MIM Parts

MIM Making Imitation Metal, sorry had to say it. I have no problem with MIM done right. Castings and forgings have a failure rate also, nothing is perfect but some processes and materials are better than others for certain applications, and most are fine when used in the proper application.
 
I am an engineering manager for a contract manufacturer. Our core is Swiss turning and miniature precision machining but as our work in medical has expanded we have become more and more involved in MIM.

MIM has it's place. For us and our customers looking for surgical device components a main limitation is the inability to detect an internal flaw in a finished part. That is less and less of a problem as processes improve but the bottom line is if you need to be 100% certain it is solid material you can't depend on MIM. It will be better than 1 ppk. It may exceed Six Sigma. The problem is there are times when 1 in a million is still too many. Generally firearms are nowhere near that quality level given the vast majority of their usage is at a time where a failure will not kill someone.
 
Do I think MIM is the spawn of satin? No.

Are there OK MIM parts --- sure how about cylinder latches and sights?

But given modern methods that CAN make parts out of solid bar stock, reasonably, why go MIM?

Oh that's right, profit for the maker, no reason with the price they charge that the critical parts of many guns can be a MIM free zone, but alas it's not so, so we either replace the parts or live with it.
 
For us and our customers looking for surgical device components a main limitation is the inability to detect an internal flaw in a finished part.
Click to expand...

X-ray inspection is simple and will easily real any voids in a MIM part, just like in a cast part.

You do not need actual x-ray film unless you need to keep permanent records.
A fluoroscope is more than adequate, and many of them can frame grab from the video camera aimed at the fluoroscope screen.

Take two orthogonal looks and you can even find the location of voids very easily.
 
I think for some it is less an actual part reliability or integrity issue and more an issue of old world craftsmanship making way for newer, more efficient, and less costly machine made parts. Not as much hand fitting and the like. Good thing too because without MIM guns would be more expensive and possibly even prohibitively expensive.

Be that as it may I still only buy older Smith and Wesson revovlers and will not touch anything from the post lock years. Just the principle and I have witnessed one fail.
 
MIM has its place in the industry. There are pros and cons to it. Its just some people want to feel secure with knowing that they have a "old time and proved" billet part that might not have to be made in billet. But it makes them feel better.
 
Profit for the maker? That sounds like the old leftwing BS about how we need to tax companies rather than "the people", hoping the suckers don't know that companies pass their costs (including taxes) on to "the people".

I have talked to some pretty savvy folks about making guns "the old fashioned way" with all forged and milled parts and hand fitting. The answer is that a gun (or anything else) made that way would cost from 7 to 20 times what it does now. There are applications not suitable for MIM parts, the same as there are applications not suitable for parts made other ways, but MIM produces "drop in" parts that can be top quality.

Anyone who knows S&W revolvers can easily examine the lockwork of a new revolver and compare it to one made in, say, 1920. The savings in machine time, hand assembly, and complexity is tremendous.

Take one part, the trigger.

In a 1920 S&W, the trigger had a hand lever, a tiny pivot pin for the hand lever, a hand lever spring, a trigger lever and another tiny pin for the trigger lever. The holes for the pins had to be drilled, and the hole for the hand lever spring had to be drilled, and the small parts had to be made. This is all in addition to the holes for the hand and the hand itself.

The MIM trigger still has holes for the hand, but two small holes and five small and hard to make parts have been eliminated, replaced by one wire spring. Assembly, which required hand fitting of all those parts now involves placing that one spring in a hole that is not drilled, but made into the MIM part. The trigger lever is still needed but has no pin and is a much simpler part. Still want stuff made the old way? Willing to pay $2500 for that Model 642?

Oh, and want to trade your 2009 car for a Model T? Anyone remember the three pedals and the throttle on the steering wheel? And having to back up hill?

Jim
 
Oh, and want to trade your 2009 car for a Model T? Anyone remember the three pedals and the throttle on the steering wheel? And having to back up hill?
Click to expand...

And the mechanical brakes (push rods & bell crank style).
 
There have been some really good posts in this thread and, as I initially suspected, the controversy centers around the old "...they don't make 'em like they used to" gripe.

I have yet to have any problems with my investment cast Colt Government Models, Rugers, S&W autos, or with my post '64 Winchester 94 with stamped parts. Some folks just don't like change, I guess.

At any rate, time will tell...
 
My biggest gripe with investment cast and MIM is in the finishing. To me, crappy finishing is a sign that they didn't put the effort that is needed to make the investment cast or MIM part stronger than a well machined forged part. If its well finished, with attention to detail, and has a reputation of being rugged and reliable (can't actually inspect structural integrity for myself), then I'm ok with the use of newer technology in forming the metal parts of guns.
 
Is there any significant difference between MIM and Sintered parts.
Seems that both processes, correctly done could produce very good parts.
 
Well, I can now say, after opening up the Model 22 .45 ACP 1917 "replica" that I bought a few months ago, that I am thankful I haven't bought any more post lock S&W revolvers. The MIM parts may turn out to be 100% serviceable, but they look for all the world like cast ZAMAK parts.:barf: I was NOT impressed, nor do I see any good way to "convert" back to older style parts, at least not the hammer, anyway. (Don't think any previous "N" frame gun had a frame mounted firing pin.)

In all likelihood, since this gun will not get a lot of hard use, it will be just fine, but time will tell.
 
ZAMAK Strength

Eastern Alloys claims that its ZAMAK-27 (73% Zinc, 27% Aluminium) is STRONGER than Steel!! (http://www.eazall.com/casehistories.aspx#sa under heading Zinc Alloys vs Steel Alloys).

It is understood that Hi-Point and Walther P22 slides are made of ZAMAK-3. Can anyone quote the 'official' (company) source which says that the slides are made of this material? Could it not be ZAMAK-27?
 
I have yet to have any problems with my investment cast Colt Government Models
Click to expand...

Where were you able to get one of those? :confused: All Colt frames and slides are machined forgings, and always have been. 1st three Gens of S&W autos, too. Rugers are generally engineered to be made via investment casting, so a cast Ruger is not a "replica" of the real thing, as is the case with the Colt or Smith.
 
You must log in or register to reply here.
Back
Top