Port Huron, Mich. - After four years of use in thousands of vehicles, an automotive water pump impeller made from an engineering thermoplastic continues to outperform its predecessor made from a combination of aluminum and steel, according to the molder. Used in the cooling system of a Chrysler 3.5L engine, it is one of the few plastic impellers used in North American vehicles, according to Chrysler Corporation.

Development of the plastic part, which replaced an aluminum casting, began in 1989 when Huron Plastics Group (HPG) discovered it could eliminate impeller corrosion problems.

The strong, precisely molded vanes are just part of the benefits Ryton^® PPS brings to this automobile water pump impeller injection molded by Huron Plastics Group for companies such as Chrysler Corp.

"The part also significantly boosted the pump's efficiency," explained Jaime Klomhaus, engineering director at HPG. The same amount of water is pumped, but less power is needed because of tighter dimensional control and less part weight."

Familiarity with PPS played a part in HPG's selection of the resin to mold the part. "Participation from Chevron Phillips Chemical in our advanced quality planning (AQP) team added a comfort level as well," explained Klomhaus.

To injection-mold the part, HPG is using a 40 percent glass-filled compound of Ryton^® polyphenylene sulfide (PPS) from Chevron Phillips Chemical.

A 150-ton Engel injection molding machine with a vision system is used to mold the impellers. Before each cycle, inserts are manually placed in the mold. A 'master' image of properly installed inserts is compared to the image presented for the current machine cycle by the system's vision unit. Any variance will prevent the mold from closing, alerting machine operators to correct the problem.

HPG - READY FOR ACTION
The Powertrain Systems division of HPG uses 27 Engel and Battenfeld machines plus six Battenfeld two-shot molding machines. Founded in 1963 as a molder of close-tolerance nylon and acetal parts, HPG now concentrates on molding automotive parts.

This division specializing in metal replacement can process a number of materials including nylon 6/6, nylon 4/6, polyphthalamide (PPA), polyester and PPS.

Taking a team approach to running its business has brought HPG great success. Since the development of its AQP team in 1991, which consists of representatives from numerous disciplines throughout HPG, the company has seen an average annual growth rate of 20 percent.