OAK BROOK, ILL. — Nearly 30 years ago Boeing Co. in Seattle got into rotational molding.
Unfortunately, the company selected the wrong material for the application. Beginning in 1968, Boeing used polycarbonate resin to rotomold airplane air-conditioning duct systems. But the PC parts quickly deteriorated, according to Jack Woods, principal engineer in the research and development of secondary structures for Boeing Commercial Airplane Group.
By 1973, frustrated engineers decided that the rotomolding process itself was the problem. By 1975, only a few rotomolded parts remained on Boeing's planes and, for the next 14 years, the process was all but abandoned, Woods said in a seminar presentation at ARM's fall meeting, held Oct. 5-8 in Oak Brook.
Later, Boeing discovered that solvents used in pesticides in Asia to defumigate airplanes were responsible for the rapid deterioration of the PC parts.
In 1989, a new generation of Boeing engineers looking for ways to save money in parts production revisited rotational molding.
This time, Woods said, the company picked a specially formulated nylon 12 material to mold duct parts. Now, the rotomolding process once again has taken off at Boeing.
``Light and stiff is what we're looking for in parts. All the parts we make have a nominal thickness of wall of 0.050 inch,'' or just under one-sixteenth of an inch, Woods said.
Plus they must be resistant to chemicals and meet specific smoke and toxicity requirements, he added.
Today, the airplane manufacturer produces 623 rotomolded parts for use on all models of its aircraft. Each part is designed on a computer and produced from machined aluminum molds that Boeing makes.
The company produces the duct components on two Ferry machines, an RS3280 and RS4160, at a significant cost savings, according to Woods.
``Since 1991, rotational molding has enjoyed nothing short of a renaissance at Boeing,'' he said.
