Tool Life Regression on Powdered Metal Parts

I wasn't sure where to put this because it's related to machining as well as MIM and BJP, but is fundamentally a powdered metal problem.

I'm working with MIM on Ti 6Al-4V and BJP on both SUS316Li and Ti 6Al-4V. The goal is to make a near-net shape part to reduce machining time and reduce carbon footprint. Independent of material and process, I am seeing serious tool life regression of 25-75% when baselining against forgings or plate. There is little to no literature out there talking about this. Has anyone else experienced this before and what do you know about it?

I was regularly grinding a powder metal broach inset, and when I went on vacation they almost closed the plant, They were ordering expensive ceramic wheels, pink wheels from Radack AND JUST GOING CRAZY. I was out in the bush in Canada and did not know they had gone squash. Ordering rush broach insert kept them running for two weeks. to grind that stuff, I had to literally crash into the part with a heavy grind and lift the whee when the RPS fell. Then go back to crash again. I had to ring a step dimension off the teeth height so about .035 x 1" x 18 or 24 (?}. I think they discontinued using that material, now I cant remember. It made a great cutting tool /broach insert. It was almost as hard as carbide but would not grind with a diamond wheel. The original white AO wheel still proved best after they spent a ton of money on everything else. I think that grinder was 7Hp and for that material 15 or 20 Hp might have done better

I can't imagine maching that stuff but don't know what it is like before heat-treat..

Very interesting observations. We've done some preliminary investigations on machining of additive parts, and I believe this is an item of interest for the cutting tool manufacturers. Assuming you are using one of the big names, it may be worth a call to see if they can provide some insight on optimized tools or cutting parameters.

DillyDilly said:

I wasn't sure where to put this because it's related to machining as well as MIM and BJP, but is fundamentally a powdered metal problem.

I'm working with MIM on Ti 6Al-4V and BJP on both SUS316Li and Ti 6Al-4V. The goal is to make a near-net shape part to reduce machining time and reduce carbon footprint. Independent of material and process, I am seeing serious tool life regression of 25-75% when baselining against forgings or plate. There is little to no literature out there talking about this. Has anyone else experienced this before and what do you know about it?

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Hightemp said:

Very interesting observations. We've done some preliminary investigations on machining of additive parts, and I believe this is an item of interest for the cutting tool manufacturers. Assuming you are using one of the big names, it may be worth a call to see if they can provide some insight on optimized tools or cutting parameters.

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MIM is not printing.

And your having tool life problems in secondary machining of the parts ?
Or of the mold ?

we do powdered metal parts all the time. Tools don't last very long, so you change them. Work it into the price.

I am working with MIM Ti as well as Binder Jet Printing(BJP) on both Ti and SUS. The issue here is cutter life. Tools are just fine.

That's kind of the issue. Agreed, I can change tools 2-4x as often, but when the parts I am trying to make aren't aerospace structural elements it's hard to imagine ever scaling this on a part that should cost $40. When your turbine part costs $10k, blowing an extra $100 on tools is trivial. I appreciate the response though.

The 3D printing industry has been talking about mass production being 2 years away for what feels like 20 years and it's starting to feel like the promise of fusion energy. Most of the focus has been on increasing the throughput of the processing equipment, but if the resulting increase in secondary processing costs negate the savings on the front end, it'll never go anywhere. This appears to be a fundamental material issue.

DillyDilly said:

The 3D printing industry has been talking about mass production being 2 years away for what feels like 20 years and it's starting to feel like the promise of fusion energy.

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I think that sums it up pretty well. The next problem is always right around the corner.

digger doug said:

MIM is not printing.

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No, but Desktop Metal and Markforged's Metal X both use technology similar to MIM.

So users of those systems would probably run into the same issues as the OP.

Larry Dickman said:

we do powdered metal parts all the time. Tools don't last very long, so you change them. Work it into the price.

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.
I have also machined powdered metal parts and found then abrasive on tools. tried different
cutting parameters but ultimately if material is abrasive then tool life is just expected to
be shorter than normal... sudden catastrophic tool failure normally a bigger problem than changing
the tooling more often

I claim no specific expertise, but if I were working those materials my concerns would be atmospheric contamination of the feedstock leading to excess oxides and nitride formation.

You're dealing with fine particles of the raw material which undergo high heat in processing. That means huge surface areas relative to mass, which gives oxygen, nitrogen, and whatever else the opportunity to bind with the metals and be converted during processing into oxides and nitrides.

If the raw stock was stored with an argon shield gas and the process equipment was similarly protected, I'd suspect post-process machining and grinding would be easier, but the cost to implement that might be greater than the excess tooling use.

Any attempts at grinding with CBN?

Orange Vise said:

No, but Desktop Metal and Markforged's Metal X both use technology similar to MIM.

So users of those systems would probably run into the same issues as the OP.

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Yes, but this is a precise business, and requires precision in explaining, to get a precise answer.