MIM Parts
- Thread starter SHAMUSPI
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PERSONALLY, I THINK THAT MIM PARTS, ESPECIALLY FROM S&W, HAVE PROVEN THAT THEY ARE TROUBLE FREE. TO ME HOWEVER, IT IS THE COSMETICS. IN A BLUE, PARKERIZED, OR TWO TONE GUN, I WOULD NOT MIND THEM. BUT BLACK MIM OVER STAINLESS.... YUUUUUK! JUST MY OPINION THOUGH 
Here is an interesting item on MIM parts from a S&W manager, which I copied from this forum some time ago (it is at least eight years old, maybe older, but still pertains):
FAQ's: http://smith-wessonforum.com/s-w-smithing/94072-faqs.html#post1029055 for the 'original' letter.
I have read with much interest the many comments in this [Smith and Wesson] forum pertaining to MIM, MIM Parts and the use of same in a S&W product. So far I have come away with several impressions and they are, "people in general don't like/trust MIM parts", and, "no one has said why." I will take a stab at this issue and see where it goes.
As background to our decision to use MIM in some areas of our Mfg Process we took a long hard look at our "Life Time Service Policy". It was clear to us that any change in any of our products such as the use of MIM components had to show equivalent or better performance and durability to those components that were being replaced or the "Lifetime Service" would haunt us forever. The second consideration was to determine if the change was too radical a departure from S&W mainstream design.
For the performance and durability issues we decided that if MIM could be used for the fabrication of revolver hammers and triggers successfully this would truly be an "Acid Test". There is nothing more important to a revolver's feel than the all-important Single Action that is established between the hammer and the trigger. Mechanically few places in a revolver work harder than at the point where the hammer and trigger bear against each other. If these surfaces wear or lose their edge the "feel" is lost. Initial testing was on these two critical parts.
Over time we arrived at a point where our best shooters could not tell the difference between a revolver with the old-style hammer and trigger and the new MIM components. Special attention was given to their endurance when used in our very light magnum J-frames such as the early prototype 340 & 360 Sc's. None of our revolvers work their components harder than these small magnum revolvers. Throughout this testing MIM held strong and finally we determined that this change judged on the basis of durability and feel was a good one.
The second area of concern to S&W was our customer's reaction to this departure from the traditional. Many heated, intense discussions resulted but in the end the decision was made to move ahead with MIM. The issue of cost was only one of the considerations in making this decision. Equally as important was the issue of part-to-part uniformity and the result of this of course is revolver-to-revolver consistency. We found that revolvers that used MIM hammers and triggers required almost no fitter intervention in those areas during final assembly and final inspection and trigger-pull monitor rejection rates dropped markedly on finished guns. From an internal process point of view it appeared a "Winner".
Let's shift gears for a moment and talk about the MIM process. It is unclear to me as to the reason for many of the negative feelings on the forum concerning MIM. Typically when people complain and aren't specific in the reason why, the problem is often created by a departure from the "Traditional". Perhaps that is indeed what is bothering some people when they view MIM.
The term MIM stands for Metal Injection Molding. It holds some similarities to Plastic Injection Molding and many differences as well. To start we would take a finally divided metal powder. This could be stainless or carbon steel. Today even titanium is being used in some MIM fabrications. We would mix the metal powder and a thermoplastic binder (generally a wax) forming slurry of sorts when heated and inject this mix into a precision mold and finally form what is known as a "green part". This part is roughly 30% larger than the finished part it will become at the end of the process. Interestingly enough the green part at this stage can be snapped in two with simple finger pressure. The green parts are then placed in a sintering furnace filled with dry hydrogen gas and the temperature is brought almost to the melting point of the metal being used. Over time the wax in the green part is evaporated, the metal fuses and the part shrinks 30% to it's final correct dimensions. At this stage of the process the MIM part has developed 98 to 99%of the density of the older wrought materials and a metallurgy that is almost identical. Dimensionally it is finished and no machining is required. However the job is not yet done and the MIM parts are brought to our heat treat facility for hardening and in the case of hammers and triggers, case hardening. Depending on the particular metal alloy that was used at the start of the process we apply a heat treat process that is the same as would be used if the material were the older wrought style. Final hardness, case thickness and core hardness are for the most part identical to parts manufactured the older way.
