All BMW passenger cars receive a clear powder topcoat. Shown is a 3 Series Coupe.
Powder coating technology is in its fifth decade of commercial existence. The coatings panacea of the '70s and '80s has only scratched the surface of the OEM automotive coatings world. Why has there not been a more widespread use of this environmentally friendly technology?
It's true that powder has made huge inroads into the automotive components market. Under-hood parts and alloy wheels are good examples of applications where powder has advanced quickly and completely overtaken a market sector. This discussion, however, will focus on body coats - where they began, what technology is being used, who the players are, and what lies ahead.
The Chevy Colorado is powder coated at GM's Shreveport, La. plant.
The Pioneers
Powder has been evaluated as a body coat since its commercial debut in the 1960s. The Ford Motor Co.'s paint division in Mt Clemens, Mich., actually coated scores of Pintos in the early '70s with a single layer of acrylic-based powder. However, the cars quickly failed in the field due to corrosion problems. These failures were attributed to inadequate metal pretreatment and incomplete coverage of all metal surfaces. Soon thereafter, Ford discontinued its program to promote the use of powder coatings as body coats.Honda Motors in Japan applied a powder topcoat for a few years in the mid-'70s at its Sayama factory. This application won a prestigious Technology Award from the Japan Coating Technology Association in 1976. Eventually Honda moved toward waterborne technology and no longer uses powder as a body coat.
In 1980 General Motors sought powder technology for the S-10 truck plant it was constructing in Shreveport, La. The original plans were to use powder as both a primer surfacer and topcoat. Finishing lines for both applications were constructed and installed. The topcoat line consisted of 10 independent systems capable of applying separate topcoat colors, but the line was never commissioned. The company's primer surfacer line, however, became the first to commercially use powder as a body coat in North America. The Glidden Paint Co. developed and commercialized an epoxy polyester (hybrid) powder for this end-use.
No other powder body coats were commercialized in the ensuing 10 years.
Powder Regains its Sexiness
General Motors reinvigorated its interest in powder primer surfacers in the early 1990s when it made a commitment to install powder applications systems in two of its other light-duty truck plants (Linden, N.J. and Moraine, Ohio).Almost simultaneously, Chrysler made plans to systematically replace most of the liquid primer surfacer lines in its assembly plants with powder coating.
New players emerged as potential powder suppliers. Seibert Powder Coatings in Cleveland, Ohio was established. PPG had finally established a powder R&D effort in the mid 1980s and was now poised to support its traditional automotive customers with powder technology. And DuPont teamed up with the powder group at Glidden Paint to service the industry. The powder world finally found legitimacy in the automotive industry.
The Dodge Stratus is powder primed at the Sterling Heights, Mich. plant.
Technological Shifts
GM recognized the potential for topcoat delamination if underlying primer coats weren't UV durable. This led to the mandate to supply UV resistant powder primers. The powder suppliers responded by offering powder primer surfacers based on either polyurethane or acrylic resin technology. Chrysler thought otherwise and concentrated on ensuring that topcoats would not allow damaging UV energy to pass through to the primer. The company settled on using hybrid (epoxy polyester) powders as the platform for its primer surfacers. At the time of this writing, GM no longer uses acrylic technology for powder primer applications. Instead, it has introduced hybrid powder at a couple of its assembly plants.Color keyed powder primer technology is another interesting development. Automakers realized that some topcoats were much easier to apply over primers that were close in color to the topcoat. This solution remedied issues with coverage around difficult-to-coat areas. It provides a finished look for hard-to-paint areas such as inner surfaces of trunk and engine compartments, according to Rick Tansey, technical manager of PPG. This work was acknowledged with a 2006 PACE (Premier Automotive Suppliers' Contributions to Excellence) award for the collaborative effort between General Motors and PPG.
The Big Breakthrough
Arguably the most significant breakthrough in the history of powder coating technology arrived in 1998, when BMW commissioned its powder clear topcoat line in Dingolfing, Germany. This facility manufactures BMW's 5 and 7 series vehicles, which require some of the highest standards for appearance and durability in the industry. The supply contract was awarded to both Herberts Automotive Systems (Wuppertal, Germany) and PPG (Strongsville, Ohio). The coating technology is based on glycidyl methacrylate (GMA) acrylic technology.
Automotive Powder Today
Currently North American assembly plants lead in number and volume of powder used to coat automotive and light duty truck bodies. All applications involve the primer surfacer layer. Interestingly, two distinct powder technologies are employed (see Table 1, p. 18). Chrysler uses epoxy polyester-based powders, while General Motors uses both epoxy polyester and polyurethane technologies.In spite of the remarkable success with BMW's use of powder clear topcoats, Western Europe has lagged in the number of OEM installations using powder. Mercedes Benz has embraced a novel powder slurry technology developed at BASF to apply a clear topcoat to its "A" class cars in Rastatt, Germany.
