Thixomolding taking aim at automotive

Husky Injection Molding Systems is betting that the magnesium injection unit displayed at its booth during NPE will soon have a big impact on parts manufacturing. Built to run on the Hylectric machine platform, the THX500 injection unit is the engineering culmination of a carefully thought-out strategy to build reliable, cost-effective Thixomolding molding machines targeted for the consumer electronics and, especially, automotive industries.
“We want plastic injection molders to be comfortable with this technology,” said Pierre Pinet, Husky’s project manager for Thixosystems. “Thixomolding is something a molder can run as a compliment to their core molding business.”
Husky is one of two machinery OEMs (the other being JSW) licensed to manufacture Thixomolding injection machines. Husky began developing a Thixomolding machine prototype based on its G series of machines. After initial trials, however, engineers realized the injection unit needed to be redesigned to accommodate magnesium.
“We didn’t think the old design was optimized for magnesium,” Pinet said. “We feel this new unit is going to get us there.”
Pinet said Husky engineers focused redesign efforts on three main areas of the injection unit: the barrel, the hydraulic system and the heating system.
The new design incorporates a large cradle, which supports the barrel and eliminates the transmission of load forces along the length of the barrel wall. This in turn allows for a thinner barrel wall, which improves conduction of heat.
“With plastic, the majority of heat (to melt) is supplied by shear forces. With magnesium the main source of heat is resistive style heating elements that transmit heat through conduction,” Pinet said.
The redesigned barrel not only enhances throughput, thus allowing Thixomolding to compete with cycle times of die casting processes, but also more readily accommodates larger tonnage machinesthe type of machine needed to mold larger parts for the automotive industry.
Pinet said Husky plans to begin testing a prototype 1000-tonne Hylectric Thixomolding machine at its Advanced Manufacturing Centre in Bolton, ON by the end of 2003. Husky and several partner companies have been conducting trial tests on the 500-tonne Hylectric Thixomolding model introduced last year. Pinet says he anticipates the first sales of the 500-tonne model in the very near future.
“There are about 250 Thixomolding machines in use around the world, with the majority of these molding consumer electronics parts in Asia. We (in North America) have a market at our doorstep in the automotive industry. All it’s going to take is a couple of key applications to prove Thixomolding is a viable model for parts manufacturers.”