What is "MIM"

[retired2006]

Probably a dumb question, but what does "MIM" stand for, and how are MIM parts made ?

 

[retired2006]

Probably a dumb question, but what does "MIM" stand for, and how are MIM parts made ?

 

[ANGST]

Metal Injection Molding

Metal injection molding or (MIM) is a manufacturing process which combines the versatility of plastic injection molding with the strength and integrity of machined, pressed or otherwise manufactured small, complex, metal parts. Competing processes include pressed powder, investment casting, turning and machining.

The process involves combining fine metal powders with a plastic binders which allow the metal to be injected into a mold using standard plastic injection molding machines. The binders are then removed by solvent and thermal processes and the resultant metal part is sintered at temperatures great enough to bind the particles but not melt the metal. The products of metal injection molding are up to 98% as dense as wrought iron and used in a broad range of applications (including medical, dental, firearms, aerospace, and automotive just to name a few.)

The window of economic advantage in metal injection molded parts lies in the complexity and small size of the part. Tolerances as small as +/-.003" per linear inch can be usually be held without secondary processes. The difficulty of fabrication through other means may make it cost inefficient or even impossible to manufacture otherwise. Increasing complexity for traditional manufacturing methods typically does not increase cost in a metal injection molding operation due to the wide range of features possible through injection molding (threads (both internal and external), miniaturization, branding).

 

[Ol' M&P]

Some folk find MIM parts not traditional.
They are right.
However, MIM parts are tough and fit very well. They require very little fitting when doing an action job.
I bobbed a 317 hammer with a Dremmel cut off wheel and it was too hard to shape with a file!

 

[retired2006]

Thanks for the excellent answer. I have asked several people exactly what the MIM was, and had not gotten an answer, except that if it was a Smith revolver, they didn't want one with MIM parts.

 

[Wyatt Earp]

Originally posted by retired2006:
Thanks for the excellent answer. I have asked several people exactly what the MIM was, and had not gotten an answer, except that if it was a Smith revolver, they didn't want one with MIM parts.

I am a manufacturing engineer with 15 years experience in machining, fixturing, metal working, and process control.

The overwhelming majority of people who complain about modern materials in firearms do not have the first earthly clue about what they are saying.

Ignoring them is the best course of action.

PS, both Ferrari and Porsche piston connecting rods are made by the metal injection molding process. Anyone who questions the commitment to quality of those two automakers is a fool of the highest order.

 

[pangris]

Originally posted by Wyatt Earp:

PS, both Ferrari and Porsche piston connecting rods are made by the metal injection molding process. Anyone who questions the commitment to *profit* of those two automakers is a fool of the highest order.

Fixed it for you

What do they use in the race cars they track for their factory teams?

FWIW, I trust my life to MIM every day, and the rest of you probably do as well - I was recently informed the gears in my BMW's transmission are MIM. IIRC I heard GM was using some advanced casting process for their gears.

I've got MIM in my guns and I don't lose sleep over that - that said - given the choice, give me forged in a race car or a carry gun...

 

[Mickey D]

What is "MIM"

It's mum for a British hairlip.

 

[SJshooter]

Originally posted by pangris:

Originally posted by Wyatt Earp:

PS, both Ferrari and Porsche piston connecting rods are made by the metal injection molding process. Anyone who questions the commitment to *profit* of those two automakers is a fool of the highest order.

Fixed it for you

What do they use in the race cars they track for their factory teams?

AFAIK, they use MIM in those, as well. And if Ferrari cared about profit more than quality they could easily crank out more cars instead of limiting production and make more money any time they wanted to.

 

[G-Mac]

Connecting rods and transmission gears made by MIM, huh?

I find that interesting.

Funny, we look down on MIM parts on Smiths, but we have no problem having a plastic Glock in the safe right next to our old all-steel Smiths with forged, case-colored parts.

I think it's about breaking tradition...revolvers are "old-school". MIM is not.

Personally, to me, a gun has more "soul" if it was made by machine tools and skilled craftsmen rather than having come out of a mold.

I respect custom gun makers, and I could name several, that say they will use MIM parts "under no circumstances".

There's a reason for that, I think.

 

[Wyatt Earp]

Originally posted by G-Mac:
Personally, to me, a gun has more "soul" if it was made by machine tools and skilled craftsmen rather than having come out of a mold.

Then get ready to pay upwards of $2000 for a handgun and close to $5000 for a rifle. If you want to see what a gun made your way costs, price a shotgun made by Connecticut Shotgun Manufacturing or Fabbri.

BTW, it takes machine tools and skilled craftsmen to make the molds and dies that are used to make castings and MIM parts.

Originally posted by G-Mac:
I respect custom gun makers, and I could name several, that say they will use MIM parts "under no circumstances".

There's a reason for that, I think.

I bet the reason has nothing to do with reality and all to do with catering to a market that demands certain things in their guns regardless of how much technical validity there may be to those requests.

