The composite fuselage of Raytheon's Premier I business jet is fabricated automatically by a Viper fiber-placement system from Cincinnati Milacron.

The Viper FPS eliminates the hundreds of pieces and long assembly cycles of traditional aluminum aircraft construction, as well as the time- and cost-intensive hand lay-up of components that is typical of composite construction. The monolithic composite construction—a sandwich of inner and outer carbon-fiber layers around a middle layer of honeycomb material—gives rise to several design and performance advantages and production efficiencies, according to Milacron spokesmen.

The fuselage is 20 percent lighter than the same structure in aluminum. In addition, reduced wall thickness—only 0.81 inch—translates into greater cabin space. The fuselage production cycle takes just over a day.

Milacron's seven-axis Viper system automates fuselage manufacture through fully programmable composite tow placement and in-process lamination. Building composite structures tow by tow, the Viper FPS follows complex contours with seven axes of CNC motion. The tow lay-up is performed automatically: feeding, tamping, cutting, and restarting tows as needed to place window and door openings.

The machine can manipulate up to 24 tows at once—each up to 0.125 inch wide—by using programmable bidirectional tensioners mounted in an air-conditioned creel.

The LOMComposite (LGF 045) material is said to be six to nine times stronger than the company's standard LOMPaper build material, according to Michael Feygin, president and chief executive officer of Helisys. Moreover, LOMComposite has demonstrated z-axis growth of less than 0.4 percent in moist conditions (90-percent relative humidity). LOMPaper is susceptible to exposure to atmospheric moisture, which causes it to grow or expand.

LOMComposite consists of a base layer of nonwoven, randomly oriented glass fiber mixed with a ceramic material, which is secured in place by a thermoplastic binder, Feygin said. A layer of thermosetting epoxy lines the underside of the material. During lamination on one of Helisys' LOM 2030H machine, the binder and epoxy diffuse into each other, he said, forming a bond.

When tested recently at a dozen beta sites, the tough new LOMComposite material maintained good dimensional stability when subjected to various severe environments. Beta-test applications included injection molding, powder metallurgy, sand casting, silicon rubber molding, vacuum forming, and wax injection-molding tooling.

Engineers at DANA Corp. in Toledo, Ohio, for example, built male and female injection-mold halves of a part and sent it to Toledo Mold & Die for evaluation. Results were quite satisfactory, according to DANA spokesmen.

The 1997 Corvette features a molded polyurethane seat-back frame that is 60 percent lighter than the steel part it replaced.

The engineers chose to replace a tubular-steel seat-back design with a glass-fiber-reinforced polyurethane composite produced using the Baydur 410 IMR polyurethane high-density SRIM system from Bayer Corp.'s Polymer Division in Pittsburgh. The nonmetallic component trims 60 percent of the weight from each of the Corvette's two seat-back frames without sacrificing strength. The finished seat-back frame weighs 3.7 pounds.

Polyurethane SRIM also enables Lear Corp. in Southfield, Mich., the seat-back supplier, to cut the frame fabrication process to a single step and produce two different frames with the same mold.

According to Bayer, the Baydur 410 IMR system offers high strength and stiffness, light weight, design flexibility, and the opportunity for parts consolidation. The 410 IMR-modified system provides an internal mold-release feature that significantly reduces cycle times and improves processing productivity. Using a glass-fiber mat reinforcement, Lear is posting shot times of 6.5 seconds, cycle times of about 90 seconds, and mold temperatures of 160°F.

"This is the first mass-production polyurethane SRIM seat-back frame in the North American auto industry, and probably the first in the world," said Lear product engineer Michael Walkowski.

These Dodge Durango body panels are supported in precise location by an Alufix fixturing system.

Each bar of Alufix is machined on all sides to an accuracy of 0.01 millimeter for flatness, parallelism, squareness, and the center-to-center distance between holes. Bars are available in three sizes: 16, 25, and 40 millimeters (these figures designate the distance between the centers of the holes in the patented grid pattern).

The Alufix system features a large selection of reusable modular fixturing components to accommodate parts both large and small. The fixturing components include bars, struts, quick-connection devices, off-grid components, blank blocks for machining of net pads, clamps, vises, vee blocks, and screw jacks.

The Alufix system offers several advantages over conventional fixturing methods. Assembly time is reduced, and there is no need to block a CMM to use it. Last-minute design changes can be easily accommodated in-shop. A fixture may be designed with detachable sections to allow for simultaneous work at different locations.

According to Alufix's U.S. distributor, Paul W. Marino Gages Inc. in Warren, Mich., General Motors Corp., Ford Motor Co., and Chrysler Corp. have all used Alufix in prototype or production applications.

Pawnee Rotational Molding Co. in Maple Plain, Minn., has had success using a rotomolded plastic part in the Panda 6080 Power Sweeper frame, which supports an indoor/ outdoor sweeper that's been in production since mid-1997. The design simplified the sweeper by replacing more than 120 steel parts with just one rotomolded polymer part.

The frame of the Panda 6080 Power Sweeper is a single rotomolded plastic part that replaces a complex steel assembly.

Used when other plastic forming processes are difficult to apply, rotomolding results in seamless, hollow parts with little or no waste. In the rotomolding process, powdered plastic is placed inside a heated mold that is made to revolve about two axes. The rotation evenly distributes the material over the inside mold wall, leading to high-integrity parts.

The drastic reduction in the number of parts results in reduced vibration, prolonged machine life, and decreased operator fatigue. The frame weighs 45 pounds, compared with its steel predecessor's 100 pounds. This weight reduction saves on both the horsepower required for propelling the unit and the unit's shipping costs. The finished sweeper consists of the frame and eight additional rotomolded parts.

Researchers at W.R. Grace & Co. in Boca Raton, Fla., and the Department of Energy's Brookhaven National Laboratory in Upton, N.Y., have developed a method to destroy asbestos in fireproofing installed on structural building columns and beams without lessening the existing fire-resistive performance of the material.

The new technique uses a foamy solution sprayed directly onto asbestos-containing fireproofing coatings. During the two-day treatment, the acidic foam chemically digests asbestos fibers, dissolving them into harmless chemicals. When the process is completed, the fireproofing is no longer a regulated material. The process, said to be the first of its kind, should lead to a cost reduction of 50 to 75 percent. Current techniques for removing asbestos-containing fireproofing require airtight barriers as well as labor-intensive scraping and reinstallation.

The original fireproof coatings, which are typically a few centimeters thick, contain up to 15 percent (by weight) of chrysotile or white asbestos. The remainder is an inert mixture of gypsum and a silicate material. The asbestos fibers themselves are hollow tubes of magnesium and silicon oxides.

"The foam looks like shaving cream," said Leon Petrakis, the senior scientist in charge of the Brookhaven team. While he did not reveal the treatment's composition pending patent protection, Petrakis said that it contains various acids with a small addition of fluoride ions. "The foam acts catalytically to break the asbestos down," he said. According to the Brookhaven researcher, full-scale tests confirmed that the new treatment reduces asbestos content to less than 1 percent.

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