Lets look for a moment at how we achieve dimensional precision when comparing these 2 processes. The old parts were each machined from either bar stock or a forging. Each cut and every resulting dimension was subject to machine variations, cutter wear, operator variations etc. If every operation was done exactly right each and every time and the cutter didn't let you down you would have produced a good part but sometimes this didn't happen, resulting in a rejected gun and rework or in the worst case an unhappy customer. With MIM parts you must still machine to very high tolerances and your cutters have to be perfect and your machinist has to be highly qualified but all of this only has to come together one time. That time is when the injection mold is made. Typically a mold for this process costs S&W between $30,000.00 and $50,000.00; once it is perfect every part it makes mirrors this perfection and you have, in my view, a wonderful manufacturing process.
Hopefully this description will help us all better understand the MIM process. Please forgive the spelling errors and misplaced punctuation. I have no spell checker on this and the phone continues to ring!
Have a Great Weekend,
Herb [Belin, Project Manager, Smith & Wesson]
Additional Point:
Currently S&W is paying about $1.20/Lb for stainless steel bar stock. Raw MIM stainless steel inject able material costs $10.00/Lb.
FAQ's: http://smith-wessonforum.com/s-w-smithing/94072-faqs.html#post1029055 for the 'original' letter.
I have read with much interest the many comments in this [Smith and Wesson] forum pertaining to MIM, MIM Parts and the use of same in a S&W product. So far I have come away with several impressions and they are, "people in general don't like/trust MIM parts", and, "no one has said why." I will take a stab at this issue and see where it goes.
As background to our decision to use MIM in some areas of our Mfg Process we took a long hard look at our "Life Time Service Policy". It was clear to us that any change in any of our products such as the use of MIM components had to show equivalent or better performance and durability to those components that were being replaced or the "Lifetime Service" would haunt us forever. The second consideration was to determine if the change was too radical a departure from S&W mainstream design.
For the performance and durability issues we decided that if MIM could be used for the fabrication of revolver hammers and triggers successfully this would truly be an "Acid Test". There is nothing more important to a revolver's feel than the all-important Single Action that is established between the hammer and the trigger. Mechanically few places in a revolver work harder than at the point where the hammer and trigger bear against each other. If these surfaces wear or lose their edge the "feel" is lost. Initial testing was on these two critical parts.
Over time we arrived at a point where our best shooters could not tell the difference between a revolver with the old-style hammer and trigger and the new MIM components. Special attention was given to their endurance when used in our very light magnum J-frames such as the early prototype 340 & 360 Sc's. None of our revolvers work their components harder than these small magnum revolvers. Throughout this testing MIM held strong and finally we determined that this change judged on the basis of durability and feel was a good one.
The second area of concern to S&W was our customer's reaction to this departure from the traditional. Many heated, intense discussions resulted but in the end the decision was made to move ahead with MIM. The issue of cost was only one of the considerations in making this decision. Equally as important was the issue of part-to-part uniformity and the result of this of course is revolver-to-revolver consistency. We found that revolvers that used MIM hammers and triggers required almost no fitter intervention in those areas during final assembly and final inspection and trigger-pull monitor rejection rates dropped markedly on finished guns. From an internal process point of view it appeared a "Winner".
Let's shift gears for a moment and talk about the MIM process. It is unclear to me as to the reason for many of the negative feelings on the forum concerning MIM. Typically when people complain and aren't specific in the reason why, the problem is often created by a departure from the "Traditional". Perhaps that is indeed what is bothering some people when they view MIM.
