Fear oflawsuits has kept many design engineers from using the gas-assist process forinjection molded parts. Gas-assist molding was a way to reduce the weight ofthick parts, improve the surface finish and reduce costs.

There's noreason to be afraid anymore, however, according to Cinpres Gas Injection, whichsays it has reached agreement to buy patents from the liquidator of Melea Ltd. Melea'spatents were marketed by a company called Gain Technologies, which had threatenedlegal action against competitive technologies.

Cinpres spent16 years attempting to prevent Melea from claiming ownership of the patent fora technique described as "spillover," a process that prevents sink and weldmarks in hollow plastic objects. James Hendry, the inventor of the process, workedfor both companies at different times.

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

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

Cinpres GasInjection describes itself as the world's leading company in gas-assistedmolding (GAM) technology and says it is the only company in the world licensedto sell the plastic expulsion process (PEP) and external gas molding (EGM).

The finalresolution of the legal case likely will allow significant expansion of thegas-assist process.

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

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