tourchmate cnc plasma cutter and anealing?

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clockworkfish

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Dec 1, 2010
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Hello again everyone, so someday in the future id like to have my own fully equipped shop and ive been thinking about getting a tourchmate 2x2 which is a cnc based plasma cutter for small scale production. i hear that plasma cutting will harden the edge of the cut, and rather than grind that away would it be possible to just anneal the pieces to soften the edges back to a workable state?
 
Using a waterjet service would be a much better idea for several reasons:

1. A plasma cutter will create a ~1/4" Heat Affected Zone where the metal will be basically useless and need to be ground off.
2. If used on air-hardening steels it will harden the HAZ making removing the HAZ more difficult. Most of the higher end tool and stainless steels are air hardening.
3. You will save money by using a waterjet or laser cutting service. Your designs will be cut to exact specs with no HAZ and will remain in the annealed state saving you money on belts.

Lots of very good reading here: http://bit.ly/Y8rcuw
 
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I realize that it creates a heat affected zone, and that's why i wanted to know if annealing would help, i've searched around before but hadn't found any info about it.
i already have my own kiln and am able to heat treat my own stuff.
As for waterjet cutting or laser I do know its fairly cost effective and and accurate, but it will get far more expensive in a hurry when i do batches of 100 at a time. ( yes i realize 100 at a time is ambitious however i think its completely doable assuming a simple design is made)
A torchmate system only runs for around 3 to 5 thousand and the last batch of knives that i had waterjet cut came out to be about 15 a blade, at this rate in 2 or 3 batches i would have already spent about the same amount as the most basic torchmate.

Im just curious as to if the HAZ of plasma cutting is impossible to fix with a proper anneal
 
I think it depends a lot on the steel, from what I've read that might work on simpler steels but on CPM steels it basically destroys all of the benefits you gain from powder metallurgy. Of course I could be wrong, hopefully one of the HT'ing guru's will chime in.
 
I would recommend water jet, laser is good as well and less expensive. I use jet because even laser cutting would require at least a normalizing cycle before HT according to my heat treater. It is appealing to do all the work in your own shop however
 
No body seems to want to answer you, so I will. The haz will only really affect the edge, the rest of the blade doesn't matter if its hardened. Grab a couple carbide reamers or drill bits in the size of your bolt holes and use that to size your holes. Grind the haz off the edge and your good to go.

Don't over think it. I have a buddy doing some work for me with his, its not as big a deal as people seem to think.plus its way cheaper than WJ. Even though I use WJ a lot!
 
jakehobackknives said:
No body seems to want to answer you, so I will. The haz will only really affect the edge, the rest of the blade doesn't matter if its hardened. Grab a couple carbide reamers or drill bits in the size of your bolt holes and use that to size your holes. Grind the haz off the edge and your good to go.

Don't over think it. I have a buddy doing some work for me with his, its not as big a deal as people seem to think.plus its way cheaper than WJ. Even though I use WJ a lot!
Click to expand...

how much material are you removing with the drills and reamers? and so would that mean its only really a concern at the cutting edge? it wouldnt give instability to the entirety of the blade? also is it possible to use a torchmate to do folders? or is that just a bunch of extra work?

Also would a cnc mill for around the same price range be a better buy? less issues with heat, takes a little longer, but the bits might get expensive compared to belts.
 
I really doubt there is going to be much instability with the whole blade. Your going to have to remove some material anyhow so there will only be maybe .125 of hardened area if that. The speeds at which a cnc plasma is cutting with only create a very small haz. I used to cut all my fixed blades with a plasma, it works just fine.

Think of it this way, if you have a .250 haz. The cut is in the middle of that, so you will only have a .125 area that will be a problem. By the time you grind the kerf to make it smooth and parallel it will be 90% gone anyhow.

I wouldn't do folders as you will be needing much closer tolerances for that. WJ is where its at for that.

A cnc mill would be my first choice over a plasma table. But you have to kown what your doing. Your also not going to find a decent cnc mill for less than $10-15000. I bought a old school anilam controled bridgeport from 1983 and it needs work all the time. Still payer 5000 for it.
 
I'd like to clear up a couple of what I see as misunderstandings.

Fist, HAZ won't ruin what makes powdered metallurgy special. At its root it is about fine even carbide distribution which really boils down to even alloy distribution. Alloys (the carbide formers) don't really move much, so even if you completely dissolve carbides and totally saturate the matrix, they still reform in basically the same locations.

Powdered metallurgy steels tend to be very clean, which really won't change. And they tend to arrive in a fine grain structure, which is not an inherent property of powdered metal, but is a reflection of the quality of the subsequent processing. This leads me to my second point.

The primary concern about the HAS isn't the hardening and the subsequent need to anneal. It is the extreme grain growth due to the molten temperatures adjacent to the cut. You can anneal the steel to make it workable, but unless you perform grain refinement (which can be a time consuming non-trivial operation) the HAZ from plasma damages the steel some distance from the cut. I would be suspicious of the first 1/8", though it is a function of the cut speed and steel thickness.

In my opinion, the money "saved" doing it yourself with plasma is false economy. You can get a lot of work waterjet for the cost of a CNC plasma machine.
 
I've not gotten a lot of work waterjet, but my limited experience with it leads me to think that maybe you should shop around more for prices- $15/blade sounds like a bit much unless they are enormous blades.

Did you try requesting a quote from Southland Waterjet? They were good to me... you can mail them a CAD file to save money.
 
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