September 17, 2004, 02:35 AM
Would somebody please tell me what MIM means?
September 17, 2004, 04:00 AM
Metal Injection Moulding.
Liquid metal is pumped into a mold under pressure.
September 17, 2004, 04:33 AM
Is that the same thing as cast?
September 17, 2004, 04:49 AM
Cast is usually kinda pour'd in i thought...
i'm sure there is something to the process that strengthens over casting - otherwise it would be cheaper to do w/a casting.
September 17, 2004, 05:19 AM
Nope, no liquid metal is involved.
Metal Injection Molding involves metal powder mixed with a polymer binder, together used to fill a precise mold. The binder is there to 'glue' the metal grains together. You pop the weakly-bonded part out of the mold (thus, the mold can be used again right away), and subject the part to enough controlled heat over time, so that the polymer burns away into nada and the metal grains fuse/sinter together.
Since you're not really 'melting' the metal outright, and the binder loiters a bit, it retains its molded shape throughout, without benefit of a mold. The process eliminates a lot of hassle regarding quantity of molds needed, as well as durability of molds vs. repeated exposure to heat. With precise molds, you can get pretty intricate shapes, with no need for machining afterwrds. MIM parts are thus cheaper to produce, ....and, well, just plain cheaper, hehe.
However, if the powder grains are insufficiently fused you get weak parts. On top of that, even a better-sintered product is still weaker than a well-cast or well-forged equivalent, so MIM replacements for standard forged or cast parts tend to be beefier in proportions to compensate.
September 17, 2004, 05:27 AM
Thanks! Learn something new every day..
was under the impression that MIM was better than cast...
i stand corrected =)
(and no - i didn't look it up... rofl i should have - just assumed since i've seen metal injected molding - as a "feature" that it was something noteworthy... i was wrong :) )
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