Question About MIM Parts Breakage.....

[cslinger]

We always hear about or are up in arms about MIM parts in various 1911s. It seems like there is a new thread weekly complaining about a broken part in a Kimber or something to that effect.

As far as I know other non-1911 style firearms also use MIM parts. In fact I believe SIG uses MIM parts for example. So why don't we hear of the same frequency of breakage. Is it simply a matter of the 1911 selling more units and therefore being more statistically prone to having bad examples?

I am not trying to start a pro or against argument for MIM parts I am just curious.

Chris

 

[Hawk]

My take:

MIM, as a process, does not produce parts inferior to any other process if the part was designed with MIM in mind.

Parts designed in 1908 don't fit that criteria. They likely could, but I don't believe anybody's taken the time, thus they don't work well.

S&W, as example, designed 'em to be "mimable" and nobody whines about their MIM.

 

[The Real Hawkeye]

I think if they are done right, they work fine in 1911s too, for most parts. Parts like the extractor or the firing pin retaining plate, however, really need to be forged steel.

 

[Old Fuff]

Previous posts did pretty well explaining the situation. The 1911 pistol was designed with machined forgings in mind. The SIG/Sauer line was designed after World War Two and went into production around 1970. The parts were designed around modern production methods.

Unfortunately current 1911 makers are trying to hold their production costs down, and in so doing the quality of some parts - regardles of how they are made - has suffered. These makers know that some of the parts will fail, but this doesn't bother them so long as the failure rate is low enough to be seen as a "reasonable cost of doing business." Someone carrying the pistol as a weapon might not see it that way though.

 

[Hawk]

From the Alberox / MAC blurbs:

What Engineers Need to Know to Design for MIM

While many engineers and designers are comfortable in a machining environment, they are often in the dark about metal injection molding, where 90-degree corner angles don't exist. And when they are confronted with flash or ejector pin marks and draft or parting lines, their eyes can easily glaze over. Consequently, MAC urges engineers to brainstorm with them before designing a part.

"Metal injection-molded parts will have about a two-degree draft, so the part will come out of the mold easily," Hill reveals. "Often designers don't allow for draft, excess flash, or even location of the gate; these areas must be considered."

The above is just a bit more specific.

Plus, Old Fuff nailed it. If a part is designed to be "mim-able" it will perform with the best of alternative methods. If an existing machined part is simply handed to a MIM house to save money, the results will be predictable.

 

[NMshooter]

That nasty term "quality control" has something to do with it as well.

The MIM parts in my Kimber, with the exception of the slide stop, have functioned for a very long time with no breakages.

I saw a safety on a newer model break off as the new owner handled the pistol in front of me. Kimber had changed the supplier, and there was a run of bad thumb safeties.

Considering the popularity of Kimber pistols it is not suprising that there would be more complaints regarding those pistols.

When a company starts to cut costs in pursuit of that last fraction of profit you will always see more bad product going out the door.

 

[Bart Noir]

Slightly, but not really O.T. I see in one recent knife magazine (Blade, maybe, can't remember) that Kershaw Knives have started making complete blades using the MIM process. All the fancy angles and grinds are made that way, and the blade just needs a little work to put the final edge on it. And the handle parts, of course.

Bart Noir

 

[TMM]

yup, that was Blade. i get the same mag.