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New licensing deal for gas injection.

The smoke from recent legal battles appears to be clearing from the field of gas-assist injection molding. While echoes of a few continuing legal skirmishes can still be heard, recent developments make it a lot simpler for most molders to practice this promising technology safe from legal challenge.

At the recent SPI Structural Plastics '91 conference in Atlanta, a panel discussion on gas-assist was well attended. At that meeting, a North American licensing agreement was announced between England's Cinpres, Ltd. and Battenfeld GmbH of Germany. The agreement provides North American users of Battenfeld's Airmould gas-assist process the option of purchasing protection from legal challenge by Cinpres. Molders will be able to obtain this protection by paying a patent-only license fee to Cinpres, says Steven Jordan, Cinpres managing director. Cost of such a license is about $9000 per machine, or $44,650 for a whole company, payable one time only. Previously, such patent-only licenses were more complicated and obtainable only on a companywide basis.

Under the agreement, molders will receive training and technical support from Battenfeld. Battenfeld won't provide licensing itself, but will sell gas-assist equipment. Battenfeld will soon have a gas-assist specialist based permanently in the U.S. at Battenfeld of America, West Warwick, R.I. Jordan says a U.S. office for Cinpres is planned. And Jordan says he anticipates other press manufacturers-including Mannesmann Demag, Engel, Klockner, Stork and Krauss-Maffei-will now enter into similar agreements.

Cinpres also revealed that it has signed General Motors Corp. to a full manufacturing license for the Cinpres II process, including a development phase. Cinpres II entails using a pin as an injection port for a nonreactive gas to enter an injection molded part through either the sprue or cavity directly. It differs from Cinpres I, which injects gas into the melt at the machine nozzle. Cinpres I has been found to infringe on patents held in North America by Michael Ladney, president of GAIN Technologies, Inc., Mount Clemens, Mich., the primary owner of U.S. patents on gas-assist technology (see PT, Oct.'90, P.37).

At Structural Plastics '91, James Hendry, 70, sometimes referred to as the "father" of gas-assist, revealed that he would not renew his contract with GAIN, which expired in April. Instead he plans to become a freelance consultant from his Brooksville, Fla., home. Hendry worked the last four years under contract as a full-time technical consultant to GAIN.

Another scheduled participant in the Structural Plastics session withdrew from the program at the last minute. Indra Baxi of Nitrojection Corp., the recently formed gas-assist licensing div. of Sajar Plastics, Inc., Middlefield, Ohio, offered no reason for his absence. But a jury in Oakland County, Mich., on April 22nd ruled against Baxi and awarded a $2.25 million judgement to Michael Ladney in a three-year-old lawsuit involving gas-assist. Neither Sajar nor Nitrojection was involved in the suit, which was filed by Ladney against Baxi personally regarding technology that Ladney and Baxi shared through a complex patent ownership arrangement. Baxi plans to appeal the award.

John Erickson, sales manager at GAIN, says he believes the ruling will eliminate Sajar's ability to use the patented technology involved in the suit for products shipped out of North, Central or South America.

The patented technology covers the simultaneous injection of gas and resin into a mold during the injection process. Other gas-assist processes call for nearly complete filling of the mold before gas is injected.


Despite legal hassles, suppliers continue to push the technology. At the Interplas'90 show last November, Cinpres introduced a multi-cylinder conversion unit that allows gas to be introduced at different pressures at various points within a mold (see PT, Oct.'90, p.14). Separate channels can be incorporated into the runner, a single part, or different-sized cavities of a family mold. The process allows elimination of any channel designed into a part solely for gas transport.

Conversion units are offered with up to four gas cylinders. Gm's Inland Fisher Guide Div. in Troy, Mich., has ordered a three-cylinder unit.

Advanced CAE Technology, Ithaca, N.Y., is offering what's said to be the first commercial simulation for gas-assisted injection molding (see PT, Jan. '91, p. 14). C-Gasflow is said to address the complex filling dynamics encountered in the process.

Because the filling dynamics are affected by the properties of the gas and gas entry points, injection molding simulation programs designed for a single material aren't suitable for gas-assist, say Advanced CAE Technology sources. C-Gasflow simulates the initial filling of a polymer, followed by the injection of pressurized gas through the sprue or other locations in the cavity at a specified time.

C-Gasflow differentiates materials based upon the time instant and locations of their entry into the cavity and traces distributions of polymer skin and gas core during the entire molding process. In addition, the simulation accounts for the differences in material properties and the heat and momentum interactions between the polymer and gas.

While Advanced CAE Technology claims to have been first, Plastics & Computer, Inc., Montclair, N.J., demonstrated at last month's NPE new FaGain software for the simulation and optimization of gas co-injection.


Bruce Schafer, v.p. of Automotive Plastic Technologies, Inc. Heights, Mich., which was once owned by Ladney, says it has 26 tools in production with gas-assist, with more than 3.5 million parts produced to date. Schafer reports APT has tried out more than 92 tools for many different customers.

Schafer says a problem with gas-assist molding is that those pushing it are machinery suppliers, engineering firms and a very small licensing group. He says none of these groups are molders, notes that gas-assist is a technical process, and claims that most of the patents filed do not work in a production environment. He says APT sorts the illusions from the realities and produces parts as a normal activity.

APT also offers a development and production license with an indenification clause.
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Title Annotation:gas-assist injection molding
Author:Fallon, Michael R.
Publication:Plastics Technology
Date:Jul 1, 1991
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