Today, magnesium alloys can be found and used in ways that could not be found in the heyday of metal in the 1950s. In fact, the magnesium alloys used today have the added advantage of being respectful with the environment. With the abundance of literature available on the Thixomolding process that has revolutionized magnesium alloy manufacturing today, it is difficult to determine if the process is overdone or really worth considering. Here are four things to remember when analyzing Thixomolding.

1. It is injection molding and not true casting.

Thixomolding involves heating magnesium alloys to very high temperatures, but the heat does not reach the melting point of the metal. The goal is to bring the metal granules inserted into the heated chamber of the Thixomolding machine to a state that is somewhere between liquid and solid. An alternate screw in the middle of the grout is part of the Thixomolding technology. The mixing / shearing action is what helps to achieve the proper consistency needed for the molding part of the process. Once it reaches a desired state, the metal is injected into the mold. Therefore, unlike cast iron, Thixomolding does not involve the high heat and long cooling time.

2. The process does not produce emissions.

In magnesium metal smelting, the metal is heated to temperatures that are high enough to start the oxidation process and cause the mother liquor to ignite. To avoid this, foundries “cover” the metal with a gas made of sulfur hexafluoride. The gas is released into the air, causing the plant’s emissions to skyrocket. In Thixomolding, magnesium never reaches critical temperatures, so gas is not necessary. The low heat required to create the grout is also an energy saving factor.

3. The metal walls of the created products may be thinner than the plastic ones.

The magnesium alloy produced through Thixomolding is thinner than the cast version, but still very strong. Injection molding simply allows for greater versatility in the parts that the magnesium alloy can form.

4. Thixomolding has a recent popularity, but a history of research and development before hitting the market.

Japan Steel Works LTD. Describe the history of the thixomolding process.

• The process began in 1971, with the discovery that a metal can be brought to a semi-liquid state while remaining fluid enough to be molded. Mixing or stirring was the key to the process called Thixomolding at the time. The remainder of the 1970s was spent exploring the process and its ramifications in the metal molding process. The granules were found to work better.
• Screw mixing / shearing technique was added in the 1980s. The researchers found that the metal remains semi-solid while stirred. Upon stopping, the alloy solidified. At that time, they also discovered that they could mold metal like plastics, very thin and almost in shape and size, without compromising the integrity of the metal.
• Injection molding was added in the 1990s. The process is used today to create housings for electronics, medical implants, panels, and more.

Thixomolding is expanding in the ways manufacturers are implementing the process in their product development. It is slowly replacing the reliable, but bulky and heavy metals like steel. Magnesium alloy is already the standard in personal electronics manufacturing.