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Structural plastics conference showcases multiprocesses.

If the 21st Annual Conference of SPI's Structural Plastics Division, in San Francisco from April 25 to 28, is any indication, the group is exactly where it has wanted to be for years--more in the mainstream of plastics technology and its numerous major markets.

When the division was founded in 1973 as the Expanded Plastics Division, all its marketing strategies were based on structural foam technology. Designers, however, do not think of a specific process as a goal in itself; more eclectic, they seek the best process, or best combination of processes, to most economically meet design requirements. As a result, the division, with its exclusive emphasis on structural foam, found itself for some years isolated in a limited corner of the designer's consciousness. About five years ago, the by-then Structural Foam Division reoriented itself as the more encompassing Structural Plastics Division and set out to tap the broader diversity of plastics technology. The result has been an openness to varied processing techniques, including multiprocess approaches, which were substantially displayed in the New Product Design Competition at this year's conference, "Structural Plastics--The New Generation."

Among the 93 entries in the parts competition were 16 structural foam designs; 10 products using gas-assist technology; four coinjection products with recycled resin foam cores; and 12 reaction injection molded (RIM) parts. While injection molding was still the most represented process, the Division's policy platform--that really effective design requires playing the field of processes rather than adhering rigidly to process dogmatism--was amply documented.

As Steve Ham, technical marketing manager, Cashiers Plastic, points out, "There is now a higher level of confidence in all processes; the challenge is to make the best selection(s) for the particular objectives. The ability to mold thinner walls without sink marks on large parts, such as with gas-assist; use of counterpressure to produce housings without secondary painting, with custom-colored pellets; and using two different materials, each with its own advantages, as in coinjection, are all part of today's greater mix."

A bicycle wheel produced by Innovations in Composites, Inc., and Co-Mack Technology, Inc., the molder, made a triple sweep of the Conference Award, the Single-Part category, and the Recreation and Leisure category. Consisting of three thermoplastic 20-30% long carbon-fiber-filled-nylon support spokes, the wheel has a unique hollow construction provided by the lost-core injection molding method. Overmolding on a meltable internal mandrel with the carbon-reinforced nylon produces a strong, lightweight design for handling both static and cyclic fatigue loads.

Other winners were a 6-meter-long leaf segment, from Ingersoll-Rand Co., in the Industrial & Military category, using gas counterpressure; a 40 x 48 inch collapsible container from Perstorp Xytec, Inc., in Material Handling; a backhoe cab door, in Building and Construction, from John Deere Dubuque Works, made by RIM, in which a large steel frame is encapsulated with an impact-resistant polyurethane; an in-mold-coated polyurethane elastomer hood and dicyclopentadiene shroud processed by RIM for the Workman 3000 Series Turf Vehicle from Toro, in the Transportation category; and a pedestal irrigation controller from Rainbird, in the Lawn & Garden Category, coinjection molded with an ASA outer skin and a core of 100% recycled ABS.

Other winners were, in the Medical & Scientific category, a pressure-formed console top from Hewlett-Packard of flame-retardant ABS; in Computer & Business Equipment, a coinjected electronic book enclosure, for IBM's AS400 Mini-Computer, that combines a polycarbonate/ABS alloy reinforced with 14% nickel-coated fibers for EMI/RFI shielding, and a less expensive polycarbonate/ABS alloy for the core. A video conferencing unit from Picturetel took the award in the Telecommunications category; it uses a combination of injection molding and low-pressure structural foam parts made of PPO/PPE, polycarbonate, and ABS. Injection molding, extrusion blow molding, and coinjection molding were used with varied thermoplastics in Bissell, Inc.'s convertible hand/stick vacuum cleaner, the winner in Appliances; and in Consumer Products, gas injection was used to produce the award-winning RCA 31-inch TV cabinet from Thompson Consumer Electronics. For the latter, 23 individual parts were consolidated into a single molding; weight was reduced by 43% and cycle time by 51%. In total, all the entries composed an interesting group of cost-effective designs that emphasized refinement of materials and processing.

Structural Plastics '93 also moved strongly into the arena of environmental responsibility. The American Plastics Council's Computer & Business Equipment Group, for example, reported on the initiation of a long-term program of "product stewardship" to enhance source reduction and closed-loop recycling.
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Title Annotation:Plastics News Supplement
Author:Wigotsky, Victor
Publication:Plastics Engineering
Date:Jun 1, 1993
Previous Article:Lance Neward becomes SPE's 52nd president; ANTEC '93 draws 4700-plus to New Orleans.
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