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Look for More Gas-Assisted Molding Designs

Look for More Gas-Assisted Molding Designs

Fear of lawsuits has kept many design engineers from using the gas-assist process for injection molded parts. Gas-assist molding was a way to reduce the weight of thick parts, improve the surface finish and reduce costs.

There's no reason to be afraid anymore, however, according to Cinpres Gas Injection, which says it has reached agreement to buy patents from the liquidator of Melea Ltd. Melea's patents were marketed by a company called Gain Technologies, which had threatened legal action against competitive technologies.

Cinpres spent 16 years attempting to prevent Melea from claiming ownership of the patent for a technique described as "spillover," a process that prevents sink and weld marks in hollow plastic objects. James Hendry, the inventor of the process, worked for both companies at different times.

Look for More Gas-Assisted Molding Designs

Melea's owner, Michael Ladney, maintained that Hendry invented the process while working for Melea. In an English trial several years ago, Hendry testified for Melea, then admitted perjury and supported Cinpres' case, according to an account on Cinpres' website. A Court of Appeal ruling in 2008 backed Cinpres, leading to the collapse of Melea.

In a new press release, Cinpres Managing Director Jon Butler says, "There can now be no further confusion - Cinpres will be the undisputed owner of all the appropriate gas-assisted technologies. Customers can now buy our technologies without fear of contested claims and counter-claims between Cinpres and Melea, or any other party."

Cinpres Gas Injection describes itself as the world's leading company in gas-assisted molding (GAM) technology and says it is the only company in the world licensed to sell the plastic expulsion process (PEP) and external gas molding (EGM).

The final resolution of the legal case likely will allow significant expansion of the gas-assist process.

That's important for design engineers because molded products are no longer restricted to certain basic design rules such as boss and rib size relative to wall thickness.

Gas-assist injection molding is defined as a process that uses nitrogen or another inert gas to create hollow channels within a part. Channels are designed into the part, improving strength and speeding cycle times. Flow channels may also eliminate the need for hot runners. Tubular sections can be designed into the product and eliminate the need for expensive undercuts and lifters in the tool. Most thermoplastics can be used in the process.
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