MIM vs. Machined

[jhgreasemonkey]

From what I understand just about every manufacturer of production line firearms uses at least some mim parts now.

 

[cougar gt-e]

A little OT, but "newer calibres" don't offer a whole lot that hasn't been done many, many times before. In fact, after the advent of the .357 Magnum, there has not been any new calibre introduced that has had any widespread practical application whatsoever.

You never heard of the .40s&w or maybe the .357sig>?

Both are widespread here in the USA.

I think the .40 has a contract for delivery of 200 million bullets over the next 5 years to the government homeland security department and 100 million bullets to the FBI.

300 million bullets in 5 years, that's fairly "widespread" .

 

[gyvel]

You never heard of the .40s&w or maybe the .357sig>?

Both are widespread here in the USA.

Yes, I have heard of them both. I have also heard of the 17 WMR, the .32 H&R Magnum, the 9mm Federal, 9x23, .45 Magnum, etc., etc.

They enjoy a brief rise in popularity, then fade into obscurity, because they are specialty cartridges for specialty weapons.

To be honest, I'm not sure there's a whole lot of difference between the .40 S&W and the 9.8mm Colt that was introduced in the early part of the 20th century. The .40 came to be because of the "difficulties" with the 10mm cartridge. To be honest, the .40 doesn't do anything better than the .45 does in the real world. It might have a longer lifespan than others because of the government's involvement with it, however. At least, for the time being, anyway, the .40 ammo is fairly easy to get.

.357 SIG is another upstart that will have a meteoritic rise in popularity, then fade into the third world of cartridges, as it, too, offers no real advantage over other older well established calibres.

 

[JohnKSa]

Yes, but what does educating myself on the parts they're built with do for me? They all come from the same manufacturers. In aircraft, maintenance is the single most important factor. I'm unsure what you're trying to accomplish with this far-reaching analogy. We can revisit this when I become an eccentric millionaire and aircraft enthusiast. Right now it's a little out of radar range.

Missing the point.

The first direct point is that MIM parts are currently being used in applications where failure is absolutely unthinkable. In applications where failures mean massive loss of life and huge liability. If MIM could not be implemented in such a way as to insure reliability then other manufacturing techniques would be employed. You can't justify saving a few cents on a part if it costs a few hundred lives and millions in settlements.

The second direct point is that assuming that you use air transportation you are currently trusting your life to MIM parts. If you truly believe that MIM parts can not be implemented in such a way as to insure reliability then you should stop using air transportation.

The indirect point is that MIM done well is just as reliable/durable as forgings done well. Either of them done badly is prone to early failure. The proper process is FAR more important than the specific technique employed.

Someone on another forum asked a question about which rifling technique (button/cut/hammer forged) was superior. The answer is that what matters is whether the maker implements his specific technique properly and takes the time to check the finished result to insure quality. I'd take a barrel made from any of those techniques as long as it came from a manufacturer with a reputation for making accurate, trouble free barrels. I wouldn't take a barrel from a manufacturer with a bad reputation regardless of what method he used to make it.

 

[mete]

Sintered metal - the proper term is Powder Metal [PM] .Part of the process is to sinter -heat to high temperature to bond the powder particles together. PM parts can very considerably as far as density .The lowest density are used as filters .Remington specialized in high density which involved double pressing and sintering to give properties closely matching forged parts.
MIM is a 'second generation' PM . powder is mixed with a wax like polymer which is injection molded. The polymer is then melted out .Then the part is sintered to bond the particles.
In either process there are many variables ,starting with picking which parts are applicable and of course QC must be there !

 

[CraigC]

Missing the point.

I am not missing the point. You cannot blanketly say that "MIM parts are used in aircraft so that eradicates all possibility that the process results in poor quality parts". That statement is useless without regard for the specific application. Used in aircraft for what? For seat brackets? High heat applications within the turbine engines? What's the replacement rate?

Again, I am not an aircraft connoisseur. I don't care how they are made as long as they work. If I regarded guns as merely "tools", then my attitude would be the same. I do not. I am a revolver connoisseur. This is not a casual hobby. I care about how my guns are made because they are my only passion. I'm sorry but a revolver with disposable innards, an atrocious internal lock and jacked-up price tag does not appeal to me. Drop the price, ditch the lock and I can live with the MIM parts. Just recently I had the choice between an older S&W 24-3 or a new "Classic" model. I even found the new version used for $629. Instead I bought the older gun at $850. I'll do that every time, no matter which version costs less. IMHO, the new S&W's just have too much that must be overlooked.

