The PEM R'Angle self-clinching fastener (type RA) from Penn Engineering and Manufacturing Corp. in Danboro, Pa., is designed to provide a strong right-angle attachment point for mating aluminum panels or sheets as thin as 0.04 inch, eliminating the need for bent tabs and flanges, right-angle brackets, or tack-welding operations.

PEM R'Angle self-clinching fasteners (inset) ease the assembly of this enclosure for an electronic paint scale manufactured by Fillon Pichon.

The extruded aluminum fastener can also improve shielding from electromagnetic interference and radio-frequency interference due to the elimination of cutouts in panels.

In use, the self-clinching fastener is pressed into an appropriately sized rectangular punched hole in an aluminum sheet. The fastener mounts securely and permanently, with the reverse side of the panel remaining flush. The R'Angle fastener is then attached to a second sheet with a standard thread-forming screw. The result is a tight fit that resists vibration and has good strip-out characteristics.

The new fasteners found a use when Fillon Pichon USA Inc. in East Providence, R.I., selected them to serve as strong right-angle attachment points in the two-piece enclosures for its precision F7000 digital electronic paint scales. The six PEM R'Angles reduced the amount of hardware used in half, slashed per-unit assembly time from 11/2 hours to 15 minutes, and eliminated two fabricating steps altogether.

"We were looking for production economies, standardized hardware, and performance," said Art Bernier, systems manager at Fillon Pichon. "We found them with R'Angle fasteners."

Although Carilon was introduced only recently, the polymer is establishing itself as a useful engineering thermoplastic for applications in the automotive, business-machine, and electronics industries. "The great strength of Carilon polymers lies in their combination of properties such as inherent toughness and excellent solvent resistance," said Jamie Tebay, LNP's product-marketing manager.

"They have attracted a great deal of interest in the automotive industry because their resistance to fuels and fluids is much better than nylon 12's," Tebay added.

Other key characteristics include good impact resistance over a wide temperature range, superior resilience and "snapfitability," low water absorption, and suitability for short molding cycles.

Carilon-based N-series composites are available in a variety of grades with reinforcements including carbon, glass, or aramid fibers. These grades offer an attractive combination of strength and stiffness, along with low-wear properties.

The addition of a lubricant improves wear resistance. "Because of their excellent tribological properties," Tebay said, "lubricated Carilon composites are especially effective in gears, seals, bearings, cams, pulleys, rollers, and levers—applications where moving parts come into contact and wear resistance is required."

Prozinc 500 reinforcing rods are specially treated with zinc to resist severe corrosion attack.

Unlike conventional galvanized steel, Prozinc 500 is treated using the Delot process in which wire is shot-blasted, induction-heated, and passed through molten zinc at a rate greater than 500 feet per minute, altering its internal structure. This processing means the rods can be bent, welded, and formed without damaging the protective zinc coating.

Applications for Prozinc 500 include seacoast construction, bridges, reservoirs, swimming pools, and power-generation and water-treatment facilities.

The new Impet Hi 430 PET resin, which contains only 15-percent glass, is easy to injection-mold and causes relatively little tool and machine wear. The new resin flows easily without high injection pressures, which can overstress tools and machines.

The development of the toughened PET "has important implications for designers of structural parts," said Ticona program director Steve Leyrer. "It now enables them to select a more-affordable, easier-to-mold material for high-impact applications." Several recent breakthroughs have enabled researchers to make a PET grade that is much tougher than conventional PET grades and more durable, even at low temperatures.

At —20°C, for example, the material exhibits 40 percent higher notched impact strength (8.8 kilojoules per square meter) than conventional glass-reinforced PET resins. Ticona's compounding technology has given traditionally brittle PET more ductile failure modes and greater impact strength for these demanding structural applications. The new resin also provides good weather resistance, recyclability, and colorability.

A variant of the Impet Hi 430 PET grade is being used in the Chrysler Corp.'s Composite Concept Vehicle (CCV) (see "Plastic Cars for Developing Nations," November 1997). The polyester parts for the CCV body are the largest components ever molded in an engineering thermoplastic. The new Plymouth Pronto Spyder concept sports car uses another variant of the new PET formulation in its molded car body.

"Molded-in color eliminates painting and the handling associated with painting," Leyrer said. "Every time you handle parts, you add to their cost."

Groendyk's Lite cellular silicone sponge provides a low-density solution for cushioning, gasketing, sealing, and insulating applications.

The sponge meets or exceeds BMS 1-68 material requirements for fire resistance, compression deflection, temperature range, compression set, elongation, water absorption, and aging. The product also features low thermal conductivity and high thermal resistance—important concerns in heat-management and insulation applications.

Airbus Industrie has substituted Victrex's PEEK polymer for aluminum in several small components found on its airliners.

"Cost reduction and weight savings are essential requirements of the global aircraft industry," said Marianne Morgan, transportation market manager at Victrex. "By using PEEK polymer in place of aluminum, Airbus Industrie has been able to realize a 50-percent reduction in part weight and a cost savings of up to 75 percent." The PEEK polymer also exhibits excellent flame retardance, a key factor in aircraft-safety design.

After extensive testing, Victrex PEEK 450GL30, a 30-percent glass-filled composite grade, was chosen for the cable clips and extruded cable conduits. The selection was based on the material's excellent flame-retardance ratings, which include good self-extinguishing characteristics as well as low smoke and combustion by-product toxicity.

In addition, the material met requirements for good mechanical strength and resistance to hydraulic oils and kerosene. For star-shaped cable clips, a 20-percent glass-filled Victrex PEEK polymer was chosen for its balance of flexibility and stiffness, UL 94 V-O flammability listing, and good chemical resistance.

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© 1998 by The American Society of Mechanical Engineers