MIM Technology – Is It Right
For Your Job?
Metal injection molding combines the shape making capability of plastic
injection molding with the material flexibility of powder metallurgy. MIM
technology takes advantage of unique process capabilities such as combining
components into one complex co-molding and bonding dissimilar materials. MIM
is well suited for the manufacture of relatively small, complex components
that require high strength and cost viability.
The Process
The MIM process involves six steps: design, mold making, compounding, molding,
debinding and sinter. Here's how it works, in the design phase
engineers utilize computer aided design technology to prepare customer's
concepts and make the mold. During compounding, fine metal powders,
thermoplastics, and other proprietary ingredients are mixed to form a pelletized
molding compound at a typical volume ratio of 60% metal to 40% binder. Conventional
injection molding machines are used to mold green parts during the actual
molding process. Using heat, solvents or a combination of the two,
the binding material is removed during debinding. The brown parts are
sintered in vacuum type furnaces during the final phase of the MIM process.
Advantages
MIM has many advantages over other forming processes. Its application
for complex parts, high volume and a variety of materials is superior to
other methods such as die cast and screw machine. Typical densities
for MIM range from 95% - 99%, which yield properties close to cast or wrought
products. MIM Components range in size from 0.1 grams to over 150 grams
in weight.
Mold construction may consist of either single or multiple cavities depending
upon the estimated annual volume. In most cases, quantities average
20,000 pieces per year minimum. Alloy and stainless steels, along with
other non-ferrous alloys, such as titanium, are common materials for MIM.
Common MIM Questions
Q: WHAT'S AN AVERAGE TOOLING COST?
A: Generally, a typical 2 - 4 cavity tool costs between $15 - $35,000, which
is similar to production plastic injection molding tools. AFT is the most
competitive on small parts where the material cost becomes less of an issue,
and on larger parts where we get enough value through intricate detail to
off set material costs.
Q: WHAT IS THE PRODUCTION CAPACITY FOR A TOOL?
A: 500,000/parts/year/cavity.
Q: WHAT ARE YOUR BEST MATERIALS USED?
A: Stainless Steels plus other Ferrous alloys. MIM process is not recommended
for aluminum and magnesium, but we are now working with titanium.
Q: WHAT TOLERANCES CAN BE HELD?
A: .003" to .005" per inch. Part features must be considered and
secondaries are often used to decrease tolerance.
For more information on the MIM process, visit the Resource Library section
of our website at http://www.pcc-aft.com/library/library.html or
contact our experienced MIM sales and engineering staff at http://www.pcc-aft.com/contact/contact3.html or
303-833-6000. |
