MIM vs. Machined

Aren't most OEM pistons, crank shafts, and connecting rod's for engines MIM?
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No, they are typically castings. Those parts are all too large for MIM.


Chances are, custom gunsmiths don't use them...
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I doubt any would. Not when they can produce higher quality parts from barstock using mills and EDM's. David Clements produces hammers, triggers and barrels rather rapidly (compared to mechanical machining) with his wire-cut EDM machine. Gunsmiths have no need to produce thousands of parts at a time. MIM is best suited for mass production.
 
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I think it is necessary to recognize that MIM bashing is simply another angle of attack for the S&W haters. Other companies use MIM, but S&W has done so pretty successfully, so it must be something evil because to the haters what is wrong is not MIM, it is the continued existence of S&W.

Jim
 
My experience with MIM parts is in the "new" 1917 S&W revolvers.

The gun functions fine, but, when I took the side plate off to do a detail cleaning, I could see that they look like cheap cast pot metal parts.

So I guess my only gripe is their cheesy appearance.
 
Now, we have metal injection molding... I have seen parts made this way that conventional machining could never do, or it would be so cost prohibitive. MIM is an advanced technology that keeps getting better as time goes. These MIM parts are used in aeroplanes and advanced fighter jets. Why wouldnt they work in a firearm?
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I worked as a helicopter mechanic, for 6 years.

The problem with MIM is not the process. The process is very sound, and proven. The problem is the manufacturer. When companies (or governments) buy from the lowest bidder; sometimes they get the lowest quality.

Low bidders love providing their contractors with bubble-laden parts. Every MIM failure I have seen was caused by bubbles.

We had a series of engine failures on our helicopters. In the end, all the problems were traced back to a valve with a MIM shuttle piston (shifts back and forth to direct air flow). Our wonderful supplier had such horrible quality control, that every piece we had was riddled with air pockets. We had to force an 'emergency' purchase of new valves, from a new supplier, while we filed the paperwork to void the existing contract.

The new supplier's parts never suffered a failure.


When the failure of a MIM part is blamed on the process, it tends to get shouted from the proverbial roof tops. Rather than pointing out poor quality control; most people blame the technology as a whole. (Not knowing that their other weapons have had MIM parts for many years...)
 
CraigC:

No, they are typically castings. Those parts are all too large for MIM.
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MIM is not cast metal?

TBS, those piston's and crank's go through much more pressures (At least I think) than most gun parts, but I might be wrong.:D

PS, have you ever heard of vacuum casting?
 
Our wonderful supplier had such horrible quality control, that every piece we had was riddled with air pockets
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If a gun cumpany can save money by riddling a part with pockets, It will do so. It shouldnt be that way but it is.

MIM is not cast metal?
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Ive wondered what would happen if I called MIM parts "castings." I think they are castings but I suspectg a great many peoplw would gert real mad if I called them that.
 
...it must be something evil because to the haters what is wrong is not MIM, it is the continued existence of S&W.
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Not really, not for me anyway. I don't hate S&W nor do I hold the Clinton agreement against them. It ain't the same company. I love S&W's and wish I could have the same feelings for the new ones as I do for the old ones. I just don't. The internal locks, the injection molded parts, the two-piece barrels and the inflated prices. They just don't appeal to me anymore. Not at their price point. Might have something to do with paying $265 for a bright blued 6" K-22 about ten years ago. The new "Classic" is FOUR TIMES as much. I wish them success but at present my money's too good for `em.


MIM is not cast metal?
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No, it's injection molded powdered metal. It never gets hot enough to actually melt.
 
Well said CraigC. I agree. I love my S&W's, all produced prior to 2001.

Some folks are evidently blinded by brand loyalty. Regards 18DAI.
 
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MIM is not cast metal?
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Casting involves melting metal and then putting it in a mold.

MIM is a sintering process.

Metal powder is formed to the desired shape, then the object is heated to below the melting point of the metal to make the powder particles stick to each other.

There are some things that are only made this way (carbide tooling), and other items like gun parts that can be made other ways but MIM lowers manufacturing costs in high volume applications.


Poor quality casting can have voids.
Vacuum degassing was developed to eliminate voids in casting.

Even forged parts can end up with weak spots of there are excessive or large voids in the starting material.
Forging can close up voids, but the boundary created in the forging is often still weaker than the rest of the material.
 
Two questions: Could it be that the problem with parts that people experiencing failure with MIM parts are experiencing problems due to those parts not being designed to be made from MIM?
Can MIM be drop forged?
 