It's interesting to note that a number of major automotive producers have avoided making any commitment to using powder as part of their coating strategy (see the "Conspicuously Absent" sidebar). Some do not have the regulatory pressure common in North America and Western Europe. Others have focused instead on using waterborne technology and/or emissions abatement techniques.
A passing review of EPA briefs shows that in spite of all Bill Ford's bluster about Ford being a "green" company, it has actively evaded any serious consideration for implementing the zero-VOC technology that powder brings.*
Another interesting situation is the lack of a level regulatory playing field for the foreign based automotive transplants in the U.S. It seems that most foreign automotive assembly plants not only bargained for attractive tax abatement and labor concessions when choosing a site, but they also were able to negotiate compromises on VOC emissions. Consequently, they are not forced to comply with the prevailing EPA strictures that the domestic automakers face. The Hyundai, Mercedes and Honda plants in America thus won't have to take a serious look at powder for the foreseeable future.
The Future
So where's all this going? The finishing system of an automotive assembly facility is the most expensive to build and operate of all the departments. The original drivers of environmental compliance and quality are still in place. However, the paradigm has shifted somewhat. Champ Bowden, the Global Automotive Market Manager for Akzo Nobel, says that future opportunities for OEM automotive powders may reside in new plants being built in the emerging economic centers in China, India, Southeast Asia and Eastern Europe. New plants will be smaller in size and will be more nimble to accommodate model changes.The coating process will have to be efficient and economical. Seibert's Automotive OEM Product Manager Roger Hulec states that the capital outlay needed to engineer a new finishing line will be closely scrutinized. Hence, the most efficient processes will receive the most attention. The ability to either combine (e.g., monobake two coats) or eliminate processing steps is a major emphasis in automotive coating R&D today.
Local supply and technical support will also be major considerations. Global players such as PPG, DuPont, Akzo and BASF will most probably consolidate the supply stream to the new and existing plants. The need to supply the entire coating package will also become a key driver. Coating producers will have to provide everything from the metal cleaning and pretreatment to the final topcoat.
How does powder fit into the future? Primer surfacers and clear topcoats certainly will be evaluated for use in new plants. The emphasis, though, will be on process consolidation and efficiency. One interesting development being pursued by a major automaker positions powder coating as not only the primer surfacer but also as the color coat. This concept will use an electrodeposition primer followed by a powder coating layer. The powder will act as a surfacer and also provide the topcoat color, while the final coat will be a durable clearcoat, probably using waterborne technology. Implementation of this system will effectively eliminate an entire process step, thus saving on capital, operating and material costs.
SIDEBAR: Conspicuously Absent
Major automotive producers that have avoided making any commitment to using powder as part of their coating strategy include:- Ford
- Toyota
- Honda
- Nissan
- Volkswagen
- Hyundai
- Fiat
- Renault
Some of these companies do not have the regulatory pressure common in North America and Western Europe. Others have focused instead on using waterborne technology and/or emissions abatement techniques.
SIDEBAR: The Powder Producers
There has been an evolution of supply in this market. Glidden was the first powder producer to supply primer surfacer in North America, but it is no longer in existence. The company's powder technology was absorbed by the Ferro Corp., which was eventually sold to Akzo Nobel. DuPont originally supplied powder primers developed and manufactured by Glidden and later by Ferro. Akzo continues to manufacture powder primer to satisfy DuPont's needs in North America. DuPont's acquisition of Herberts GmbH placed the company into a supply situation with BMW in Germany. The powder technology originally used at BMW was developed by Herberts' automotive group in Wuppertal, Germany.PPG got into the powder business in the mid to late 1980s and has come on strong with a virtual lock on the supply of powder primers to Chrysler. PPG's R&D efforts have spawned some innovative technology for clear topcoats.
Seibert Powder Coatings came out of nowhere to become a key powder supplier to General Motors. Siebert's technical innovation and comprehensive customer service allowed them to capture the majority of GM's powder primer business.
BASF has not made major in-roads into the North American powder primer market, mainly due to a lack of manufacturing capability in this region. Its approved primer technology had been toll-manufactured by a couple of different powder manufacturers until BASF built its own facility in Morganton, N.C. The company has, however, developed a unique powder slurry that is being successfully applied in Germany at a Mercedes Benz plant.
For information on reprints of this article, contact Jill DeVries atdevriesj@bnpmedia.com.
*See the EPA briefings concerning the permitting of Ford's Michigan Truck plant in 1998, online at www.ecocenter.org/Ford_MichiganTruck.pdf.
