NASHVILLE, TENN. (April 7, 10:55 a.m. EDT) — An injection molded, polycarbonate windshield for jet fighters — a major plastics-in-aviation breakthrough that finally is nearing production after 20 years of work — took the top design award at the Society of the Plastics Industry Inc.'s Structural Plastics Division conference.
SPD gave two awards to EnviroTech Molded Products Inc. of Salt Lake City. Designed for use on an F-16, the 78-pound canopy took home top honors with the Conference Award. The clear, bubble-free canopy also won for the Industrial & Military category in the 53-entry design contest.
“It's a very critical program for us. It's a very exciting program,” said Forrest Day, EnviroTech's director of marketing and product development. He outlined the long history of the injection molded windshield April 1 at the conference in Nashville.
Bob Pinnell, a project manager at Wright-Patterson Air Force Base in Dayton, Ohio, dreamed up the idea of injection molding jet canopies. He now is retired.
The traditional method — bending and drape-forming heated, extruded and laminated plastic sheet — takes several days or even weeks, and costs $20,000-$40,000 for a single F-16 windshield.
“That's a pretty good amount for a piece of plastic,” Day quipped. The sandwich constructions of polycarbonate and acrylic can delaminate, causing problems, he said. An injection molded version costs a few thousand dollars.
Pinnell applied for a patent in 1983. In the late 1980s he linked up with EnviroTech, a company known for molding massive parts such T-joints for pipe and filter plates that can weigh hundreds of pounds. Delta Tooling Co. of Auburn Hills, Mich., built a giant mold.
EnviroTech specializes in a low-pressure molding process the company developed called bulk injection molding. Day would not provide many details, but he said the two-stage process first extrudes resin, then injects it into a mold.
EnviroTech molded about 160 of the F-16 windshields in 1993, and they passed Air Force impact tests. Ten years later, they're still not in production.
But at the SPD conference, Day reported some good news. EnviroTech probably will begin production molding a 46-pound canopy for a T-38 training jet later this year. And in mid-2004, the company hopes to start molding a full-size PC canopy weighing about 200 pounds for the F/A-22 Raptor.
Compared with standard injection molding, cycle times are long, at about an hour. But much of that involves slowly removing the part and carefully cleaning the mold between each shot, Day said.
“A canopy even every six hours vs. every six months, it's kind of impressive,” he said.
EnviroTech also has injection molded PC sheet stock, which then can be formed into a canopy using traditional methods. The single-layer sheet holds up better than a laminate made of layers of extruded sheet, he said.
Fifty-three parts were on display at the SPD conference, held March 30-April 1. Mike Springer, chairman of the parts competition, said about half the winners were made by gas-assisted injection molding. The reaction injection molding process was used to mold about a dozen parts, and the rest were made by structural foam, coinjection, multimaterial molding and regular injection molding.
Springer was impressed by the colorful array of parts, everything from a bright yellow portable barricade to glossy body parts for a motorcycle and a personal watercraft.
“Nobody wants to paint, so when you can mold-in color, you do it,” said Springer, sales manager of Horizon Plastics Co. Ltd. of Cobourg, Ontario.
Here are this year's winners:
AGRICULTURE/LAWN & GARDEN: GI Plastek of Newburyport, Mass., took home this award for large, red, exterior panels for Case LLC's new AFX8010 combine. Mold maker on the project was the PPD Molds Division of PPD Group Co. of Waterville, Quebec.
AUTOMOTIVE: In a twist on the usual angle of parts consolidation, three parts replaced one on the new VN bumper assembly for a heavy truck from Volvo Trucks North America in Greensboro, N.C. But the bumper assembly, using seven injection molded parts made by Mack Molding Co.'s plant in Inman, S.C., offers more design options and fuel-saving aerodynamics over the previous one-piece design that used sheet molding compound, Mack said. The parts are a polycarbonate/ABS blend. Requirements for the Class A surface are met by molding those surfaces with no core-side features, avoiding issues of sink and flow lines. A robot is used to glue molded box sections to the bumper to reinforce it, and Mack ships the entire assembly to Volvo. The bumper does not need to be primed before it goes through the paint oven. Aluminum molds were supplied by Delta Mold Inc. of Charlotte, N.C., and MSI Mold Builders Inc. of Cedar Rapids, Iowa.
