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Many Industries Are Warming Up To Metal Injection Molding
Metal Injection Molding (MIM) is hot.
While the technology is not necessarily new, having been commercially available
for almost 20 years, metal injection molding is growing increasingly popular
with a gamut of industries. In particular, medical device, telecommunications,
electronics and automotive parts manufacturers have turned to MIM as a viable
and cost-effective alternative to other types of metal processes, such as machining
and casting. The driving force behind MIM's rise in popularity is that the
process is well suited for the high-volume manufacture of relatively small,
complex components requiring high strength, high performance and cost efficiency.
MIM Technology Offers Flexibility
Metal Injection Molding combines the shape making capabilities of plastic
injection molding with the material flexibility of powder metallurgy. The
basic process uses pressure and heat to form precision metal parts and shapes.
Using fine metal powders in combination with a thermoplastic binder, the mixture
is heated and injected into a mold. When ejected from the mold, the resulting "green
part" is typically 15-to-25% larger than the finished product. It is
then exposed to heat, solvents or a combination thereof to remove the binder
material, leaving a part comprised of microscopic lattice-work metal.
This part is finally passed through a sintering furnace, which fuses and shrinks
the metal, creating a high-density, complex and precisely shaped part that
exhibits properties approaching that of wrought material. Alloys and stainless
steels, along with other non-ferrous alloys such as Titanium, are common materials
used in MIM.
Advantages Over Conventional Metal-Forming Processes
"MIM is attractive because it produces consistent, complex-geometry components
for high-volume, high-strength and high-performance applications," AFT's Andrew Hanson, Vice President of Sales and Marketing, told Modern Plastics magazine
in August of last year. Automation coupled with microprocessor process controls
allow for the production of custom-engineered parts in large quantities while
maintaining consistent quality control.
MIM is economically attractive to manufacturers, as well — especially
against parts that require machining. Machined parts require a considerable
amount of labor and a lot of material is lost during the process. When parts
are molded in mass quantities, MIM-type parts can offer substantial savings.
Furthermore, the more complex the part, the more cost reduction the customer
can realize. Its unique process capabilities also allow for advanced fabrications
such as combining components into one complex geometry or co-molding and bonding
dissimilar materials — capabilities that machining and even die-casting
cannot match.
Used to produce intricate parts as small as 5 mm in diameter as well as larger
components, MIM's flexibility
in a variety of applications — as well as cost viability — will
most likely continue to drive its continued growth in the market. Furthermore,
new developments and capabilities, such as three-dimensional shape making with
material properties similar to conventional powder metallurgy, will only help
to expand MIM's applications in more industries across the board.
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