What is Thixomolding®? Thixomolding® is a fabrication technique, similar to injection molding, that uses magnesium alloys as the “resin” instead of plastic. Solid magnesium alloy pellets are fed into the machine, heated to high temperatures and injected into a closed die / mold. Parts from the machine usually need no additional machining, finishing or puttying.

Who uses this technology? The process is used worldwide by over 40 different companies running over 200 machines. These companies supply to electronic, automotive and consumer product industries. Parts have been made as large as automotive seat frames and large screen television cabinets.

Is this a high-volume, commercial process? Worldwide, there were more than 45 million magnesium phone housings shipped in 2001. Thixomolding® has been successfully used in many high-volume applications.

What shapes are possible? All shapes possible with plastic injection are available. Additionally, because of the better flow properties of magnesium, rib to wall height can be increased over plastic injection molding. Contact Parkway Products for more details on the enhanced design possibilities of magnesium.

Are organic binders used in the process? No organic binders are used in this process. Thixomolding® is a one-step process that uses 100% metal. Several magnesium alloys are available (AZ91D, AM50A, AM60B). Of note, magnesium is the lightest structure metal.

Is magnesium an exotic material in short supply? No. Magnesium is the 8th most abundant material on earth. Numerous magnesium suppliers around the world extract magnesium from sea water or from ores. There is approximately 1 pound of magnesium in 100 gallons of sea water. Additionally, the price of magnesium is not tied to the price of oil as plastic resins are.

What are the advantages over magnesium die casting? Because the magnesium material is injected as a slurry [rather than from a liquid], Thixomolding® provides better mechanical properties, lower porosity, better surface quality and tighter tolerances. Additionally, thinner sections (down to 0.50 mm [0.020 in]) and more complex geometries (longer rib/wall ratios, longer flow lengths) can be made. Contact Parkway Products for more details on the enhanced design possibilities of magnesium.

What are the advantages over plastic injection molding? Thixomolding® provides better mechanical, thermal and EMI shielding properties than any plastic (filled or unfilled). Additionally, the stiffness of magnesium is over 20 times that of most plastics. The increased stiffness allows for thinner sections and reduced material usage that provides a lower cost solution—with improved performance. The flow properties of magnesium are better than many filled plastics, allowing for more complex designs. Contact Parkway Products for more details on the enhanced design possibilities of magnesium.

Doesn’t magnesium burn? Many people remember watching magnesium burn bright white as part of a high school science demonstration. Molded magnesium parts do not ignite after being exposed to a flame. Compare that to the ignition times of some common plastic and nonflammable plastic. In fact, the ignition temperature of solid magnesium is over 450°C (850°F). The high school demonstration showed the impact of heat on the material form of magnesium. With the proper surface area to volume ratio, almost anything can ignite, burn or explode when exposed to the proper ignition source. Only finely divided magnesium (powder, thin ribbon) can ignite easily.

Doesn’t magnesium explode? Molten magnesium does present an explosion hazard, but the design of the injection mold machine eliminates this hazard. The entire process takes place in a closed system, and operators of the equipment cannot be exposed to molten magnesium. When the customer receives the parts they are solid (never molten), so explosion is not even a remote possibility.

Doesn’t magnesium corrode and fall apart? Some may remember magnesium being used in the 1970s in oil pans and other automotive parts. These parts did have corrosion problems. The alloy used was responsible for the corrosion of these parts. In the last 30 years, there have been great advances in the corrosion resistance of magnesium alloys. Modern magnesium alloys (unfinished) have corrosion resistance 4 times greater than aluminum alloys in salt spray testing. Compare the corrosion of various metals. The corrosion resistance can be further improved with the multitude of surface finishing options available.

What finishing options are available? A wide variety of finishing options are available including painting, powder coating, plating and all the Dow treatments developed for magnesium die casting. The Thixomolding® process offers decreased surface roughness and lower porosity than die casting, further expanding the finishing options available. A wide variety of surface textures are also available, similar to the textures available in injection molded plastics.

What surface finish is available on molded parts? RMS 16.

Is it cost competitive—with all these benefits, it sounds expensive? The versatility and design flexibility of Thixomolding® enables highly complex geometry (with intricate detail and excellent dimensional tolerances), less weight, part consolidation and a low total installed cost. Let us prove it to you. Contact Parkway Products with your specific design challenges and we will provide quotations for your review.