When did they start using MIM?

[HammerBite]

I have a deep distrust of MIM parts. It seems to me that the easiest away to avoid MIM parts is simply to buy older guns. The question is "how old?" Can anyone tell me when gun manufacturers started using MIM parts?

Thanks.

 

[50 Freak]

???????

More details man...more details....

Start with what gun are we talking about?

 

[steveno]

here we go again

 

[HammerBite]

Nobody is going anywhere . . .

I asked a simple question -- when did MIM come upon the firearms scene?

 

[steveno]

Kimber has been using MIM parts in most of their guns from the beginning. Most of the gun manufacturers probably use them wether they want to admit it or not. you can get good or bad parts regardless of the method used to make them. generally the gun companies aren't the first to come up with new manufacturing methods. these methods are normally a carry over from the aircraft or auto industry. the chances of MIM parts being used in critical locations on an airplane or car are a lot higher than most people think. would you let that affect wether or not you fly or ride by car the next time? in my opinion watching the front sight is more important than how the parts where made. I have a Kimber sst compact with over 5,000 rounds through it without anything breaking which I can't say the same with the two Colts with a lot less rounds that I used to own.

 

[JohnBT]

I googled up this history from a medical device site:

"While MIM is certainly a new technology when compared with traditional metalworking processes, it has been a commercial reality for about 25 years. During that time, the technology has spawned an industry that is now international in scope. The Metal Injection Molding Association (MIMA) was formed in 1987, under the auspices of the Metal Powder Industries Federation (MPIF); current membership includes representatives from six countries. In 1993, a guide to specifying MIM materials, "Materials Standards for Metal Injection Molded Parts," was published and is available from MPIF."

Of course, this history doesn't account for parts made by casting or sintering.

JT

 

[KurtC]

Smith & Wesson began in 1997.

 

[Lone_Gunman]

I am not so worried about MIM parts breaking as I am about certain MIM parts simply functioning right in the first place.

Specifically I think the extractor on a 1911 is an example of this. I think MIM extractors work poorly. They don't have the same ability to maintain tension, and seem less likely to consistently extract, in my opinion.

I really havent had problems with any MIM parts, except for 1911 extractors.

 

[Old Fuff]

I think the issue revolves around two points:

First - Regardless of the technology, when a part is designed to take advantage of the fabricating method’s strengths, and avoid its weaknesses, that part will probably work well. However if an alternative technology is substituted to simply duplicate a part originally made out of different material, heat treating, inc. that part may exhibit problems because the weakness of the alternative method haven’t been taken into consideration in that particular application.

Within the firearms industry, the substitution of new, in place of traditional manufacturing technologies, has almost exclusively been driven by the desire to lower manufacturing costs, and sometimes little interest has been expended to insure that the resulting parts will be functionally equivalent to the older ones.

A good example is the internal extractor in a 1911 pistol. Browning designed it to be a leaf spring, and specified a spring steel alloy, that would be heat treated and then spring tempered. A MIM extractor may look the same, but it can’t be spring tempered.

Another one is Springfield Armory’s hopefully short time use of a MIM hammer strut. They lacked the structural strength to stand up to the stresses, and as a result sometimes snapped in half. When this happened the pistol was completely disabled, and could not be used until that part was replaced. This is not reassuring to a person who might be carry this pistol as a personal weapon.

The second point is quality control, or the lack of it. Regardless of the fabricating method, garbage in is still garbage out. When the primary driving force is cost saving, and most if not all of the parts are being purchased from vendors, the lowest bidder often gets the business. Others may do as they wish, but the Old Fuff prefers to not stake his neck on something made out of parts submitted by a low bidder, especially when the gun manufacturer seems to have a questionable quality control department of their own.

 

[MadMercS55]

As already said, MIM parts aren't really bad per se. Some parts are fine when made that way, others required different means. I have some newer SIGs and have been told some of the parts are MIM, but I have had no problems. On the other hand I know many Kimber owners that have small-parts failures. It depends on the part, it's application and very much on the company's quality control. Avoiding MIM is probably hard these days given modern production methods.

 

[Third_Rail]

Let me be another to join in with saying "MIM parts aren't bad". Not a higher failure rate than cast parts (which would be used, not milled parts).

 

[45auto]

Remington has being using MIM for a long time now.

I believe they have their own seperate division and do contract work in MIM also.

 

[Walt Sherrill]

A RUGER seems to be one of the industry leaders in perfecting the process. One of their subsidiary companies is the primary provider of MIM parts for most major gun makers.

