Magnesium holds the promise of being the future metal used in almost all cars around the world because of it abundance and properties, but its use has been stymied until now because of the cost involved with making it structurally strong enough to be used in cars and automobiles.
A new process developed at the Department of Energy’s Pacific Northwest National Laboratory could soon do away with the hurdles of mass adoption of magnesium in auto industry. This is because the new method has the potential to reduce cost by eliminating the need for rare-earth elements like dysprosium, praseodymium and ytterbium, while simultaneously improving the material’s structural properties.
The new process effectively brings in a new twist on extrusion, in which the metal is forced through a tool to create a certain shape, kind of like dough pushed through a pasta maker results in different shapes.
According to theory, if magnesium alloy is spun during the extrusion process it would create just enough heat to soften the material so it could be easily pressed through a die to create tubes, rods and channels. Heat generated from mechanical friction deforming the metal, provides all of the heat necessary for the process, eliminating the need for power hungry resistance heaters used in traditional extrusion presses.
Implementing their ideal, the team developed one of a kind Shear Assisted Processing and Extrusion machine — coining the acronym for ShAPE™ that allowed them to extrude very thin-walled round tubing, up to two inches in diameter, from magnesium-aluminum-zinc alloys AZ91 and ZK60A, improving their mechanical properties in the process.
The billets or chunks of bulk magnesium alloys flow through the die in a very soft state, thanks to the simultaneous linear and rotational forces of the ShAPE™ machine. This means only one tenth of the force is needed to push the material through a die compared to conventional extrusion.
This significant reduction in force would enable substantially smaller production machinery, thus lowering capital expenditures and operations costs for industry adopting this patent pending process. The force is so low, that the amount of electricity used to make a one-foot length of two-inch diameter tubing is about the same as it takes to run a residential kitchen oven for just 60 seconds.
Energy is saved since the heat generated at the billet/die interface is the only process heat required to soften the magnesium.