A team approach overcame a cosmetic blemish that marred last year's introduction of a 15-inch contoured gas-assist poly-propylene door handle on a new line of Frigidaire Co. refrigerators. ``We overcame some production challenges and obstacles and are pleased with the parts now,'' said Tim Palmisano, buyer with Frigidaire's refrigeration products division in Greenville, Mich. The color defect appeared at the transition or hesitation line that can occur in the gas-assist process.
``We reinvented the wheel with a different material, different gas-assist process and a four-cavity mold,'' said Eric Rouch, application development engineering manager for injection molder Jones Plastic & Engineering Corp.
Ferro Corp.'s filled and reinforced plastics division in Evans-ville, Ind., solved the riddle.
``We had expert technical engineers on gas-assist, design and processing look at the problem,'' said Kurt Schuering, division manager of market development.
Ferro custom-formulated a material to eliminate warpage and provide a consistent color. Ferro achieved a flexural modulus of 400,000 pounds per square inch and compounded special additives to lubricate and help the material crystallize faster.
``The problem was a mix of molding and gas-assist,'' said Steven Johnson, vice president of sales and marketing for Nitro-Jection Corp. in Chagrin Falls, Ohio. ``Such a thick part can't be done on conventional molding.''
In gas-assist processing, the mold is filled 60 percent, and then the nitrogen comes in to speed the material into the cavity.
``The new compound reduced the visibility of the hesitation line,'' Johnson said. ``Our technology can introduce nitrogen through the machine nozzle or pins in the mold. This multicavity tool uses the machine nozzle process.''
Now, Jones Plastic uses Ferro's 10 percent glass-filled PP and NitroJection's Deluxe gas-assist processing unit to mold the handle and its curling ends in five colors on a 500-ton Cincinnati Mila-cron press in Jeffersontown, Ky. Production began in February.