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'Scrapless' forming goes commercial.

Two small technology companies, which have long histories of R&D partnerships with major firms, are separately commercializing unusual "scrapless" forming systems for making retortable food packaging and even durable goods. In truth, they're more low-scrap than scrapless methods, but neither leaves any trim scrap from the finished product. The only scrap is from cutting flat preforms or "billets" out of multilayer sheet prior to forming.

QuesTech Ventures Inc. of Newport News, Va., uses billets cut in the shape of the finished container (round, square or rectangular), which leave a small "skeleton" of web scrap. The scrap rate is only about 20%, half that of conventional roll-fed thermoforming. SFP Container Corp., Cincinnati, uses square preforms, which leave only a little edge trim for an even lower scrap rate of about 10%.

Both companies say their stress-free, melt-phase forming processes allow deeper draws and improved statistical process control because their techniques avoid the thickness variations caused by sheet sag in conventional thermoforming.

BILLET FORMER

QuesTech's first commercial Billet Forming System (for round shapes) was shipped early this year to Rampart Packaging Ltd. in the U.K. to make seven-layer PP/EVOH retortable food tubs. The idea for QuesTech's process began in the 1960s at Shell Chemical Co. and its former U.S. Rampart Packaging unit. But the equipment wasn't developed until the 1980s by a 50/50 joint venture between Rampart and QuesTech, a defense contractor with machine-design capability. After Shell sold the U.S. portion of Rampart to James River, QuesTech proceeded alone to commercialize the billet former.

In QuesTech's patented process, billets are punched from multi-layer barrier sheet and packed in plastic sleeves. The sleeves are put into a feeding unit, which loads billets into carrier rings in metal trays. The trays travel through an oven with 56 individually controlled, ceramic heating elements arranged in upper and lower banks. Computer controls allow the billets to be heated to solid- or melt-phase forming temperatures, depending on material and package requirements. Then the billets go to the hydraulic forming press, where the trays and rings become part of the lower tool cavity. Softened billets are pressure formed into the package shape using a plug assist. A stacker takes them out of the rings and trays, which go back to be used again.

Production cost of containers can be 30% less than with conventional forming--$20 per 1000 containers vs. $30 for conventional--because of the big scrap reduction, the company says. The billet process also allows close SPC control of wall thickness and can achieve deep-draw ratios of over 2:1. For a 5-g PP container in 20 cavities, the billet former can run at 14 strokes/min for an output close to 17,000 containers/hr. The billet former is available through QuesTech's sales agent, PlasTech, in Richmond, Va., for a price starting at about $800,000. (CIRCLE 9)

SFP CONTAINER'S CHIP FORMING

SFP Container is using its first commercial Scrapless Forming System to mold five-layer PP/EVOH retort containers for a major food processor. The idea for SFP's scrapless forming was developed by Dow Chemical Co. in 1976 and the machinery was designed by Cincinnati Milacron in the 1980s. Then in 1988 SFP was set up by two former Milacron employees who had developed the equipment. SFP still licenses the process from Dow.

Besides using the technology for its own processing, SFP will sublicense its technology and supply machinery to others. Its first licensee is a Japanese company, which will use the technology for an electronics application. SFP is looking for strategic partners to develop automotive, appliance and medical applications as well.

SFP's system cuts squares from extruded sheet or roll stock. Lubricated squares are heated in a patented hot-air impingement oven, then conveyed by vacuum loader and placed in lip rings. There the squares are forged between upper and lower anvils into round preforms. This forging process adds biaxial orientation and can greatly increase impact and tensile strength, SFP says. For instance, a forged ABS or HIPS preform has two times more tensile strength and four times more impact strength than unoriented sheet, while PP has 50% greater tensile strength, seven times more impact at room temperature, and 100-fold higher impact at -40 F. Chip heating and forging can be controlled to increase or decrease the level of orientation, the company says.

SFP's production former has four cavities and can mold 25 million containers/yr. It costs about $500,000. SFP also has two single-cavity formers for customer trials and has molded other materials like ABS, filled PP, acrylonitrile copolymer and UHMWPE powder briquettes. (CIRCLE 10)
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Title Annotation:Thermoforming; QuesTech Ventures Inc. and SPF Container Corp. are marketing their plastics forming systems that result in no scrap from the molded products
Author:Schut, Jan H.
Publication:Plastics Technology
Date:Jun 1, 1992
Words:767
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