Horge said:
I'd beg to differ!
The company I work for produces wrought refractory metals, and we start with powder. We also produce sintered tungsten alloys; that product and our wrought pure tungsten (99.99%) competes with MIM tungsten that our competition produces. I know we used to supply Ruger with a sintered & machined alloy product, I believe for the 22LR semi-auto rifle, that is now an MIM part.
The MIM products have developed to the point that we are looking into producing it ourselves. As mentioned, cost is a determining factor - but not if quality cannot be maintained - field failures cannot be tolerated.
But - to your point about density - during the sintering process, the binders are burnt off & the part is actually reduced in size. Part of the engineering challenge is to produce the molds to the correct oversized dimensions that will result in a "to tolerance" part after sintering.
This blurb is from Kinetics MIM site (I don't know them - just did a quick search & they popped up):
After molding, green parts are debound and sintered at temperatures up to 2,600°F. During debinding, the polymer binder breaks down and dissipates while the metal particles retain all of the molded features. The metal particles fuse together during sintering and the part shrinks approximately 20% to form a solid metal part.
The process differs from plastic injection molding because of the high heat involved.
I can also say that, at least with pure tungsten which is a very high temperature material, obtaining a density that compares with that of a wrought product that has been rolled down from 2" thick ingot is a challenge. But to the specification issue: there are a few LE agencies that have torture tested guns using MIM parts, & the results were that these guns were chosen for duty work. Clearly, MIM can be used to produce firearm components that sustain the stresses involved.
I'd beg to differ!
The company I work for produces wrought refractory metals, and we start with powder. We also produce sintered tungsten alloys; that product and our wrought pure tungsten (99.99%) competes with MIM tungsten that our competition produces. I know we used to supply Ruger with a sintered & machined alloy product, I believe for the 22LR semi-auto rifle, that is now an MIM part.
The MIM products have developed to the point that we are looking into producing it ourselves. As mentioned, cost is a determining factor - but not if quality cannot be maintained - field failures cannot be tolerated.
But - to your point about density - during the sintering process, the binders are burnt off & the part is actually reduced in size. Part of the engineering challenge is to produce the molds to the correct oversized dimensions that will result in a "to tolerance" part after sintering.
This blurb is from Kinetics MIM site (I don't know them - just did a quick search & they popped up):
After molding, green parts are debound and sintered at temperatures up to 2,600°F. During debinding, the polymer binder breaks down and dissipates while the metal particles retain all of the molded features. The metal particles fuse together during sintering and the part shrinks approximately 20% to form a solid metal part.
The process differs from plastic injection molding because of the high heat involved.
I can also say that, at least with pure tungsten which is a very high temperature material, obtaining a density that compares with that of a wrought product that has been rolled down from 2" thick ingot is a challenge. But to the specification issue: there are a few LE agencies that have torture tested guns using MIM parts, & the results were that these guns were chosen for duty work. Clearly, MIM can be used to produce firearm components that sustain the stresses involved.
Kruz...When ya gonna come for a visit and let an old man teach ya...uh, teach ya...ummmm