In its childhood I wouldn't have trust MIM. The MIM process was invented in 1973 by Karl Zueger, but was not adopted for manufacturing use until the 1980s. Kimber uses MIM parts, Wilson uses some MIM parts. Would I rather have machined versus MIM if given a choice for the same cost? Yes. Have I ever not purchased something because it contained MIM parts? No.

I think the process of MIM, when done right is very solid. Like anything else I'm sure there's an outsourcing company somewhere that makes MIM products of low quality as the lowest bidder. Just like there's bad machining work out there too.

http://www.flomet.com/MIM.asp

I'm not trying to offend the OP here. MIM threads have become about as common as Glock versus XD and 45 versus 9MM threads. Every company has, at some point made a lemon and usually on the internet that one lemon is turned into 1000 lemons.
 
Can MIM be drop forged?
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MIM parts come out nearly at final dimension and finish.

Precision holes may need reaming, but most surfaces barely need any cleaning up.

Drop forging would not do much to improve the part.

Drop forging works best on metals heated to a plastic state, allowing the metal to flow under the pressure of the forging hammer.
 
I got "epifinized" in the last thread about MIM. I am forced to conclude that it has less to do with brand hate than with understandable intellectual inertia. Once a conclusion is reached or an opinion formed it tends to remain in place.

And it seems few folks, apart from the aerospace posters here, realize that MIM technology is both relatively new and changing. Since it's a metal forming process the tendency of gun folks generally is to view it in the same light as some other metal forming techniques and assume it's relatively static.

I actually had one poster back up his MIM concerns by citing an article from 1990. I was flabbergasted. Then comes the epiphany - why wouldn't he think stuff from 1990 was still valid?

Fact is though that MIM tech from 1990 is about as current as semiconductor tech from 2000.

Kimber gets the lion's share of MIM distrust (IMHO, justifiably so) in semi autos and S&W seems to have inherited it in revolvers.

I would concede that a parts failure from 1990 is viewed as quite relevant today. I would, however, be curious as to how many have been reported with current product.

The S&W Performance Center actually boasts that there are "Forged parts only" in their pistols. Wonder why they do that? Given the obvious superiority of MIM as told to us by experts here, why not put MIM parts in those expensive PC pistols and revolvers?
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I sometimes bring needless grief on myself by attempting to answer questions which are obviously intended to be rhetorical but I'm feeling froggy.

I suggest it may well be to allow the use of the pinned double action sear. The MIM parts use an interlocking arrangement and the pinned sear is easier (hence cheaper) to tune. In other words, forged is the cheaper alternative if a pinned low-volume part is a priority. The PC volume is insufficient to justify a MIM part.
 
I am forced to conclude that it has less to do with brand hate than with understandable intellectual inertia.
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"Intellectual inertia". Wow.

I call it skepticism through experience. Fire forged and tempered by the school of hard knocks. Did I mention that I had TWO failures of MIM parts in two separate Kimbers?
 
I call it skepticism through experience. Fire forged and tempered by the school of hard knocks. Did I mention that I had TWO failures of MIM parts in two separate Kimbers?
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So did I - a shattered ambi safety and type 2 plunger.

Difference is, I blame Kimber's sorry implementation and not the process.

One man's intellectual inertia is another's experience. It'd be boring if we all agreed, would it not?
 
brickeyee

Poor quality casting can have voids.
Vacuum degassing was developed to eliminate voids in casting.
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Not to go to far from MIM vs forge.

I just remember Yamaha used this process to form there (2000ish) Snowmobile (First modern four stroked snowmobile), and sport bike frames and got the same rigidity with half the metel/weight.
 
And the difference is what exactly?
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The differences are both numerous and profound.

By all indications the dark times have ended for our friends in Yonkers and I choose not to pick at the scab. This isn't a Kimber bashing thread.

Do a search, you'll be enlightened. There was a time when they could have screwed up a rubber anvil and blamed it on lack of break-in.

Bagging on MIM because of Kimber is understandable - particularly for those of us that experienced it first hand. However, it's about as valid as bagging on cast aluminum in engine blocks because Buick division messed it up in '61. Folks cheerfully pay extra to get it now.

The world has moved on. Firearms enthusiasts are generally a traditional and conservative lot - no law states they have to move on as well. I do find it mildly ironic that many use 21st century computers and technology that was considered science fiction in 1970 to express opinions that were formed before there was such a thing as an internet forum to allow such.

Stay well clear of many auto manufacturer's top of the line offerings: those aluminum engine blocks will leave you stranded in a heartbeat.
;)
 
Numerous and profound? Seems to me if Kimber chooses not to QC their parts, which in my case its obvious they do not, then there really is not much difference between the Kimber's processes or implementation. Because, in the end, I paid too much of a high price for a sub-par gun.
 
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