the automated booths to reinforce coverage in unusual circumstances such as double-hung parts with extreme configurations and recesses. The company currently uses an average of 110 gallons of paint per day (shift) to coat 2,500 to 3,000 parts.

Rotary atomizer technology allows very low paint utilization. The ability to achieve close-in painting gives high transfer efficiency and good penetration. Likewise, spray pattern control of the rotary atomizers helps reduce overspray and paint waste.

The rotary atomizers are positioned only 5 inches from the parts. This is possible because the RA-20 doesn’t have a minimum sparking distance. “The automated paint line has given us tremendous flexibility,” the facility manager explains. “We can now handle 10 to 12 different color changes and produce 3,000 finished parts every day. By eliminating the need to outsource, we’ve dramatically reduced our lead time on custom colors. Best of all, we’ve achieved all this and are only running at about a third of our capacity.”