PPG's breakthrough powder coating
PPG's breakthrough powder coating
Keywords Automotive industry, Powder coatings, PPG
A breakthrough in automotive paint technology is said to be responsible for the gleaming finishes of autos rolling off the BMW production line in Germany. The coating is stated to be environmentally benign, speeds production and improves finish quality.
The final finish on 5- and 7-Series models produced at the Dingolfing assembly plant is an Enviracryl coating stated to be the world's first powder clear coat developed by Pittsburgh-based PPG Industries.
Powder coatings were introduced in the auto industry during the 1980s, initially on components such as wheels and engine blocks; body primer applications began later.
But clear coat is a colorless finish applied to protect the auto's color coating. According to PPG,unlike conventional liquid coatings, its powder product is solvent-free, can be recycled and requires no chemicals for treating waste created during the spray process.
"Powder clear coat offers many advantages", says Ronald J. Isger, global manager of automotive powder technology at PPG's Strongsville, Ohio, coatings facility. "BMW acknowledges that our Enviracryl powder clear coat is a premium product appropriate for its premium cars."
"There is a huge potential with powder", said Walter Wimmer, manager of BMW's paint shop. "That is why we decided to go ahead with construction of powder clear coat lines at Dingolfing."
Isger adds that PPG is working with the Low Emission Paint Consortium, created by Chrysler Corp., Ford Motor Co. and General Motors Corp., which is evaluating the environmental benefits of powder clear coats for North American automakers.
Powder clear coats exceed requirements of United States Environmental Protection Agency regulations and represent the most environment-compatible coatings technology available,according to Isger. Because over-spray can be recovered and reused, creating little or no waste, powder clear coats give automakers a cost-effective alternative to liquid clear coats, he adds, with no volatile organic compounds(VOCs) from application.
With solvent-based liquid clear coats, air circulated through the paint booth cannot be recycled back into the booth and requires an emission control system. Powder coatings require much less booth ventilation and permit up to 90 percent of the air volume to be recirculated. Because the powder application process is cleaner, booth maintenance is minimal and use of aggressive cleaning compounds is unnecessary.
Powder clear coat is spray-applied electrostatically to grounded car bodies. Isger says powder particles remain in an excited state within the electrical field, contributing to a consistent coating thickness free of drips, runs or sags that can occur with liquids, so rejection rates for finish quality are low. A combination of infrared and convection ovens melt the powder particles adhering to the car body, fusing them.
"Because of increasingly stringent environmental requirements, powder coatings are the fastest growing segment of the coatings industry", says Isger. "These products are environmentally friendly, but our goal for top coats, especially important to automotive customers, is to also match the finish quality of liquid coatings and exceed them in appearance and durability."
Further details are available from PPG Industries Inc. Tel: +1 412 434 2445.