 

[Kruzr]

Remington was the first firearms company to use any kind of powdered metal technology for gun parts. They began in the 1950's. They patented their own MIM process in the early 80's.

I know that Ruger is one of the top companies in the world for investment casting but I don't believe they have any MIM companies.

 

[Walt Sherrill]

I know that Ruger is one of the top companies in the world for investment casting but I don't believe they have any MIM companies.

They may not be separate companies (although I think that might be the case with Pine Tree), they do work for other gunmakers and other industries as PINE TREE CASTINGS in NH, and RUGER INVESTMENT CASTING, in AZ. They probably produce as much or more revenue from these parts of the larger Ruger organization than the do from gun sales. The Pine Tree facility is over 250,000 square feet, and the Prescott site is larger (300,000 sq feet.)

http://www.ruger-firearms.com/Casting/Facilities-Intro.html

 

[mec]

This guy's Kimber hammer crumbled apart in mid-use

Crumbly metal has been around for a long time. I suppose sintered metal isn t the same as MIM-just evokes the same ugly feeling. In the 60s, we heard Ruger was using it on the blackhawks and Dan Wesson was using it on action parts. May or may not have been true.

 

[JohnKSa]

Much like any manufacturing process, when it's done right it's a non-issue. When it's done wrong, it's a problem.

 

[gudel]

apparently certain mfr's can't get it right. don't know why people still buying it.

 

[HammerBite]

JohnBT and KurtC . . .

Thank you for responding to the question I asked. Your answers are in accord with others I have gotten from different forums and various gunsmiths, so I consider the questioned to be satisfactorily answered for my purposes.

Thanks again.

 

[HammerBite]

Old Fuff . . .

Thank you for your succinct analysis of the situation within the firearms industry. It seems to me that you are on target.

 

[EddieCoyle]

It seems to me that you are on target.

That's Old Fuff in a nutshell.


Let me chime in late on this subject. First of all, I'm a member of MPIF and have been involved in MIM since the early 1980's. I'm also a longtime member of PMA (Precision Metalforming Association), and AMT (Association for Manufacturing Technology).

Like others have said here before, when done right, MIM is a perfectly acceptable technology for many applications. Unfortunately, an 1911 extractor is definitely not one of those applications.

MIM is sort of an offshoot of powdered metal (PM) technology. Some people erroneously call powdered metal "sintered" metal. Sintering a step in the PM process.

To make powdered metal parts, a metal powder mixed with a dry binder is compressed under very high pressure - we're talking 10's or 100's of tons of force. The resulting part -called a "green" part at that point, looks like a finished part but it only stays together because of the binder. You can take a green powdered metal part and crush it underfoot back into powder. The green parts are handled carefully and placed into a sintering furnace. During sintering, the binder is "cooked" out and the powder fuses togther to form the finished part. The part is almost (96% or so) as dense as a cast, forged, or machined part. There may be other secondary processes (like forging or machining) done to the part. PM parts can be made very strong - connecting rods for high performance engines are made this way. Not all parts can be made using PM however. The part profile has to be such that it can be pressed into, and pop out of, a mold along one axis. PM molds (called cavities) don't open side-to-side, they open up and down. For example, you can make a gear out of PM, but you can't make a firearm frame.

MIM is like a cross between plastic injection molding and PM. With MIM, a press that is very similar to a plastic injection molding press is used (A PM press is more like a metal stamping press). Metal, along with a heated binder that liquifies is injected into a mold. The resulting part is then sintered. MIM parts are not as dense as PM parts because they are not formed under nearly as high a pressure. MIM parts can be made with more complex profiles that would be impossible with PM. MIM parts are not as strong.

Both processes can be extremely cost effective - they both produce near net-shape parts without costly machining. However neither process should be used to make parts that have to be springy. These processes are more similar to casting than they are machining or forging.

Sorry to go on so long. If somebody wants, we can start a thread on investment casting, forging, and my favorite - STAMPING.

 

[HammerBite]

Sorry to go on so long.

Don't be sorry. That was good stuff.

Metal, along with a heated binder that liquifies is injected into a mold.

That brings a question about MIM metallurgy to mind:

Do MIM parts have a grain structure similar to the way forged parts have a grain structure, and, if so, can injecting the material into a complex mold compromise the predictability of the resultant grain structure?

 

[czhen]

deep breath

Thanks Eddie, good report.
I wonder that for months.

CZ hen

 

[EddieCoyle]

Do MIM parts have a grain structure similar to the way forged parts have a grain structure, and, if so, can injecting the material into a complex mold compromise the predictability of the resultant grain structure?

No they don't. Not like forged parts.