As I said before, I believe the name has as much to do with the stigma as the process. Call it something other than "injection molding" and we probably wouldn't even be having this discussion.

 

[SIGSHR]

One complaint I have seen about MIM is that because they use a tiny amount-3% (?) of plastic-needed for the process-such parts cannot be blued or plated.

 

[OldMarksman]

You cannot blanketly say that "MIM parts are used in aircraft so that eradicates all possibility that the process results in poor quality parts". That statement is useless without regard for the specific application. Used in aircraft for what? For seat brackets? High heat applications within the turbine engines? What's the replacement rate?

They are used in some critical engine parts; the time between overhauls is typically less than 5,000 hours. I have no idea whether those parts are replaced then or simply inspected.

They are also used in orthopedic implants--plates, spinal parts, and so forth. Those are things you do not want to have to replace--ever.

Some years ago, when MIM fabrication was new, there were parts rejection problems. Things have come a long way in terms of process control and inspection and testing practices.

Decades ago, much less advanced powder metallurgy techniques were sometimes used in mission-critical applications in space. That choice was made in order to allow the use of special metals that could not be processed in any other way; the benefit was lighter weight and improved stiffness, and not cost.

I tend to think that in general, it's process control that counts--kinda like why you would not want to shoot a Model 1903 rifle with a single heat treated carbon steel receiver.

However, it seems to me (but I do not know this as a fact) that the MIM process would result in parts that would not be amenable to smooth polishing or fine surface finishing. That might be OK for a gun that is used as a tool, but it might not be desirable in something that's also supposed to look good.

 

[Shane Tuttle]

They are used in some critical engine parts; the time between overhauls is typically less than 5,000 hours. I have no idea whether those parts are replaced then or simply inspected.

Which parts?

I think it's difficult to compare aircraft parts made from MIM and firearms parts. In the aviation industry, there's stricter standards on inspection processes of parts before being deemed serviceable. I highly doubt any firearms manufacturer or the parts manufacturer for said firearm will inspect each and every MIM part like we do in the aviation industry.

 

[jaydubya]

Monitor -- Time?

Jack

 

[JohnKSa]

You cannot blanketly say that "MIM parts are used in aircraft so that eradicates all possibility that the process results in poor quality parts".

Nobody is saying that. The claim isn't that there is no possibility that the MIM process results in poor quality parts--ANY process, poorly implemented can result in poor quality parts.

The REVERSE claim has been made--namely that MIM parts are ALWAYS poor quality parts and can't be made to be durable and strong. The fact that they are used in aircraft applications proves that they CAN be made durable and strong.

The point is that if MIM parts fail prematurely or are defective it's NOT because they are MIM parts it's because they are poor quality MIM parts. Basically the same reason that forged or cast parts fail prematurely or are defective--it's not the process, it's whether or not the process is implemented properly.

I'm sorry but a revolver with disposable innards...

Nobody wants that, but you're still equating MIM parts with disposable parts. That is not automatically true. MIM parts CAN be made durable and strong if they're made right. If a revolver has "disposable innards" then it's SOLELY because the manufacturer doesn't care about the quality of the product. A revolver can have parts made from castings, forgings or MIM and still be a quality product if things are done right and the manufacturer cares about quality.

In the aviation industry, there's stricter standards on inspection processes of parts before being deemed serviceable. I highly doubt any firearms manufacturer or the parts manufacturer for said firearm will inspect each and every MIM part like we do in the aviation industry.

We can speculate about what level of inspection is required to insure quality of an MIM part and about how much inspection firearms manufacturers do on their parts or require of their parts suppliers but at least we agree that it's the care taken to insure quality that makes the difference in the quality of the resulting parts.

 

[CraigC]

Nobody wants that, but you're still equating MIM parts with disposable parts.

They ARE disposable. They cannot be reforged, hardened or welded upon. They can only be replaced.

Something that I have to reiterate is that we've always paid more for S&W's (than Ruger for example) because we believed we were getting a superior product. If there is little to no hand-fitting, if the guns are polished in a tumbler, what exactly are we paying extra for???

