Cutting out blanks with CNC Plasma router ?

Kosa_PL

Kosa_PL

Joined
Aug 25, 2013
Messages
1,220
Hello guys,

From some time I thinking about to build a small CNC wet plasma routerm to cutting out blanks.

1000mm x 1000mm work area.
1-10mm cutting thickness.

In this year I want go 50% into midtech knives with plasma router and small 700x300mm CNC Router mill :)
If Plasma will be properly set, this will be no difference between Plasma and Laser?

What do you think about cutting out blanks with plasma ?

Best Regards,
Konrad
 
Would thermal cycling/normalizing the blanks after cutting with plasma, laser or EDM cure those problems other than having grind away a little bit of the edge to get rid of any decarbed steel?
 
About this plasma cutter I think to make this cut under 5-10mm of water.
To prevent overheating of the blank. And to have less mess :P

CNC mill will take out that overheatend/hardened zone, and on plasma I will be cutting with 0,3mm reserve.
 
I just bought a really nice small plasma cutter and from the first cut I have been wondering why these are not more popular with knife makers. The haz zone is very small and will disappear when you heat treat any way. The only time I think the haz could cause a problem is if you where cutting your edge bevels with a file. But if your using a file for edge bevels I don't think your going to be buying a plasma for cutting out blanks. I read a good pdf the other day on haz and thy did tests on the area around the cuts and basically the verdict is the heat affected zone is just heated metal besides a very thin oxide skin that really is not very deep and removes quickly with a quick zap on a belt.
 
And when we have CNC Mill ( router type) with CNC Plasma, we have a very nice stuff for cutting out blanks and scales perfectly fitted :D
 
The way I look at it is like such. On stock removal blades I'm going to be removing the metal with a bandsaw or grinder and a plasma is WAY faster then both of those and it can trace a template. But I really like the idea of an XY table for a plasma.
 
I read a good pdf the other day on haz and thy did tests on the area around the cuts and basically the verdict is the heat affected zone is just heated metal besides a very thin oxide skin that really is not very deep and removes quickly with a quick zap on a belt.
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That seems about right, to me. I have done a LOT of work over the last few years with CNC plasma cut steel in my fabrication profession- and there is just a very thin skin of hard oxide on the kerf. After that it's just steel, if heat affected that will be corrected by cycling and quenching anyway.
 
From what I have seen, even EDM cutting "underwater" (which is redundant) leave a very thin HAZ, like maybe 10-15 thousandths.
 
You could have issues with grain growth near the cut that could cause sensitivity to crack propagation if not removed. Your heat treat generally won't reduce this. It may be a very thin skin, but I don't see any way the material directly adjacent to the cut wouldn't have been over heated.

I use a plasma all the time to break down 24X36 sheets to fit into a big bandsaw, but I wouldn't be comfortable with a HAZ near the finished part. I'd want at least 1/16" to be safe.
 
As I mentioned before, CNC Mill will cut out that overheated portion with good quality carbide endmill :)
 
Kosa_PL said:
As I mentioned before, CNC Mill will cut out that overheated portion with good quality carbide endmill :)
Click to expand...

Right :thumbup:

You'll want to conventional mill that for your rough pass rather than climb so the cutter just bends the hard layer out into a ribbon rather than cutting it into chips
 
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