BUILDING & CONSTRUCTION: Structural foam molding was used to make large, interlocking wall panels from polypropylene — measuring 8 feet long — that can be assembled quickly into partitions. Innova Packaging Systems of Ieper, Germany, molded the parts for Paneltimargo Plastics of Lichtervelde, Germany. One of the challenges for mold maker FGL Precision Works Ltd. of Concord, Ontario, was designing the two-cavity, aluminum mold with very thin but tall cores, just an inch wide and about 20 inches tall. Because the product could not have any holes at the top of the part, the cores could not be interlocked into the cavity by conventional means. Also, because the wall panels were designed to stack on top of each other, part thickness had to remain consistent from top to bottom — so the 20-inch deep cavity had a zero-degree draft. Ribs were placed every 4 inches, creating a pocket within the part that added to the difficulty of venting the mold.
COMPUTER & BUSINESS EQUIPMENT: Resembling a section of a sleek, contoured car body more than a housing for an ink-jet printer, the 20-part entry brought home a winner for Arlington, Vt.-based Mack Molding. Mack uses low-pressure structural foam to make 17 of the parts on 11 molds, and straight injection molding for three parts on two molds. The material is PC/ABS. The highly cosmetic, complex part designs are an integral part of the structure of the Veris printer from Creo Inc. of Delta, British Columbia. MSI Mold Builders produced the molds.
FURNITURE: Mack Molding and MSI Mold Builders teamed again to win the furniture category, with an overhead cabinet for an innovative office system called A3 from Knoll Inc. of East Greenville, Pa. The cabinet is mounted on a tubular frame that also holds a tentlike, soft, mesh fabric covering that gives the user privacy. Mack uses gas-assisted molding and straight injection for parts with structural requirements, and overmolds edge guards from a thermoplastic elastomer material, giving the part a soft-touch feel. The modular A3 system, available in various bright colors, also uses poly-pro-pylene and PC/ABS resins.
MATERIALS HANDLING and BEST SINGLE PART: Both awards went to Horizon Plastics' yellow tubular part, a portable plastic stretch-wrap dispenser called the Precision Wrapper. Horizon uses the structural web process to mold the strong, hollow part from ABS. A user can carry the dispenser around through a plant or office. It adjusts the tension to reduce the amount of wrap required. The customer, Tyco Plastics and Adhesives Group, will distribute Precision Wrappers to customers that buy Tyco stretch film. MSI Mold Builders produced the mold. Adamson Industrial Design Inc. of Toronto designed the product, which was developed by Gooding Walsh & Associates of Belleville, Ontario.
MEDICAL & SCIENTIFIC: Accurate Molded Plastics Inc. of Coeur d'Alene, Idaho, won for a housing for a defibrillator with 14 overmolded features, five insert-molded features and a pinpoint use of gas-assisted molding to reduce sink from the single, center boss. The customer is Medtronics' Physio Control Corp. in Redmond, Wash. Accurate provided part design consultation and mold-filling analysis, and designed and built the mold, The yellow substrate material is a PC/ABS blend, overmolded with a TPE. The black TPE runs through a series of runner networks, serving as a waterproof gasket, cosmetic parts and many other functions in a single overmolding step.
RECREATION & LEISURE: Molded-in color and shapely contours are the stars of the winning motorcycle parts injection molded by Bemis Manufacturing Co. of Sheboygan Falls, Wis. Buell Motorcycle Co., of East Troy, Mich., decided early in the design of its XB9R Firebolt, a “sport fighter” bike, to get away from painted steel and vacuum formed parts, and go with a single material with molded-in color, which ended up being a DuPont ionomer/nylon alloy. Bemis' parts include the tank-area cover that supports the rider, and a fairing/windshield assembly that has to hold up, even at very high speeds. “All the parts have to act structural at 120-140 miles per hour,” said Gary Vande Berg, engineering director for Bemis. The mold maker is CDM Tool & Manufacturing Co. of Hartford, Wis.
JUDGES' AWARD: Coinjection molding replaced hand lay-up fiber-reinforced plastic on several parts on the new Polaris Industries Inc. MSX personal watercraft — and brought home another honor for Bemis Manufacturing and CDM Tool. While hand layup still was appropriate for the hull, Polaris chose a special polycarbonate/PET alloy for other parts, such as the controls, instrumentation and storage areas. Bemis used its patent-pending, foam-core coinjection technology, which endothermically foams the core material in the die, making parts that are lighter and stronger. The foam also “lifts” any sink marks opposite ribs and bosses. The highly stylized hood and other parts are metallic base coated, then top coated with a high-gloss urethane. “They wanted a feel. They wanted to slam the hood and get a quality sound,” said Vande Berg of Bemis. The company said it used both gas-assisted molding and coinjection to mold a grab bar.
PEOPLE'S CHOICE AWARD: Awarded by a vote of attendees walking the show floor, this category ended in a three-way tie. Winners were Accurate Molded Plastics' defibrillator housing; GI Plastek's panels for the Case farm combine; and Knoll's A3 office system parts molded by Mack Molding.