 

[JohnKSa]

They ARE disposable. They cannot be reforged, hardened or welded upon. They can only be replaced.

Ah, I see how you're using the term. I suppose that if the ability to reforge/harden/weld the internal parts of your revolver is important then the use of even high-quality MIM parts reduces the value of the gun to you.

Most people wouldn't want to (or wouldn't have the means to) reforge or reweld a broken part, they'd replace it with a new part even if it were possible to repair it. I guess to them any part that broke would be "disposable" (in the sense that you're using the word) regardless of how it was made and the fact that it couldn't be "recycled/repaired" would be moot.

For what it's worth, that's not really how the word 'disposable' is commonly used. 'Disposable' means something that's designed for single (or very limited) use and that is meant to be thrown away after that use regardless of condition.

http://www.merriam-webster.com/dictionary/disposable

1 : subject to or available for disposal; specifically : remaining to an individual after deduction of taxes and necessary living expenses <disposable income>
2 : designed to be used once and then thrown away <disposable diapers>​

I'm not sure that there's a good word that fits the meaning you've imposed on 'disposable' but something like "non-repairable part" is probably close.

...what exactly are we paying extra for?

I have no answer for you. The fact that I can't answer the question is a big part of why I don't own any S&W revolvers.

 

[CraigC]

Most people wouldn't want to (or wouldn't have the means to) reforge...

What about doing a trigger job? You cannot recut the sear engagement surfaces and then reharden the part, the way you can with any other.

...or reweld a broken part...

This is also exactly what we have to do with older guns. Since the supply of forged parts is drying up, due to the influx of MIM parts, old parts have to be repaired if damaged. Not even something out of reach of the average amateur gunsmith.

2 : designed to be used once and then thrown away <disposable diapers>

I think I know what disposable means. There's no time constraint on "used once". You don't throw away a disposable cigarette lighter after using it one time, do you?
From Webster's:
"1. designed for or capable of being thrown away after being used or used up: disposable plastic spoons; a disposable cigarette lighter."

 

[Shane Tuttle]

We can speculate about what level of inspection is required to insure quality of an MIM part and about how much inspection firearms manufacturers do on their parts or require of their parts suppliers but at least we agree that it's the care taken to insure quality that makes the difference in the quality of the resulting parts.

I can agree with that, John.

 

[FrankenMauser]

Used in aircraft for what? For seat brackets? High heat applications within the turbine engines? What's the replacement rate?

In our birds, there were brackets, gears, gearbox casings, valve pistons, valve bodies, and tons of engine parts made with MIM processes. (The original designs were cast/milled, but not the newer parts.)

Our engines had an 'minor' overhaul interval of 6,000 hours (2-3 years). It was basically a detailed inspection, and replacement of long-life filters.

The 'major' overhaul was done at 15,000-20,000 hours. (It depended upon the date of serialization - some engines were 40 years old; and some 2 years old. Regardless of how new all the parts were, the date of creation for that serial number was what determined its overhaul interval).
A 'major' overhaul saw many new parts, and replacement of 50-60 compressor blades and 30-40 turbine (power, or "combustion") blades. With a rotation speed of 22,500-48,000 rpm; we never had a failure. They had to be replaced due to erosion, from particles in the air.

The interesting part, was the life and cost of MIM versus cast compressor blades. (It was a toss up for other parts. They usually failed, due to outside influences.)
Cast blades used to require almost 100% replacement, at each overhaul. With over 800 blades in our engines; at $1000+, per blade; that's one hell of a price tag.
The MIM blades lasted through several overhauls, with only the 'high wear' sections being replaced often. The ability to make the MIM blades lighter, at the desired hardness, and precisely the desired shape, allowed the price tag to drop to around $150 each (each blade is unique, and has it's own exact price).

The added consistency of the injection process also made life easier for us, in the vibration department. Cast blades liked to bend, chip, and change shape when heated. The MIM blades resisted all of this. The tiniest imperfection, at 40k rpm, can cause major vibrations in a turbine engine. Having the MIM parts keep those vibes down; gave us longer life with other parts, and let us zone in on other vibrations in the helicopter (more so than we could in the past).