 

[pangris]

Originally posted by SJshooter:
AFAIK, they use MIM in those, as well. And if Ferrari cared about profit more than quality they could easily crank out more cars instead of limiting production and make more money any time they wanted to.

Negative on both.

When high end manufacturers try to mas produce cheaper stuff, it diminishes the cache of the brand - hence, they are what they are - a boutique that can charge an insane amount. It isn't that they care MORE about profit than quality, it is that if it is les expensive and the difference in the failure rate is virtually non existant... so be it.

As far as MIM guts in factory racers - 99% of sponsored teams use forged EVERYTHING. When you get into a ONE LITER engine that makes 1100 HP - you need every bit of strength you can get.

 

[G-Mac]

This is copied and pasted from Ed Brown's FAQ section of his web-site...

Q: Do Ed Brown handguns have any MIM (metal injection molded) parts?

A: No, we use no MIM parts in Ed Brown firearms. While the current thinking is that MIM parts are "good enough" for firearm applications, this thinking doesn't fit with our philosophy at all. All Ed Brown parts are made from either forgings, bar stock steel, or quality investment castings.

Wyatt Earp,

I, too, worked in manufacturing for a long time. My knowledge of, and experience in working with productions engineers, has taught me that they are responsible for producing as many widgets as humanly possible...in the shortest amount of time...and to an ACCEPTABLE quality standard.

Now...I'll admit that MIM has come a long way and, done correctly, will produce very consistent "widgets". But...let's not try to fool anybody here...the move to MIM is also largely based on cost savings. Yes...it might take a tool and die maker to produce the mold, But once it's made, it still eliminates a lot of the skilled workers that built say...Registered Magnums or Pre-1964 Winchesters. It doesn't take a rocket scientist to push the buttons on an injection-molding machine.

I fully understand that's the reason a gun like an Ed Brown costs more...and that's why I'll buy a 1950's K-22 before I'll buy a new piece of crap with MIM parts, a stupid lock, and a finish that looks like it came out of Star Wars.

 

[bk43]

I think it's a given that custom smiths like Ed Brown are opposed to MIM parts. Their livelyhood depends on taking parts that don't fit well(non-MIM) and hand fitting them. A MIM part only has to be made exactly right once and that is when the mold is made. After that they're all exactly right.

Bob

 

[G-Mac]

Originally posted by bk43:
I think it's a given that custom smiths like Ed Brown are opposed to MIM parts. Their livelyhood depends on taking parts that don't fit well(non-MIM) and hand fitting them. A MIM part only has to be made exactly right once and that is when the mold is made. After that they're all exactly right.

Bob

I agree with you on that. But, I still prefer a forged, properly hand-fitted part to an MIM part.

 

[Wyatt Earp]

Originally posted by G-Mac:
But...let's not try to fool anybody here...the move to MIM is also largely based on cost savings. Yes...it might take a tool and die maker to produce the mold, But once it's made, it still eliminates a lot of the skilled workers that built say...Registered Magnums or Pre-1964 Winchesters. It doesn't take a rocket scientist to push the buttons on an injection-molding machine.

I fully understand that's the reason a gun like an Ed Brown costs more...and that's why I'll buy a 1950's K-22 before I'll buy a new piece of crap with MIM parts, a stupid lock, and a finish that looks like it came out of Star Wars.

If gunmakers all thought like you there would be no gunmakers left in business because nobody could afford their new products.

And pretty soon the price of old guns would skyrocket out of sight because there are no new guns to buy. Simple supply and demand.

Thankfully some people have business sense.

 

[pangris]

Originally posted by Wyatt Earp:

Thankfully some people have business sense.

I can not believe an engineer just said those words.

 

[Wingwiper]

I am a manufacturing engineer with 15 years experience in machining, fixturing, metal working, and process control.

PS, both Ferrari and Porsche piston connecting rods are made by the metal injection molding process. Anyone who questions the commitment to quality of those two automakers is a fool of the highest order.

Well, at 12,000 miles on my new BMW I consulted with the car's computer (through the i-Drive) to see when it thought that the very first oil change was needed. The computer, as programmed by the <STRIKE>*cost*</STRIKE>, er quality-minded folks at BMW (who are paying for all maintenance for the first four years) told me not to worry - I could go another 8,000 miles before one was needed.

Call me a "Fool Of The Highest Order" all you want, but I changed the oil anyway.

 

[ShakyJake]

Hi, Wyatt Earp
Could you explain the difference between MIM and injection molding and where the Ruger process fits in the picture. Love them or lump them they are considered some of the strongest revolvers going. I also have had some 'smiths tell me that the reason they do not like MIM is because it is much harder and therefore not as easy to work on.
Thanks for your help
TaKe CaRe
Ted

 

[Wyatt Earp]

Originally posted by pangris:

Originally posted by Wyatt Earp:

Thankfully some people have business sense.

I can not believe an engineer just said those words.

I've been successfully managing capital projects in manufacturing companies for some time now. I would be unemployed if I didn't understand how to help a business make money.

My current customer is Honda of America.