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ThixoForming: The Many Uses of Mighty Magnesium
Product designers have become increasingly successful in harnessing
magnesium's more desirable metallic properties, especially strength
in applications where lightness and rigidity are also desired.
One of the frontiers for these new developments has been thixomolding,
or semi-solid molding as it's sometimes called. The name is derived
from the thixotropic region of a phase diagram. While a phase diagram illustrates
the entire spectrum of a material's potential behavior, the thixotropic
region of the diagram refers only to the phase during which a material teeters
on the border between behaving like a solid or a liquid.
When magnesium is mixed with aluminum, the resulting alloy
attains an unusually wide thixotropic phase of about 150°. This makes
the alloy easier to work with, allowing it to be slowly poured with molasses-like
consistency into plastic-injection molding machines without the turbulent
flow fronts that often accompany standard die-casting processes. Turbulent
fronts, which occur when solutions are poured into molds under high pressure,
are more likely to trap gasses that can lower product density.
The thixomolding process employed by AFT, trademarked as ThixoForming™,
is unique in that it uses precision parts instead of machinery, which is
more likely to malfunction. The process is also more environmentally friendly
because it does not require the non-oxidizing, ozone-depleting FSX gas used
in traditional magnesium die-casting.
With these advantages, thixomolded applications are gaining
enthusiastic acceptance throughout several industries. The electronics, telecommunications,
and computer industries, for example, are increasingly incorporating thixomolded
parts in their products. These industries especially prize:
- High stiffness of magnesium compared to plastics, allowing for thinner
walls and tighter tolerances in precision products such as cameras and
power hand tools.
- High density yields superior EMI/RFI shielding without the need for extra
components or expensive coatings. This reduces the cost of products such
as phones, e-mail devices, radios, and other products that need shielding
from electromagnetic and radio frequency interference.
- High thermal conductivity compared to plastics, allowing the use of lightweight
parts in products that develop high-temperatures such as projectors.
- Consistent, highly accurate dimensional stability, which permits high-volume
duplication of intricately shaped designs while eliminating costly machining.
Companies in the medical, automotive, and fluid power industries
are also partnering with AFT to apply ThixoForming™ to their products.
Combining the best of plastic injection molding with traditional die casting
technologies, ThixoForming is the bright, new future of magnesium. For
additional information on ThixoForming™, visit www.pcc-aft.com or
call 303-833-6000. |
