Content provided in partnership with

Automotive Industry

No more snap, crackle or pop: the Budd Company and AOC solve the 'paint pop' dilemma - Supply Side

Automotive Industries, Dec, 2002 by John Peter

Michael F. Dorney, vice president of sales and marketing for the Budd Co. will be the first to tell you the benefits of sheet molded compound (SMC).

It's his company that molds the Ford Explorer Sport Trac box side outer panels; the hood for the Ford Ranger; the hood, fender and deck lid for the Thunderbird and the front fenders for the Lincoln navigator.

The material, which is used to make everything from boat hulls to bathtubs, is a perfect application for automotive outer panels, he says. It's light-weight, dent resistant and corrosion proof. Intricate designs, like the T-bird's hood scoop, can be molded in one piece dies saving tooling costs and manufacturing time.

Most Popular Articles in Autos: Service Slants; 2007 utility vehicle buyer's guide: Side-By-Sides are popular; here's who ...; Transmission considerations: beyond the manual gearbox; Buell Motorcycle engineering, innovation, & dedication: in an industry ...; 100 + 10: America's oldest automotive magazine celebrates its 110th year ...; More »

"It's a perfect solution for low-volume niche vehicles," says Dorney, who points out as an example that a Mercury derivative can be done off of a Ford vehicle by changing the fenders, hood and front fascia with SMC. "The price per piece is cheaper than steel up to about 150,000 units."

Ford Motor Co. has been the leader in the use of SMC, beginning with the 2002 Explorer Sport Trac. But the automaker was experiencing a large number of paint defects on SMC parts. 'Paint pops' appeared along the edges of the panels and required repainting or, worst case scenario, scrapping the affected parts.

Ford approached both Budd and AOC, the resin supplier, in hopes that they could work together to find a solution to the problem.

"The root of the problem," says Dorney, "is that the OEM's want to assemble the entire body and run it once through the paint process. They expect SMC to perform like steel."

"Five years ago," says Michael Dettre, AOC business manager, "the thought was that the pops were being created by the resin gassing out through the paint as it went through the drying oven."

Dettre says that molders often used 'band-aids' to try and solve the problem. Some were spraying on an in-mold coating which doubled the cycle time and added complexity to the process because the mold had to be opened slightly before curing to apply the coating.

Others were spraying on sealers that were two-to-three times more expensive than standard automotive primers.

Budd went to all of their QE customers and collected defective panels. They catalogued more than 500 defects and noticed that most of them occurred on the edge of the panels. Paint pops were cross-sectioned and viewed under magnification. About 70 percent of the 'paint pops' were due to microcracks. Paint solvents were collecting in these microcracks and gassing out as the painted panels traveled through the drying oven. The majority of these microcracks occurred after the application of the primer coat while the part was being packaged and transported to the OEM.

The solution was to develop a stronger, tougher SMC formula. The first step was to develop a formula to measure the toughness of the SMC. The next step was to evaluate all of the components that made up the matrix and test different recipes until a tougher matrix was developed. The result was a new resin called Atryl TCA (Tough Class A) that was 69 percent stronger than the old resin. With Atryl TCA, Budd has seen a 95 percent reduction in pops in the lab, and initial manufacturing tests have yielded near zero defects on Explorer Sport Trac panels after paint.

Dorney says that 'paint pops' have been the biggest deterrent to the expanded use of SMC. Budd's products are now used in six Ford assembly plants and they are in the process of qualifying to other OEMs.

Automotive Industry

No more snap, crackle or pop: the Budd Company and AOC solve the 'paint pop' dilemma - Supply Side

Automotive Industries, Dec, 2002 by John Peter

Find Research Guides for:

Find Featured Titles for: Business

Most Popular Articles in Autos

Most Popular Publications in Autos