How To Make Lighter and Thinner Magnesium Components?
Magnesium is the lightest structural material offering very good
damping characteristics, weldability and excellent shielding
against electro-magnetic interferance, and is unlimited in
supply. It has been an excellent material for making portable
electronic and telecommunication devices, and automotive and
aerospace equipment such as MD player casings, chassis for cell
phones, video cameras and notebook computers, automotive gear
housings, car wheels and engine blocks.
The most common method to produce magnesium parts is by die
casting and thixomolding processes. However, these runner and
gating processes provide a low material yield of only 30% for
thin-wall casting and can only produce thin walls of between
0.7mm to 1.2mm.
If we can form magnesium parts from sheet metal just like metal
stamping of steel and aluminum parts, we can achieve better
material yield of about 80% and possibly safer operation due to
the lower processing temperature. However, magnesium is known to
be non-formable as it is very resistant to deformation due to
its hexagonal close-packed structure. The only way is warm
forming of magnesium as deformation of magnesium above 225
degrees Celsius will cause additional slip planes to become
operative.
Extensive process research in this area have resulted in a few
warm forming hydraulic presses available in the market for draw
forming. Recently, research in warm draw forming of magnesium to
make cell phone chassis has successfully shown that 0.4mm thin
walls can be achieved consistently. Metallographic tests of the
chassis have also demonstrated that there is zero porosity and
increased rigidity.
While the current warm forming press systems are complicated to
operate as they require the preliminary building of stroke and
force profiles for the specific products using data acquisition
modules and forming simulation softwares, the increased
replacement of aluminum and plastics with magnesium for handheld
electronic devices may well accelerate this process. Progressive
early adopters of this technology would have a first mover
advantage in the competitive global manufacturing industry.