Structural, Wear-Resistant Compound Goes Off-Road


Warn Industries of Milwaukie, OR, turned to RTP Company for a tough, wear-resistant material.

An original equipment manufacturer, Warn Industries serves the automotive industry. They make the wheel end disconnect assembly (hublock) featured on 1998 Ford Ranger 4 x 4s. The assembly contains several plastic components, including the hublock housing and end cap, which are made of an RTP Company specialty compound.

Key characteristics required in the application are extreme physical and thermal durability, along with good wear resistance.

Development of the product involved a number of `real world’ tests, including desert testing under extreme loads, where the material maintained its integrity.

Converting the hublock assembly from metal to plastic has been underway for about three years. Part design, tooling, material selection and evaluation have involved RTP Company, Ford Motor, Warn Industries and molder NYPRO in Massachusetts and Iowa. All the parties worked together to ensure the successful rollout of this new power train technology, according to Warn Industries officials.

The material selected for the application is an RTP 2000 Series (proprietary thermoplastic alloy) with glass fiber reinforcement and a wear-resistant additive.

The application involves extremely close tolerances, including +/-0.003 in. on a 1.5 in. bore, and intricate molding technology. Mold flow analysis and tool development were conducted at the NYPRO plant in Clinton, MA. The part is injection molded at the NYPRO facility in Mt. Pleasant, IA.

The tool, like the part, is extremely complex, involving multiple shut-offs and windows, according to Dan Butcher, general manager at NYPRO Iowa. "We run a variety of jobs. This one is among the most complicated," he says. "The specifications and tolerances are extremely close, dictating continuity in every aspect of the material and its molding. While it challenged us, the project’s success is certainly worth the effort."

The specialty compound exhibits excellent strength, rigidity, environmental resistance and lubricity. The material features a heat defelection temperature of 500 degrees F at 264 psi (260 degrees C at 2 MPa), tensile strength of 26,000 psi (179 MPa) and tensile modulus of 1,650,000 psi (11,369 MPa). The application withstands exposure to various abrasives including salt and sand.

The NYPRO facility in Iowa features 24 molding presses ranging from 55 to 300 tons. This operation specializes in close tolerance molding for electronic connector and automotive applications. NYPRO (tel. 508-364-9721) has 28 plants worldwide, serving the automotive, health care, electronics/communications and consumer/industrial markets.

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