Canadian Plastics

Thinwall molding takes on new dimensions with thixomolding

Once the domain of a few high-end applications in plastic, the process of injection molding parts with large flow length to thickness ratios, commonly referred to as thinwall molding, is getting a boo...

October 1, 1999   Canadian Plastics



Once the domain of a few high-end applications in plastic, the process of injection molding parts with large flow length to thickness ratios, commonly referred to as thinwall molding, is getting a boost from Thixomolding, the high-speed injection molding of thixotropic materials such as magnesium and aluminum. The reason, says Tim Creasy, Thixomolding product manager at Husky Injection Molding Systems, is that in markets such as electronics and automotive, Thixomolded parts answer the simultaneous need for thinner, lighter parts with superior performance properties.

“In some cell phone applications, there is a concern of designers that if they push thinwall molding of plastic beyond a limit they will not get acceptable mechanical properties in the part,” says Creasy. “With thixomolded magnesium, that is less of a concern because magnesium is 20 times stiffer than polycarbonate.”

Thixomolding, the trade name of a process patented by Thixomat Inc. (Ann Arbor, MI), has been described as a hybrid process that effectively combines the end-use objectives of traditional die casting with the techniques and equipment of injection molding. Husky Injection Molding Systems is licensed to be the exclusive builder of Thixomolding machines in North America, South America and Europe. JSW is licensed to manufacture the machines in Asia. Both companies can sell their machines anywhere in the world.

Creasy notes that a number of laptop computer manufacturers have switched from plastics to magnesium as the choice of material for the enclosure.

“Laptop design is being driven into lower stack heights, which means thinner screens,” says Creasy. “The net effect is more powerful processors and electronics being squeezed into a smaller enclosures and more heat.” Magnesium, in this case, allows designers to build thinner wall sections without sacrificing strength. It also provides EMI shielding and acts as a more effective heat sink than plastic,.

Another area where Thixomolding is likely to expand is the automotive market. Fuel efficiency standards are driving the automotive companies to make lighter cars and trucks, yet this must be accomplished without compromising the structural safety of the car. Thixomolding provides a way to make lighter vehicles that are structurally safe.

“There’s a lot of interest among OEMs in the use of magnesium in instrument panels,” Creasy reports. Making a Thixomolded IP will become more viable once larger tonnage Thixomolding machines are built. Husky has plans to build a 1000 tonne Thixomolding machine in the near future.

Creasy observes that most of the companies buying Thixomolding technology are plastic injection molders. In order to enter Thixomolding a company must pay an up-front fee to purchase the technology from Thixomat, a one-time per machine fee and the cost of the machine.


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