What is it ??

[Jack Stanley]

I remember a thread we had a while back about handguns we'd like to see . Several times when S&Ws were mentioned MIM parts were given a negitive review . I'll admit being behind the times , would someone explain what MIM is ?

Thanks , Jack

[Von Dingo]

Metal injection molding. Parts dropped from the machine almost ready for assembly.

[44man]

I don't know why, they are as strong or stronger then forgings. The steels we have today do not need beat to shape.

[btroj]

They are a great way to start a heated discussion too!

[Hawken]

This is from wikipedia, but it is a pretty good description. The problem some of us have with it, is that you can get a void, and you will not know it until the part breaks, and it could happen in one round, or a thousand rounds, and working the component can be problematic.

Metal injection molding (MIM) is a metalworking process where finely-powdered metal is mixed with a measured amount of binder material to comprise a 'feedstock' capable of being handled by plastic processing equipment through a process known as injection mold forming. The molding process allows complex parts to be shaped in a single operation and in high volume. End products are commonly component items used in various industries and applications.

The nature of MIM feedstock flow is defined by a physics called rheology.[1] Current equipment capability requires processing to stay limited to products that can be molded using typical volumes of 100 grams or less per "shot" into the mold. Rheology does allow this "shot" to be distributed into multiple cavities, thus becoming cost-effective for small, intricate, high-volume products which would otherwise be quite expensive to produce by alternate or classic methods.

The variety of metals capable of implementation within MIM feedstock are referred to as powder metallurgy, and these contain the same alloying constituents found in industry standards for common and exotic metal applications. Subsequent conditioning operations are performed on the molded shape, where the binder material is removed and the metal particles are coalesced into the desired state for the metal alloy.

http://en.wikipedia.org/wiki/Metal_injection_molding

[Jack Stanley]

Thanks guys , it all sounds very much like the work I used to do many years ago with magnesium and aluminum with cold chamber injection machinery ( ran a hot chamber machine but that's a story by itself )

Am I correct they are using non-ferrous metals for this process ?

Jack

[NoZombies]

Most MIM parts that are found in guns are steel alloys. By definition, they will be slightly less dense than a drop forged part.