The term MIM stands for Metal Injection Molding. It holds some similarities to Plastic Injection Molding and many differences as well. To start we would take a finally divided metal powder. This could be stainless or carbon steel. Today even titanium is being used in some MIM fabrications. We would mix the metal powder and a thermoplastic binder (generally a wax) forming slurry of sorts when heated and inject this mix into a precision mold and finally form what is known as a "green part". This part is roughly 30% larger than the finished part it will become at the end of the process. Interestingly enough the green part at this stage can be snapped in two with simple finger pressure. The green parts are then placed in a sintering furnace filled with dry hydrogen gas and the temperature is brought almost to the melting point of the metal being used. Over time the wax in the green part is evaporated, the metal fuses and the part shrinks 30% to it's final correct dimensions. At this stage of the process the MIM part has developed 98 to 99%of the density of the older wrought materials and a metallurgy that is almost identical. Dimensionally it is finished and no machining is required. However the job is not yet done and the MIM parts are brought to our heat treat facility for hardening and in the case of hammers and triggers, case hardening. Depending on the particular metal alloy that was used at the start of the process we apply a heat treat process that is the same as would be used if the material were the older wrought style. Final hardness, case thickness and core hardness are for the most part identical to parts manufactured the older way.
Lets look for a moment at how we achieve dimensional precision when comparing these 2 processes. The old parts were each machined from either bar stock or a forging. Each cut and every resulting dimension was subject to machine variations, cutter wear, operator variations etc. If every operation was done exactly right each and every time and the cutter didn't let you down you would have produced a good part but sometimes this didn't happen, resulting in a rejected gun and rework or in the worst case an unhappy customer. With MIM parts you must still machine to very high tolerances and your cutters have to be perfect and your machinist has to be highly qualified but all of this only has to come together one time. That time is when the injection mold is made. Typically a mold for this process costs S&W between $30,000.00 and $50,000.00; once it is perfect every part it makes mirrors this perfection and you have, in my view, a wonderful manufacturing process.
Hopefully this description will help us all better understand the MIM process. Please forgive the spelling errors and misplaced punctuation. I have no spell checker on this and the phone continues to ring!
Have a Great Weekend,
Herb [Belin, Project Manager, Smith & Wesson]
Additional Point:
Currently S&W is paying about $1.20/Lb for stainless steel bar stock. Raw MIM stainless steel inject able material costs $10.00/Lb.
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BruceM
Member
Thanks S&W Rover.
Every once in awhile facts need to rule over emotion and hearsay. MIM has come a long, long way since folks like Dornaus & Dixon pioneered it in firearms in the early 1980's and the big "K" raped it's reputation in the early 2000's. The realization that MIM major components are used in applications in the aviation and automotive industries cast a different light on this "life and death" firearms conversation or at least it should.
Anyway, Smith & Wesson uses very high quality MIM components in a few appropriate applications. Applications that MIM is NOT appropriate for are things which flex such as springs and internal 1911 extractors.
It always makes me chuckle when some "expert" expounds on this and other forums that he doesn't want any of those "cheap pot metal MIM parts" in his self defense guns.
Bruce
Every once in awhile facts need to rule over emotion and hearsay. MIM has come a long, long way since folks like Dornaus & Dixon pioneered it in firearms in the early 1980's and the big "K" raped it's reputation in the early 2000's. The realization that MIM major components are used in applications in the aviation and automotive industries cast a different light on this "life and death" firearms conversation or at least it should.
Anyway, Smith & Wesson uses very high quality MIM components in a few appropriate applications. Applications that MIM is NOT appropriate for are things which flex such as springs and internal 1911 extractors.
It always makes me chuckle when some "expert" expounds on this and other forums that he doesn't want any of those "cheap pot metal MIM parts" in his self defense guns.
Bruce
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It sounds like you are replacing the parts for 'mental' reasons.
I don't think machined parts are necessarily better than MIM.
To assure reliability both would need to be made by quality processes and xrayed for defects.
I doubt you will get parts in either category made with such quality control processes to get the reliability you need.
