Novi, Mich. — Wilmington Machinery has invested about $2.5 million in its research and development lab to demonstrate low-pressure molding with foam, or gas-assist molding, particularly for use with high-pressure molds or incorporating recycled materials.
The R&D lab has a new Lumina 2400HE hydraulic press with 500 tons of clamping force, a 50-pound shot size and platen size of 70 by 80 inches to produce parts up to 70 by 60 inches.
During the low-pressure injection molding process, an inert gas is introduced into the melted polymer to reduce the density and weight of the finished products, which have cellular cores surrounded by rigid skins.
The Wilmington lab is used to show the advantages of low-pressure molding with gas to foam the plastic, such as lightweighting; spotlight the company's technology advances; do gas-assist mold trials and pilot production runs of 500 to 1,000 pieces; and trial new materials, additives, fillers and compounds.
"We've been in business for more than 50 years and are continually improving the technology," Jim Boos, vice president of sales and marketing, said at the Injection Molding and Design Expo, held Sept. 20-21 in Novi.
Boos said he fielded a lot of questions about what low-pressure structural foam molding is, and his answers surprised many.
"I don't think a lot of industry knows you can potentially run a high-pressure mold in a low-pressure machine," Boos said. "You can bring that mold to Wilmington, and we can trial it."
Low-pressure machines typically run multiple molds at the same time, which is an attractive capability.
"If you can put four high-pressure molds in a single low-pressure machine and make four parts at the same time, that saves you from running four different machines," Boos said, pointing to savings of time, energy, capacity, floor space and labor.
Founded in 1972 to build structural foam injection molding machinery for furniture, Wilmington expanded into machinery for polypropylene handles for the brush industry then pallets and other products.
Wilmington's low-pressure structural foam machines have large platens — from 54 by 54 inches to 108 by 186 inches — and multiple nozzles capable of being arranged to fill several molds simultaneously.
The company also builds rotary blow molding machinery and systems.
With low-pressure injection molding with gas, plastics processors can reduce part weights by 10-30 percent; use nitrogen, carbon dioxide or chemical blowing agents; mold large parts with low clamp force; lower energy costs; produce complex parts without sink marks; and produce parts that can be sawn, screwed, nailed or stapled like wood.