The two Thixomat Inc. machinery licensees - Japan Steel Works Ltd. and Husky Injection Molding Systems Ltd. - each made news at two recent magnesium molding conferences.
JSW, which has sold 211 Thixomolding machines since 1997, won the Process Award at the International Magnesium Association's World Magnesium Conference, held May 19-21 in Montreal.
Meanwhile, during the International Thixomolding Magnesium Conference, held May 22-24 in Toronto, Husky introduced its first mass-market injection press for magnesium molding. Conference attendees toured Husky headquarters in Bolton, Ontario.
JSW calls its magnesium machines JLM presses. During the Toronto event, JSW's Hiroshi Seshimo, manager of press sales for magnesium, outlined the Hiroshima, Japan-based machine maker's history with the technology.
The firm built its first Thixomolding prototype, a press with 450 tons of clamping force, in 1993. Three years later, it built a large JLM, an 850-tonner.
JSW branched into molding magnesium itself in 1997, setting up MG Precision Co. Ltd. next to its technology center.
JSW has sold 146 Thixomolding presses to Japan, 36 to Taiwan and 19 to North America.
Taiwan is a big growth market. Seshimo said Thixomolding has a 47 percent share of personal- computer enclosures made in and shipped from Taiwan. The technology now is moving into processing in China, as Taiwanese electronics makers move production to China.
Another JSW speaker, Isao Nakatsugawa, chief engineer of research and development for the magnesium process equipment and products division, showed a video of a hot-runner seat back for a car, molded in Japan. Normally, injection molding of magnesium alloys uses large cold runners that must be removed after molding.
At the Toronto conference, the company announced that its U.S. operation, JSW Plastics Machinery Inc. in Elk Grove Village, Ill., now will handle North American sales of the JSW magnesium presses. Since 1999, the U.S. unit has handled service and parts for the machines, but sales were handled directly from Hiroshima.
Husky formally launched its first commercial magnesium molding machine with a tour May 24. The firm had developed the technology for several years, and had sold a few prototype presses.
The new Thixomolding presses are based on Husky's Hylectric machine platform. To withstand the rocket-fast injection speeds, and shock and vibration caused by magnesium molding, Husky bulked up the injection housing, and added standoff blocks to transmit force from the injection unit through the housing and directly to the platen.
The entire press is fully guarded and self-contained, to hold in any flash. A special ventilation system filters out the mold-lubrication spray, said Zac Glasford, Husky's Thixomolding project engineer.
During injection, the magnesium first has to blow out a plug of semi-solid material, then the melt blasts into the mold. Glasford used food analogies to describe the thixotropic melt.
``I see Thixomolding as being like a Slurpee,'' Glasford said as the machine thunked away. ``You have solids, which is the ice, and you have the liquid. Some Slurpees you get are quite hard, quite viscous. There's a lot of ice in there, and you can't suck it in. We try to have our plug something like that.''
He compared a hard plug with a ketchup bottle. ``You've got to smack the bottom to get it free,'' he said, which is not good.
Two other Japanese injection press makers that are not Thixomat licensees also have new magnesium molding machines. Japan's Sodick Plustech Co. Ltd. this year introduced a magnesium molding press called MG Plus, in clamping forces of 40, 80 and 260 tons.
The press uses Sodick's patented plunger injection technology. Instead of pellets, Sodick uses a loading system of magnesium bar stock. Under high heat, the bar stock gradually is transformed into a molten state, then the material is injected into the mold.
The press will be ready for North American sale in the third quarter. In North America, Sodick machines are distributed by Yamazen Inc. of Schaumburg, Ill.
Another Japanese firm, Ube Machinery Inc., offers a press called NRC, for New Rheo Casting. But Ube markets the machine to die-casting companies, not plastics molders, according to Masa Shiragaki, director of die-casting sales at the Ann Arbor, Mich., firm.
Ube has sold four NRC machines to U.S. customers. The machines make thick-wall parts, such as automotive steering column components, Shiragaki said.