The company initially changed the design of the armrests from tubular steel to plastic, molded in a gas-injection process. The plastic part combined desirable qualities of finish, strength, and weight. In the gas injection molding process, inert gas—usually nitrogen—is injected into the part during the plastic injection molding cycle. The hot gas cores out a hollow center, resulting in a lighter part. Other advantages of the gas injection molding process include improved packing out of the plastic in the mold, minimized volumetric shrinkage, and the ability to mold a part on a lower-tonnage press.

Club Car's polypropylene canopy was made using a gas injection molding technique.

The company then set its sights on producing the cart's canopy using the same process. The canopy on the previous cart model had been vacuum formed of polypropylene. The goal now was to improve the appearance of the canopy, while maintaining the rigidity and durability of the roof part, which was required as a structural member. The polypropylene injection molded part would require a number of details, including water channels, hand holds, punched holes for steel roof supports, and provisions for windshields and other accessories, said Club Car's chief designer, Don Samuelson.

Originally, the company considered a blow-molded part, but opted for the gas injection molding process to meet styling and functional requirements, including the shape of the water drainage system and structural elements, according to Jeff Hyndes, manager of mechanical engineers and golf products. The gas-injected part provided coring that increased the part's bending stiffness compared with the flatter geometry of the original part.

Club Car worked with Thomson Plastics, an injection molder in Thomson, Ga., and Cinpres Ltd. North America of Ann Arbor, Mich., the supplier of the gas injection equipment and technology. The part measured 2,520 square inches, one of the largest to be produced with the gas injection process, according to Cinpres. After initial evaluation, the companies worked with the moldmaker, Model Die & Mold Inc. of Grand Rapids, Mich. The mold was straightforward for such a complex part: It incorporated a single plastic feed point and two Cinpres 10-mm gas nozzles. This was achieved by paying attention to the cooling channels and using high conductivity materials in selected areas.

Once the mold was completed, the team worked with the material supplier, Montell North America of Wilmington, Del., to achieve the proper details, surface finish, and structural integrity, while avoiding lines and sinks that could occur with such a large molding. The gas injection process helped achieve the strength and high load and deflection requirements with a minimum of material—18.4 pounds per shot. The designers were able to incorporate the desired details into the part with the required surface finish, smooth radii, and structural integrity. The gas injection process allowed strengthening ribs and sections to be incorporated, without unsightly lines and sinks that could result in such a large molding.

Thomson Plastics was able to mold the part on a much smaller-tonnage press—2,200 tons versus the 6,000-ton model originally considered. The injection-molded canopy exits the mold with all the features already in place and mounting holes formed, eliminating most secondary operations for assembly. In all, the number of parts on the canopy was reduced from 54 to just nine.

After a materials evaluation, the company opted for Stat-Kon M1-HI UV, a high-impact, statically dissipative poly-propylene composite, from LNP Engineering Plastics in Exton, Pa.

The fuel filler pocket of statically dissipative composite eliminates the need for a ground strap.

Switching to the composite for the housing allowed DaimlerChrysler to reduce its costs by eliminating the expensive ground strap, according to the company's project engineer, Nancy Isles. Use of the composite ensures that when the housing is screwed onto the vehicle, the housing is grounded.

"We don't have to attach the ground strap because the fill tube is grounded directly through the housing," Isles said. Switching to the composite housing eliminated an assembly step in the plant.

"Because this is an exterior exposed component, the company required a material with UV properties that would resist fading or changing color," she said. The composite also had to meet DaimlerChrysler's exterior design requirements. "Our team is very pleased with the appearance of the material," Isles said. "It has a softer, less shiny appearance, which is perceived by consumers to be higher quality than shiny plastic."

High impact strength is also important. "We needed a material that was strong enough to hold the housing in place, plus it had to survive our impact tests," Isles said.

Put it all together and you have a lot of energy going into rapid back-and-forth movement involving acceleration, deceleration, and torque. If the washer tub was rigidly mounted to the cabinet, there would be continuous thrashing and noise, resulting in extremely heavy stresses and strains placed on transmission and agitator parts.

Whirlpool designs stress, strain, and noise out of its washers by floating the tub on a smooth triangular surface, a little like a three-sided household step stool, situated between the cabinet base and the bottom of the tub/agitator assembly. At the bottom of the tub, a smaller triangular mating surface is free to slide on the larger step, allowing a few inches of movement on the horizontal plane. Between the two triangles, snapped into the bottom triangular surface, are three small but critical plastic pads, each roughly 1 square inch, which act as bearing plates.

Whirlpool washers keep spinning with pads (lower right) that are made of acetal, PTFE, and silicon.

Traditionally, these pads had been injection molded from a homopolymer acetal lubricated with polytetrafluoroethylene, or PTFE, fiber. The original material, although expensive, provided the correct combination of properties to ensure that the pads would have the right combination of long life, low friction, and freedom from stick-slip. Recently, Whirlpool set out to find a thermoplastic that would provide the same attributes in a lower-cost plastic resin.

Working with a handful of resin suppliers, the company narrowed the field of candidates from 17 materials, before choosing Lubri-Tech ATH-XC361E, a custom-formulated, self-lubricated homopolymer acetal with PTFE and silicone, from M.A. Hanna Engineered Materials, a unit of the M.A. Hanna Co. in Cleveland.

Whirlpool tested the materials, focusing on steady-state linear wear rate, steady-state temperature, break-in period, dynamic coefficient of friction, pressure resistance, machine walk and vibration, and mechanical strength. The testing simulated levels of spin cycle imbalance, which is the time when the pads move the most and at the highest rate.

Lubri-Tech ATH-XC361E compound provided the required mechanical characteristics at a significant savings over the material originally specified by Whirlpool, said Guy Mendes, global procurement commodity manager for resins and finishes at Whirlpool. M.A. Hanna developed Lubri-Tech ATH-XC361E compound for applications under heavy physical load that require lubricity and minimum wear. The compound combines lubricating additives and silicones with the base acetal homopolymer.

According to Van Le of NetMotion, "Unlike conventional metal tweezers, which are often used to handle wafers, wands made with PEEK polymer are nonmetallic so they never scratch the surface of the wafer. Scratching produces particles that can cause contamination. The area that contacts the wafer surfaces is optically polished to reduce surface particle counts. Because PEEK polymer is an inherently pure material with few trace elements, it minimizes the risk of contamination."

A marketer of semiconductor wafer handlers of PEEK polymer says that the product ensures purity.

The manual wands used for wafer handling are made entirely of PEEK polymer, supplied by Victrex USA Inc. of West Chester, Pa. They are designed to ensure that the wafers are handled softly, without excessive touch. The vacuum wands are used for semiconductor wafer processing and only the tips are made with PEEK polymer. The tips are optically polished to provide excellent adhesion to the wafer.

PEEK polymer has enough strength to handle wafers up to 12 inches in diameter, Le said. The material offers superior corrosion resistance and meets manufacturers' demands for abrasion resistance and reliability, he added.

One advantage of PEEK polymer is the material's high continuous service temperature. "Because the semiconductor wafers are often processed in a high-temperature environment, any equipment that's used in handling must be able to withstand temperature extremes," he said.

The PEEK polymer used for the wafer is reinforced with carbon fiber to reduce electrostatic effects. "Even minute amounts of static electricity can damage electrical circuits on the wafer and result in major economic losses. The polymer's resistance of 106 to 108 ohms provides optimum static performance," Lee said.

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