By Michael Lauzon
CORRESPONDENT
Published: November 4, 2014 12:30 pm ET
Updated: November 4, 2014 12:38 pm ET
Image By: General Motors Co.
This 1984 Cadillac is a classic in more than styling. The model was the first application for a thermoplastic constant velocity joint.
ABC Group Inc. can celebrate its 40th anniversary with an award for one of its early breakthrough blow molding technologies.
The Toronto company won a Hall of Fame Award distinction from the Society of Plastics Engineers’ automotive division for plastic chassis components made by blow molding thermoplastic elastomer. The parts, debuted on some General Motors Co. vehicles, first emerged from ABC Group laboratories in 1984.
The parts’ name is a mouthful, almost as difficult to pronounce as the parts are to be molded. Constant velocity joint half-shaft drive-axle boot seals protect and lubricate under-chassis components in a very unfriendly environment of grease, salt, freezing water, mud and stones. They began to replace injection molded rubber boots on the bases of performance and cost.
SPE rightly spreads credit to ABC Group’s key partners, DuPont Co. and General Motor Co.’s former Saginaw Steering Gear Division. DuPont supplied Hytrel thermoplastic copolyester elastomer for the application while the GM division supplied the know-how to adapt the blow molding technology to the automaker’s vehicles. The partners’ work began in 1977 with joint development of the first blow-molded TPE rack and pinion steering boot, itself a breakthrough for the time.
The new CVJ boots were “a far more robust CVJ sealing solution that also was lighter, more durable and less costly than the injection-molded rubber boots it replaced,” SPE noted in announcing the award. Early adopters were Buick Riviera, Cadillac Eldorado and the Oldsmobile Toronado sedans. Now, some 85 percent of front-axle CVJ boot seals on light-duty vehicles worldwide use TPE in this application to replace polychloroprene rubber. (DuPont also was a major producer of this type of rubber under the tradename Neoprene.)
SPE’s auto division Hall of Fame awards are based on several criteria. Parts must be made of plastics or composites, they must have 15 years of continuous service in the market and preferably have been widely accepted within the automotive and transportation industries.
“It was a truly bold and revolutionary change to switch from thermoset rubber to thermoplastic elastomer,” stated David Reed, SPE Hall of Fame committee chair and retired GM employee, who also was involved in GM’s approval process. “Saginaw ran every performance test we could come up with on the new material, and with each iteration, the TPE passed with flying colors. It offered us both low-temperature flex to -40° F [40° C] and high-temperature durability to 250° F [121° C].”
Image By: ABC Group
The constant velocity joint boot developed by ABC Group went into production in 1984 and now is used globally.
CVJ boots protect bearings in the constant-velocity joint by keeping out road-borne contaminants. And they keep lubricating grease inside the CVJ as the drive axle rotates and propels the vehicle. These demands were hard on rubber boots and a cause of most drive-axle repairs.
ABC Group and its partners, encouraged by the success of TPE rack and pinion boots, developed specialized equipment to blow mold the CVJ products. DuPont came up with customized TPEs for the application. ABC Group established a compounding operation, Saflex, partly to handle demand for the TPE materials.
The main challenge was to maintain tight tolerances required at the large and small sealing surfaces, plus wall thickness control, ABC said in an email correspondence. It developed a sizing technology for both the large and small diameters. This maintained tight tolerances while helping consistent wall thickness control.
Parison control, material distribution for thinner-walled parts, shot-to-shot consistency and ramp-up were big challenges the partners had to overcome. ABC Group patented process developments allowing tighter tolerances on the sealing surface to prevent leaks, “a big issue with the era’s incumbent technology.”
The limited initial launch saw only 250,000 parts under the cars. In the next year, 1985, ABC Group blow molded 11 million of the boots for GM. Initial tooling savings amounted to $380,000. A boot’s weight at 64 grams was less than half the standard boot. Now TPE boots weighing only 40 grams are in use.
ABC Group still is one of the largest molders for the product.
Its technology reduced scrap compared to processes using thermoset rubber. ABC regrinds flash from the process and blends it with virgin TPE to mold more CVJ boots.
“This product was ABC Group’s first innovation, and it allowed the company to significantly increase its sales and expand beyond the North American market,” noted ABC Group senior vice president Danny Cacciacarro in a news release. “The unique process we developed allowed us to create features on the inside of the part and achieve new levels of dimensional control for sealing surfaces.”
With its technical expertise proven, ABC Group expanded globally. One of its first forays overseas was a joint venture with a Japanese auto parts molder, a real achievement given Japanese firms’ propensity to rely on their own technology and an aversion to partner with North American players. Now ABC Group blow molds boots in Canada, Mexico, Brazil, Spain and China. Rear axles today also use TPE boots.
SPE will hand out the Hall of Fame award in Livonia, Mich., on Nov. 12. The society claims its innovation awards program is the oldest and largest competition of its kind and that dozens of teams participate by submitting nominations. About 700 automotive industry plastics engineers and executives attend the gala.
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