Oak Brook, Ill. — Industrial drums normally have two top openings, but a customer asked Canadian blow molder Reliance Products Ltd. for a three-opening, 15-gallon drum for chemicals.
Glenn Bartlett, director of engineering at the Winnipeg-based Reliance, explained how the engineers met the challenge, without breaking the bank, in a presentation at the Society of Plastics Engineers' Annual Blow Molding Conference in Oak Brook.
Reliance only does continuous extrusion blow molding to make industrial drums. The company used proprietary collapsing blow pin technology to make the three-opening drum.
Bartlett said the customer wanted recyclable content, lower part weight and the ability for automatic chemical filling systems to remove nearly all of the product out of the drum.
There was a major Catch-22, Bartlett said, because the customer was not willing to sign a contract unless the mold was built, and the blow molder needed larger equipment to make the 15-gallon drum. The engineers asked for a $3 million investment to buy larger blow molding machine, but Bartlett said that was rejected by Reliance ownership. They did approve spending $200,000 to build the mold.
The engineers could not buy a new extrusion head that was big enough. So they built a bolt-on head extender. They cut open the machine to make it large enough to accept the head.
Bartlett said management supported the effort. "This was all trial and error," he said.
They made a new die pin, needed to reduce the variation of wall thickness.
Neck warping on the openings was a big challenge, Bartlett said. The Reliance engineers designed a part-cooling station using cool air.
"We used the blow molded flash from our drums, and injection molded it right into the molded rings," he said.
Reliance got the contract for the drums. And the company freed up money to buy a larger continuous extrusion machine for the job, Bartlett said.