When did gun makers start using metal injection molding? (MIM)

[WonderNine]

Just curious, when gun makers started using it. And also...who was the first? Not that that matters much, but would be interesting to know.

I've pretty much sworn off most new guns because of MIM'd parts. Strangly all the lemons I've owned were recently manufactored guns and all the best of the best I've owned were made before I was born or when I was a toddler.

I hope this turns out to be an informative thread without "too much" name calling...

Comments?

 

[RON in PA]

Don't know the first use in the firearms industry, but know that S&W started using MIM parts in 1998-1999.

 

[ponyexpress]

Anybody know how you identify MIM parts? Would they show some sort of seam or is this something you need to find out from the manufacturer?

 

[MoNsTeR]

Many have seams, but almost all have a sprue mark at the place in the mold where the material was injected. It'll be a small indented circle, with a diameter usually about equal to the height of a letter on a .45 heatstamp. On larger parts like grip safeties, the sprue mark can be larger, more like a small primer.

 

[4v50 Gary]

The first run of Colt Troopers (MK III, new action that was apart from the Python action of the earlier Trooper) had MIM internal parts (and yes, they fell apart). BTW, the quality of MIM has improved dramatically since then.

 

[Master Blaster]

I have read all of the HOO HAA about mim parts.

I own about 20 carbide tipped router bits they are 100% mim, sinterred metal. they spin at 20,000 rpm and they cut wood, and even sometimes nails. I have been using these bits for 10 years now on a frequent basis.

None of them have ever failed.

Now I used to have machined tool steel router bits, machined from a solid bar stock, guess what they used to chip and dull very quickly. I even had one break off at the shaft when I hit a nail in some recycled wood.


Other things made of mim, jet aircraft engines, rotors on turbines.

All are high stress applications where machined steel used to fail.

MIM can be very consistant and very reliable, and even better than machined tool steel.

It depends on the formulation of the mim, the manufacturing QC, and the application.

Gun parts are much lower stress applications than the ones I mentioned above.

So far I have had no problems with MIM parts in my guns.

 

[telewinz]

I thought Ruger was the leader.

 

[bountyhunter]

I've pretty much sworn off most new guns because of MIM'd parts.

MIM is not the problem, merely a manufacturing method which is very viable for making specific types of parts when the process is properly controlled. The problem with new guns is that gun makers conducted a grand experiment on us where they decided QA was too expensive and unnecessary if they just throw a blanket "lifetime warranty" over everything and let us find the clunkers. I guess their experiment worked, people are buying more guns than ever and companies like SW and Kimber ship crap, even out of the once renouned Performance Center at SW which used to be known for making guns of near custom fit and finish. Now they are the same crappy junk as their production guns, and the defects I find looking at their new guns would fill an encyclopedia.

 

[bountyhunter]

Many have seams, but almost all have a sprue mark at the place in the mold where the material was injected.

You will generally be able to find two "hole" outlines in an MIM part, one where the material is injected into the mold and the other for the air to escape.

 

[4v50 Gary]

Naw, Ruger casts theirs and instead of shooting powder metal into a mold, Ruger pours molten metal into the mold.

 

[Dorrin79]

Ruger uses something called "investment casting" that they are apparently the experts on.

Whatever it is, it must work pretty well, as their P-series autoloaders (which are cast) are basically indestructible.

 

[Tropical Z]

Whats the difference between MIM and investment casting?

 

[LoneStranger]

Trppical Z, not being an expert or even one very experienced with some of this stuff but just putting together some related info.

Investment casting is where they actually make a separate casting mold for every part cast. Then the mold is destroyed when you remove the part.

MIM is where you make a die mold which is used to make multiple quanities of the particular part. What they do is inject the metal in the die then when it gets solid they drop out the part and start the cycle over.

Beyond this you will need to consult with someone who can count past 12 without taking off their shoes.

 

[4v50 Gary]

With investment casting, a wax model of the object desired to be casted is made and dipped into a sand & slurry mixture until a heavy, durable mold is built up. Said mold is then fired to (1) melt the wax and (2) heat the mold to receive the metal. Molten metal is then poured into the mold and allowed to cool. When the metal is cool enough, the mold is broken, the object is cut/machined/ground to spec.

With MIM, powdered metal (solid, non liquid) is injected into the mold. It is then heated to bind the powdered metal together. With the early Colt MK III Troopers, the MIM/sintered metal process resulted only in a surface hardness and once the surface wore, the part fell apart. Colt has corrected the process (I think they use castings for some internals and someone, please correct me if I'm wrong).

 

[caseydog]

To add to what lone stranger said , typically investment casting requires casting slightly oversize and minor machining to bring the part into tolerance , where a MIM part will typically drop out about perfect , very uniform process. The quality is in the quality of the die and the metal alloy injected, if you have those 2 worked out MIM can result in very high quality well fitting parts. Case

Edited to add : Gary ,the most current MIM process uses a polymer binder with the sintered metal , the polymer liquid / metal mix gives a more uniform injection than dry powdered metal , the polymer then burns off with the heating of the mold.

 

[tiberius]

There's nothing wrong with MIM if it is done right and the parts are designed to take advantage of its properties.

 

[4v50 Gary]

Why, thank you Caseydog. I wasn't aware of the polymer's use as a binding material.