Metal Injection Molding Blades 440C-Nb

tiguy7 said:
I am not sure what you’re referring to as PM. If it’s powdered metallurgy blades, MIM blades are not stronger and tougher than “CPM” blades.
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Yes and no. CPM process steels used in knives have been processed into sheet and bar stock by hot or cold rolling after sintering, which lowers the porosity and is technically a forging process, introducing grain flow. Compared to unrolled PM steel parts, MIM is stronger. But with knives you're using an additional intermediary step while in the other you're directly forming the finished part without additional processing. One could, in theory, use MIM to create a very strong pre-forging blank of a complex part and then forge it the rest of the way to shape from that and end up with a very strong forged product that would exhibit grain flow.

In a standard PM process all of the fusion that occurs is during the compaction stage, while in MIM sintering is also performed. Density of a PM part without any further processing is roughly 85-92% that of a forged or machined part, while the sintering of the MIM process allows it to achieve even as high as 99% of the density of a forged or machined part, though 98% is more typical.
 
FortyTwoBlades said:
Yes and no. CPM process steels used in knives have been processed into sheet and bar stock by hot or cold rolling after sintering, which lowers the porosity and is technically a forging process, introducing grain flow. Compared to unrolled PM steel parts, MIM is stronger. But with knives you're using an additional intermediary step while in the other you're directly forming the finished part without additional processing. One could, in theory, use MIM to create a very strong pre-forging blank of a complex part and then forge it the rest of the way to shape from that and end up with a very strong forged product that would exhibit grain flow.

In a standard PM process all of the fusion that occurs is during the compaction stage, while in MIM sintering is also performed. Density of a PM part without any further processing is roughly 85-92% that of a forged or machined part, while the sintering of the MIM process allows it to achieve even as high as 99% of the density of a forged or machined part, though 98% is more typical.
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Well that is pretty badass. I haven't been able to find any reference of the tech to make a blade other than that Kershaw Offset. Do you think we'll ever see this in greater use or is it basically a novelty in this case?
 
FortyTwoBlades said:
Yes and no. CPM process steels used in knives have been processed into sheet and bar stock by hot or cold rolling after sintering, which lowers the porosity and is technically a forging process, introducing grain flow. Compared to unrolled PM steel parts, MIM is stronger. But with knives you're using an additional intermediary step while in the other you're directly forming the finished part without additional processing. One could, in theory, use MIM to create a very strong pre-forging blank of a complex part and then forge it the rest of the way to shape from that and end up with a very strong forged product that would exhibit grain flow.

In a standard PM process all of the fusion that occurs is during the compaction stage, while in MIM sintering is also performed. Density of a PM part without any further processing is roughly 85-92% that of a forged or machined part, while the sintering of the MIM process allows it to achieve even as high as 99% of the density of a forged or machined part, though 98% is more typical.
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I never assumed that CPM blade blanks were not rolled. I’ve got 30, 35, 60, 90, 110, and 125 blades. None have ever come up short in the strong and/or tough categories. I never tried an MIM blade because I prefer Vanadium over sculpture. I do have many Boye BDC blades, and they are excellent.
 
tiguy7 said:
I am not sure what you’re referring to as PM. If it’s powdered metallurgy blades, MIM blades are not stronger and tougher than “CPM” blades.
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Just to clarify, "CPM" is manufacturer specific, "Crucible Powder Metal", but there are many many other manufacturers not named Crucible that also make their own standard & proprietary PM steels...
 
strategy9 said:
Just to clarify, "CPM" is manufacturer specific, "Crucible Powder Metal", but there are many many other manufacturers not named Crucible that also make their own standard & proprietary PM steels...
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That’s why I said I wasn’t sure what fixall meant by PM.
 
The structure shown I think would result in fairly weak steel. I'm surprised with Nb amount at 3% - that is quite high
Perhaps @Larrin would speak to this micrograph? ... the grain structure when it's all connected like that (plate martensite?) could result in cracks along the lines?

IMG-20200319-075254.jpg
 
W. Anderson said:
Well that is pretty badass. I haven't been able to find any reference of the tech to make a blade other than that Kershaw Offset. Do you think we'll ever see this in greater use or is it basically a novelty in this case?
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Probably not for common knives simply because the overwhelming majority of knives have very simple forms compared to the kind of parts the method is usually used for.

1*qeizTRihsAPHd7F47Nwkqw.png


From what I can tell, Hardcore Hammers hammers and axes are MIM. They're cast in any case, and while I dislike most of their designs for a number of reasons, they nevertheless seem to have no problems with durability.
 
New technologies are always interesting and it is nice to have options for different applications.
Personally, when it comes to a thin bevel on a knife, I will prefer not to have 1-2% voids...
 
FortyTwoBlades FortyTwoBlades : Thanks for the clarification.

But I wasn't trying to be proper. In an effort to educate, I gave the key word, and in reading up on that, the reader would be exposed to other parts of the process, thus gaining a better understanding. If they actually read that far. If someone does, I've done my job.

But, as a gun enthusiast as well, I can say with some authority that MIM is still a four letter word to many. And powder metallurgy is still a mystery for some. Although the processes are not remotely similar, powder metallurgy steels are actually more akin to a high alloy wootz. From where I am sitting...
 
If I have a choice in MIM of nonMIM parts, I'd choose nonMIM, specifically for a knife, but for guns also. With that said, most gun manufacturers use MIM parts in rheir guns these days with outstanding results. Glock, Sig, Colt, S&W, Kimber, Etc, etc.
 
Boxer .45 said:
If I have a choice in MIM of nonMIM parts, I'd choose nonMIM, specifically for a knife, but for guns also. With that said, most gun manufacturers use MIM parts in rheir guns these days with outstanding results. Glock, Sig, Colt, S&W, Kimber, Etc, etc.
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Specifically, research I've seen indicates that while there were some problems with early MIM firearms parts, the stresses that some of them are subjected to can actually make properly-done MIM stronger than forged parts for the application because of the lack of grain flow. Grain flow in a forged part is a lot like wood grain in that it makes a part strong in one axis but comparatively weak in the other, and while the grain flow produced by forging in a tool like a knife is generally in such a way that strength is improved by its presence, the stresses on firearms parts can actually go in the weak axis of grain flow in forged components at times, and the lack of grain flow in a MIM part makes it equally strong in every direction, allowing it to hold up better under those circumstances.
 
If some designers, are on this forum. I would be pleased to get in contact.

Attached you see industrial blade, out of Mim, without any modification, and it cuts.
I have in my mind to produce blades, with air core inside, but still thin. This technology allows to produce 0.005 Micron, thick layers or walls. Tolerance is 0.2% on size. So as soon we managed the mold, we can produce.
Attached part will cost, 0.5 usd with mim technology. CNC milling, might be difficult...

Video: https://streamable.com/tks31

sqqgw346.jpg
 
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