Again - They only worked, because they were made with the correct process, and a high amount of quality control. Going cheap with the process, or ignoring quality control gives horrible parts.
I trust good MIM parts; if they're appropriate for the application. (Triggers, sears, hammers, etc are fine)
If they're bad parts, or not a good choice for the application; MIM is bad news. (Barrels, cylinders, slides, firing pins, and frames... I'm not likely to trust.)

 

[JohnKSa]

Craig,

I didn't say that NO one wanted to reforge/reweld parts or that there was never a situation where it made sense. I said that MOST people wouldn't want to or have the means to and I don't really think it's possible to dispute that.

Whether it's within or outside the reach of the "average amateur gunsmith" is also irrelevant to my statement. I'm sure that the things you describe are all "within my reach" but even though I tinker more than most I have no plans to get into recutting/rehardening/rewelding internal gun parts. As long as a part provides a reasonably long, problem free service life I'm happy with it. I think you would agree that the vast majority of gun owners feel the same way which means that what I said (most wouldn't want to reforge/reweld parts) is correct.

The word "disposable" carries with it the connotation of limited/single/short use. High quality MIM parts are designed to provide a lifetime (maybe even a few lifetimes) of service. That's not really within the typical definition of "disposable".

If you take the time constraint out of the meaning of "disposable" then anything that can't be remanufactured/reworked/rebuilt is disposable--even if it's designed to provide many decades of service. That's not what people mean when they say "disposable". Disposable definitely implies short use--a disposable lighter isn't designed to be used/useful as long as a refillable lighter. Disposable diapers aren't designed to be used/useful as long as non-disposable diapers. A disposable anything is not designed to last as long as a non-disposable item made for the same purpose.

So when you say that MIM parts are "disposable" you're implying that they won't last as long as forged/cast parts. In reality, quality MIM parts can provide just as long a service life as forged/cast parts. The fact that you can rework/reweld/etc. the forged parts (and some of the cast parts) doesn't make the MIM parts "disposable" it just means that they can't be reworked/rewelded/etc.

 

[skeeter]

The big issue with MIM parts more than anything is their application.
MIM parts are not used to give the customer a higher quality product. They are used to make more profit for the manufacturer and maybe pass on some savings to the customer?
Colt learned an important lesson about application when at a time they used MIM extractors in their 1911's. The failure rate and warranty work showed Colt they would not be saving any money with MIM parts used in this application.
Think of it like concrete in a way. We all know how strong it can be but would you want to use a concrete diving board for any length of time?
As far as MIM use in aircraft, well aircraft parts are usually have a built in 3 times the strength needed requirement. Engine parts are checked at certain usage hours unlike firearms. MIM parts being light and brittle are perfect for turbine blades but you do not want to subject brittle parts to high impact loads like Kimbers barrel bushings or slide stops that I personally saw 2 failures at my local range.

I would like to ask all of the MIM supporters if their families life was on the line would you choose a 1911 loaded with MIM parts or a 1911 made of billet steel parts? Lets be honest now.

 

[CraigC]

The fact that most things considered disposable have short life spans is irrelevant. Your typical el cheapo car is also designed for many years of service (its lifetime) but many consider them "disposable" because they cannot be rebuilt. Much like the old saying that old Harley's get rebuilt, old Hondas get scrapped. Same concept.

The fact that gun owners cannot weld and/or reharden the parts is equally irrelevant. You do realize that we have more talented gunsmiths now than ever, right? You also realize that adjusting sear engagement and rehardening the affected surfaces is rather common practice in trigger/action jobs, right? This 'may' not seem like a big deal at present but what if S&W goes out of business tomorrow? In 20yrs if you break the sear engagement on your trusty late model 686 you are out of luck. If yours is an older gun the hammer can be welded up, recut and rehardened. I'm sorry but try as I might, I just can't look at the two guns the same way. It's a sign of the times, everything is getting cheaper AND more expensive. Like I said before, not a big deal on a 1911 when any internal part that may break can be replaced with an aftermarket part of your choice for fifty bucks or less. Not so with a late model S&W revolver.

So when you say that MIM parts are "disposable" you're implying that they won't last as long as forged/cast parts.

I'm not implying anything. I'm stating blatantly that MIM parts are disposable, meaning they cannot be rebuilt or reused. At this point we really don't know how they hold up long term, do we?

 

[kalstrand]

If S&W goes out of business tomorrow someone will start making replacement parts at some point. Just like you can pretty much build a 69 camaro out of new reproduction parts.