Gas-injection opportunities expand.

Gas-Injection Opportunities Expand

With a long-running patent dispute that stymied the technology's growth in the U.S. finally settled late last year, gas assisted injection molding processes are being promoted by a growing number of players. In just the past few months, both the hardware options and technology licensing opportunities have multiplied. New patents continue to be issued and applied for, adding to the variety of methods for selectively hollowing out thick sections in molded parts. (For previous articles, see PT, June '89, p. 70; Jan. '90, p. 98; Aug. '90, p. 14).

MORE LICENSES AVAILABLE

The key factor in opening up North American potential for gas injection was the recent resolution of the decade-long legal skirmishes between Cinpres Ltd. of Tamworth, England, and Michael Ladney, former owner and president of Detroit Plastics Molding (DPM) and the current president of GAIN Technologies, Sterling Heights, Mich. Although Ladney had ceased offering additional licenses to his GAIN process while he remained at DPM (now called Automotive Plastic Technologies, Inc.), his new company is once again making licenses available to this commercially proven technology. He is offering licenses for a flat fee that varies with the size of the company to be licensed.

In addition, Ladney, who has owned the rights to the first gas-assisted process since it was developed in the late 1970s, is now offering to license a new version of his process, on which he recently received a patent (U.S. Patent No. 4,943,407, issues July 24). That process introduces the gas "upstream of the mold cavity including the runner, sprue area and machine nozzle," according to James W. Hendry, inventor of the technology. He says the new patent complements the original Friederich patent--owned by Ladney-- which covers gas injection only through the machine nozzle. (CIRCLE 90)

And this month, Sajar Plastics Inc., Middlefield, Ohio, plans to begin licensing its own patented gas-injection process, which it has been using in-house since the mid-1980s. Sajar sources would not comment specifically on how this process differs from others on the market. (CIRCLE 91)

Cinpres, which the court cleared to license its Cinpress II methods for gas injection into the runner or mold cavity (but not at the nozzle), is considering the possibility of opening a U.S. office, says Managing Director Steven Jordan.

The apparent similarity between the newest GAIN patent and the Cinpress II In-Runner process has not led Cinpres officials to fear yet another legal challenge from Ladney; nor, will they initiate any action to challenge his new patent. "Cinpress Ltd. and its associates have used in-mold gas injection processes of various types for a number of years," Jordan says. "We'll obviously use our patents to protect ourselves if we have to but litigation does nothing to further the development of this technology in the U.S."

Ladney declined to discuss the issue, saying only that he does not plan any further legal action unless a supplier clearly infringes on his latest patent.

MORE EUROPEAN VERSIONS

Three West German companies, Mannesman Demag, Battenfeld and Klockner Ferromatik Desma have introduced new processes marketed through their North American affiliates. In August (p. 14), we reported that Mannesman Demag U.S. Plastics Machinery Div., Torrington Conn., is offering optional equipment for its Gas Injection Process (GIP); and that Battenfeld of America Inc., West Warwick, R.I., has brought its Airmould process to America.

Now Klockner Ferromatik Desma, Inc., Erlanger, Ky., is introducing its Airpress III technique, on which the company has applied for a patent. This method introduces gas through injection needles in the mold after the melt has been injected. Apparently, the cavities are completely filled with molten plastic before gas injection, and the added pressure from the gas is relieved by opening "subsidiary cavities" with slides in the mold, or by allowing material to flow back toward the gate, if the passage is not frozen, Klockner says. Klockner contrasts this with other gas-injection processes where the melt first fill about 80% of the mold cavity and the gas fills the rest. Klockner claims that much improved surface finish, of the same standard as conventional injection molding, results because there are no variations of melt velocity in the mold to leave marks on the part. (CIRCLE 92)

A GAS-ASSIST ADD-ON

A repeat-cycle, gas metering controller said to be useful in hollow-core gas-injection molding has been developed by Haskel, Inc., Burbank, Calif. Spokesmen say the Model 56240 Pneumopulse provides positive, adjustable-speed control for any Haskel pump or gas booster, unaffected by load (output pressure) change. They say gas injection is among the many metering applications for which the controller is designed. (CIRCLE 93)