If you want such reliability buy a glock or M&P, the designs are the current state of the art in high reliability police/professional use.
ANY gun made for the commercial market even with bar stock forged parts won't have modern engineering and quality control behind it.
You won't have a engineer designing it with a MTBF or mean time before failure analysis going on.
Bluntly commercial guns have commercial quality and no one is doing engineering analysis on their products other than to ensure any warranty period is satisfied.
I don't think machined parts are necessarily better than MIM.
To assure reliability both would need to be made by quality processes and xrayed for defects.
I doubt you will get parts in either category made with such quality control processes to get the reliability you need.
If you want such reliability buy a glock or M&P, the designs are the current state of the art in high reliability police/professional use.
ANY gun made for the commercial market even with bar stock forged parts won't have modern engineering and quality control behind it.
You won't have a engineer designing it with a MTBF or mean time before failure analysis going on.
Bluntly commercial guns have commercial quality and no one is doing engineering analysis on their products other than to ensure any warranty period is satisfied.
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TO EACH HIS OWN I GUESS MY FRIEND, BUT PERSONALY I WOULD PICK ANY MIM OVER ANY TUPPERWEAR ANYTIME. AND I AM NO MIM FAN.
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I have and enjoy both smith and Wesson and glocks. I even have a billboard stainless 1911 and a model 64with the dreaded mim parts. They all work as advertised and have never given me any problems. I completely understand those who love the traditional steel and wood guns- so do I. I have a couple of m1 garands that are kind of my showpieces. But you know the old saying- your beautiful 1911 is what you show your friends- your glock is what you show your enemies! Haha!
OP
SHAMUSPI
Member
WOW! When I posted my question I was hoping for a couple of replies, but not to create a firestorm. I will admit, you guys having me rethinking the idea of replacing parts that may be just as good as their replacements. Being that I am as old as dirt, I probably have been influenced by MIM failures when they first came out. In any case, THANKS TO ALL!
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It's ok. Firestorms and healthy debate are fun! I've accidentally started a few myself! How boring would life be if we all liked the same things in exactly the same way???? Yeah I don't want that either.
WisconsinKen
Member
I would not argue that the after market machined parts are not better than the MIM parts in my 1911SC. Take for instance the ambi safety. Perfectly functional so far in my SC. However, it is not nearly as nice as the Wilson ambi I put on my Billboard. So, it really boils down to personal taste and the acceptable price point.
FWIW ... (what you paid for it 
) ... I've been using MIM 3rd gen parts since I was introduced in them toward the end of the 90's, and typically found them to exhibit better, tighter tolerances than the same forged or cast steel parts.
Also, in my '05 vintage SW1911SC 5", the only part that "failed" after several years was a plunger tube (staking let go), which isn't a MIM part.
I'm a long time 1911 owner/shooter (and went through the Colt Model O Pistol armorer class), so I'm somewhat fussy about the quality of the parts that go in my 1911's.
Now, just like when we're talking machined forged & cast parts, where the quality of forged and cast may run the gamut of quality being anywhere from not-so-good to great, the same might be said of MIM. Also, in addition to the quality of the MIM material, there's the quality of the MIM molds to consider.
That's why we were told (in a late 90's armorer class) that S&W wisely decided to select and own the MIM molds used to make their parts, even when they're made by an out-sourced "MIM house" vendor, so they can have control over the quality of the molds, themselves.
I won't name the gun company involved, but some years ago I remember hearing how one gun company once took bids for MIM parts for their branded pistols, and when they got bids for the work, decided to use a vendor that offered a less expensive bid.
) ... I've been using MIM 3rd gen parts since I was introduced in them toward the end of the 90's, and typically found them to exhibit better, tighter tolerances than the same forged or cast steel parts.Also, in my '05 vintage SW1911SC 5", the only part that "failed" after several years was a plunger tube (staking let go), which isn't a MIM part.
