sti faq mim
"gentlemen, the hysteria over mim has been going on for many years. The facts are that mim and pm (powder metal) are modern manufacturing processes that do have their place. Many parts lend themselves to mim processes due to there shape and function. I have been working as a manufacturing engineer and closely with the firearms industry for over 20 years. I can give you some of my experience and facts of mim and pm.
Q are mim parts of lesser quality than cast, forged or barstock?
A no. Mim and pm parts if designed and processed properly are as good as the other process for most small part applications. Design, material selection and heat-treatment processes play a big part in quality and serviceable life of the part. For example, most people don’t understand how many products they use everyday that are mim and pm processed. Items such as the transmission gears in your car, valves, the jaws on the cordless drill you use and many types of carbide tooling for machining to name a few.
Q
why do manufacturers use them in their product?
a quality and cost. Mim and pm allow for consistent process that produces repeatability and good quality parts of complicated geometry. Tooling for mim parts is very expensive and you need to produce a product with some volume in sales or it is very hard to justify the costs.
Q
can you make substandard quality mim parts?
a yes. Again, design and process control are critical to good quality mim parts. But this is also true with cast, forged, or barstock parts. If good manufacturing processes are not followed you will get parts of sub-standard quality.
Q
why do we seem to see more mim parts fail?
a this is pure numbers. Most production firearms include mim or pm parts- yes, you might not want to believe it but most all pistols, revolvers, and rifles contain mim or pm parts. Most people, without knowing the difference, have been using these for many years. Why we hear about it more is because the majority of pistols and revolvers have some mim content in them. So, if we want to look at this logically you have to think in ppm. (ppm is parts per million- it is a basis to how to figure a parts failure rate and its effect on the product.) for example if in 2005 there were 500,000 pistol produced with mim slide stops and the failure rate worked out to be 1 failure per 1000, we would see 500 mim slide stops fail. If in the same year we produced 50,000 with bar stock slide stops with the same failure rate we would hear of 50 failures. So yes, we do hear of more mim failures and we probably should due to the fact that they are, at a minimum, of 10 to 1 in annual sales.
So yes, mim does has its place and it can and does produce high quality and durable parts. Yes, some will fail, just as cast, forged, and barstock parts also fail. I have used 1000’s of sti parts in production 1911’s over the years and the failure rate was basically the same with mim as with the other manufacturing processes. I have worked closely with the people at sti for many years and their designs and process controls are first class. They do not skimp or try to cheapen their product to save a nickel. They use the best processes and materials available and they always have the goal to offer their customers products of exceptional quality and attention to detail."
http://www.stiguns.com/
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