Magnesium alloys today can be found and used in ways that they could not in the metal’s heyday in the 1950’s. In fact, the magnesium alloys used today have the added advantage of being environmentally friendly. With the abundance of literature available on the Thixomolding process that has revolutionized magnesium alloy manufacturing today, it is hard to determine if the process is hype or actually worth the consideration. Here are four things that you should remember when looking into Thixomolding.
1. It is injection molding and not true casting.
Thixomolding does involve heating the magnesium alloys to very high temperatures, but the heat does not reach the metal’s melting point. 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. A reciprocating screw in the midst of the slurry is part of the Thixomolding technology. The mixing/shearing action is what helps reach the proper consistency needed for the molding part of the process. One it reaches a desired state, the metal is injected into the mold. So, unlike casting, Thixomolding doesn’t involve the high heat or the lengthy cooling time.
2. The process produces no emissions.
In magnesium metal casting, the metal is heated to temperatures that are high enough to initiate the oxidation process and cause the mother liquid to ignite. To prevent this, foundries “cover” the metal with a gas made of sulfur hexafluoride. The gas is released into the air, making the plant’s emissions output skyrocket. In Thixomolding, the magnesium never reaches the critical temperatures, so the gas isn’t needed. The low heat needed to create the slurry is an energy saving factor as well.
3. The metal walls of products created can be thinner than plastic.
The magnesium alloy produced via Thixomolding is thinner than the casted version, but is still very strong. The injection molding simply allows more versatility in the parts that the magnesium alloy can form.
4. Thixomolding has recent popularity, but a track record in research and development before it hit the market.
Japan Steel Works LTD. Describes the history of the thixomolding process.
- The process began in 1971, with the discovery that a metal can be brought to the state of semi-liquid while remaining fluid enough to mold. Mixing or stirring was the key to the process named Thixomolding at the time. The rest of the 1970’s was spent exploring the process and its ramifications on the metal molding process. It was discovered that granules worked best.
- In the 1980’s the screw shearing/mixing technique was added. Researchers found that the metal remain semi-solid as long as it was agitated. Upon standing still, the alloy solidified. At that time, they also discovered that they could mold the metal like plastics-very thin and in almost in shape and size-without compromising the metal’s integrity.
- Injection molding was added in the 1990’s. The process is used today to create housings for electronics, medical implants, panels, etc.
Thixomolding is widening in the ways that manufacturers are implementing the process into their product development. It is slowly replacing the trusted, but bulky and heavy metals like steel. Magnesium alloy is already the norm in personal electronics manufacturing.