I'm a long time 1911 owner/shooter (and went through the Colt Model O Pistol armorer class), so I'm somewhat fussy about the quality of the parts that go in my 1911's.
Now, just like when we're talking machined forged & cast parts, where the quality of forged and cast may run the gamut of quality being anywhere from not-so-good to great, the same might be said of MIM. Also, in addition to the quality of the MIM material, there's the quality of the MIM molds to consider.
That's why we were told (in a late 90's armorer class) that S&W wisely decided to select and own the MIM molds used to make their parts, even when they're made by an out-sourced "MIM house" vendor, so they can have control over the quality of the molds, themselves.
I won't name the gun company involved, but some years ago I remember hearing how one gun company once took bids for MIM parts for their branded pistols, and when they got bids for the work, decided to use a vendor that offered a less expensive bid.
I think MIM started out with a bad reputation, for sure. I remember when the Sig Forum was scandalized because someone found pictures of some Sig-Sauer parts in an advertisement on a web page from an Indian metal company. I don't know if that Indian company really proved to be the source of those Sig parts, but they actually have a great reputation as a world-class producer of all sorts of MIM items.
But I think S&W (and Sig) have the MIM process down pretty good now. I have never had a part from a S&W (or a Sig!) gun break, through many thousands of rounds. On top of that, I would venture that for most parts for most guns, there really is only one source, and it often involves MIM.
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Could be the source for the many years of Sig substandard product.
I'm all for customizing and having options, but be aware that any of the parts you replace are just as likely to need fitting as they are to be drop-in. You can't just replace the hammer, sear, slide stop and thumb safety and expect the gun to function exactly like it did before. Make sure to keep the factory parts if replace anything because in the long run those parts are probably the best option.
If it makes you feel any better some Colt's come with a plastic mainspring housing.
If it makes you feel any better some Colt's come with a plastic mainspring housing.
HMMMM... I DO NOT KNOW ABOUT SPRINGFIELD FRIEND, BUT S&W SEEMS TO HAVE FORGOTTEN ABOUT WARRANTIES FOR THE 3RD GEMS ATLEAST. SO, AS MUCH AS I WOULD LIKE TO BELIEVE THAT MIM IS A BETTER OR EQUAL SOLUTION, I AM MORE CONVINCED THAT IT IS A MORE COST EFFECTIVE SOLUTION. AGAIN, COMPANIES ARE THERE TO MAKE A DOLLAR, AND I WILL NOT BE THE ONE TO JUDGE THEM. ITS A MARKET DRIVEN WORLD, AND WHAT THE MAJORITY OF THE MARKET WANTS, WE ALL END UP GETTING.
"THIS KEY SAY THE PADRE DROVE A MERCEDES. OR AT LEAST THATS WHAT THEY ARE PASSING OFF AS A MERCEDES THESE DAYS. MODERN CARS, THEY ALL LOOK LIKE ELECTRIC SHAVERS" (MARV, SIN CITY)
MIM is a cost cutting measure that profits the manufacturer. Nothing more. And when it breaks it looks exactly like cheap pot metal.
When I see Wilson Combat or Les Baer putting it in their guns then perhaps I will reconsider. But I don't consider or value, the opinions of fanboys.
I recall that the absence of MIM parts was a selling point in S&W Performance Center ads. Back before the "Performance Center" was just another assembly line in the main factory. YMMV. Regards 18DAI
When I see Wilson Combat or Les Baer putting it in their guns then perhaps I will reconsider. But I don't consider or value, the opinions of fanboys.
I recall that the absence of MIM parts was a selling point in S&W Performance Center ads. Back before the "Performance Center" was just another assembly line in the main factory. YMMV. Regards 18DAI
Arik
Member
Someone has to remind my revolver that only MIM hammers are supposed to break!
So far my experience is MIM parts broken 0. None MIM broken 1
Sent from my XT1650 using Tapatalk
So far my experience is MIM parts broken 0. None MIM broken 1
Sent from my XT1650 using Tapatalk
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