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Turning Flame cut edges

ben04

Plastic
Joined
Jun 8, 2019
Hi all, I'm after some advice or info, I have a Ø580 x 140 Flame cut mild steel bit of metal. I'm turning it on a Mazak quick turn 400-ii using an iscar 6025 CNMG for the roughing 0.8 rad (tried 907 grade too, doesn't last as long)and the flame cut edges are wearing the tips out rather fast.
The first cut is around a 2-3 mm depth of cut to get under the skin at 160mm/min at a .35 feed rate, are there any more suitable tips available to deal with the flame cut edges.
Thanks

IMG_20190608_063358.jpg
 
If you're using a CNMG insert you're likely using it in an MCLN toolholder (Pic 2) which makes the point of
the insert lead in the cut. On tough cuts like that I've had good luck using an MCRN toolholder which uses
the less acute angle of the insert and puts it in a trailing position (Pic 1). Seems to get under the hard stuff
better...

(Sorry but the images got reversed when they uploaded...)
 

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On tough cuts like that I've had good luck using an MCRN toolholder which uses
the less acute angle of the insert and puts it in a trailing position (Pic 1). Seems to get under the hard stuff
better...

Ill second that suggestion, also try a 1.2mm nose rad. This is how we turn cast impellers (heavy intermittent cutting) with good success.

Then if you are still struggling maybe drop the speed?
 
I think there might actually be one of those holders here, I'll try that and report back. Thanks
 
It would be nice....if you could send them out for steel shot rotoblast.

Heavy rotoblast.
 
I would probably back that speed and feed down on the first cut. Because it is kind of intermittent you should not have too many issuse breaking a chip at a low feed.
Then crank it up for the rest of the roughing. Try 120M/min and lets say about 0.24 feed. Make sure that you really get under that skin so even if you take a 2-4mm per side cut to make sure it does. A CNMG will handle a 4mm per side if everything is dialed in.

Also IC907 is a harder grade and is better suited for stainless (I found some new Walter Titex grades and chip breakers for stainless that kick the 907's with TF chipbreakers butt but cannot remember it off hand. On that subject the Taegutec TT5080 is also pretty damn good in stainless) so you would have better luck with your IC6025 because it is tougher.
 
Turns out I didn't have one of those holders as I thought.
I'll write a new bit of program with Slower speeds and feeds to take the skin off then ramp it back up for the rest of the roughing. By the time it's been faced and od turned most often that tip corner is knackered, hard spots in the material isn't helping either 😐

Paint does certainly dry faster haha!
 
Unfortunately due to the size of the job we have to space all the tooling out at every other tool post so no room for an additional roughing tool, wonderful Mazak design!

In the ideal world an old manual would be perfect to pre turn but we don't have one big enough :/ these things are about ¼ a ton each
 








 
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