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High feed cutters and vertical walls

tcncj

Cast Iron
Joined
Dec 15, 2016
Hi all

I've got a question regarding high feed tools.
They don't like tight corners so I try to prevent that in my CAM toolpaths.
Other thing I came across is that they don't like vertical walls. When fully in the cut they sound nice and smooth
But once they cut next to a wall they make a crunching sound, that doesn't seem right.
I have high feed mills with rectangular and square inserts, but both have this issue.
I'm struggling a bit with it, especially in stainless where chips stick to the walls.
Anyone got an idea what's the cause of this? cutter design? Is there a work around?
 
The cutter has higher engagement at the wall, since the floor will be ramping up matching the edge profile at the wall, so it's a much heavier cut, and defeats the chip thinning design of the high feed cutter.

Some workarounds come to mind:
1. Slow the feed rate of the pass next to the wall.
2. Make a pass with a flat or bull endmill at the wall between Z depths of the high feed.
 
Feed mills do not do walls or shoulders at the same speeds they can fly across things.
Plain and simple and you are not understanding your tooling and how it works and cuts metal.
Why do people try to do this?
(sorry if this a bit abrasive but as a cutting tool vendor I do run into this so many times) :wall:
Add that I'm just a rookie with some time in so maybe my thoughts are poop and a random net guy so maybe not correct or have some bias.
 
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Feed mills do not do walls or shoulders at the same speeds they can fly across things.
Plain and simple and you are not understanding your tooling and how it works and cuts metal.
Why do people try to do this?
(sorry if this a bit abrasive but as a cutting tool vendor I do run into this so many times) :wall:
Add that I'm just a rookie with some time in so maybe my thoughts are poop and a random net guy so maybe not correct or have some bias.
I do understand the concept of high feed mills.
But didn't came to mind the concept doesn't work on vertical walls, like a pocket.

The lack of good toolreps around here who know there stuff doesn't help.

So how do people overcome this? I see a lot of high feed milling of pockets.
I don't believe they can only be used to rough out pockets with a angled wall

Looks like a pocket to me
outside vertical wall:
 
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But once they cut next to a wall they make a crunching sound, that doesn't seem right
Is the shank of the tool contacting the wall? I have a few high feed tools with 1.25" shank that I had to turn down the shank between the cutter up to the point where the shank enters the tool holder.
 
Nah they all run free
Issues starting to happen with a depth over +/- 3mm in the material
 
I just let it make the "crunchy sound" and haven't had noticeable problems. This is with 1/2, 1", and 2" feedmills.

I run a lot of parts with a 3.9" hole in a36 3 inches deep with the 2" feedmill, as well as pockets around the perimeter of the same part 2" deep with the 1" feedmill, never issues, tool life is very long.

I nearly never have problems with the inserts failing at the outside corner when meeting the wall, they always start to break down on the angle or bottom "tip" of the insert, not the outer diameter.



Right now as I type this I'm feedmilling 321 stainless, doing a 1.8" thru hole 1" deep with a 1" feedmill, ~1100rpm 60ipm with a .030 ramp down. It sounds.... kinda horrible, but it's working. I would imagine it would sound better if it wasn't rubbing the wall.



You could try leaving a draft angle on your wall?
 
Luckily I'm not the only one worrying about the "crunchy sound" haha
Yes a draft maybe works.

Toollife is good though. Especially in hardened steel. Where there is almost no "crunchy sound"
But always struggle a bit with high feeding in stainless. Once it's full in the cut it purrs perfect though
 
Luckily I'm not the only one worrying about the "crunchy sound" haha
Yes a draft maybe works.

Toollife is good though. Especially in hardened steel. Where there is almost no "crunchy sound"
But always struggle a bit with high feeding in stainless. Once it's full in the cut it purrs perfect thoug
As you pointed out, the situational sound is the difference of material characteristics. Keep in mind, when you are milling against a wall with a high feed cutter, the insert is completely engaged which is exactly the same condition as dead-heading an end mill into the corner of a pocket so the cutter is completely engaged in the material, with zero interpolation; not the best scenario. Side loads go high as well as spindle loads so you're you may see more deflection as your holder length increases. At least your tool life is good, so the biggest benefit would probably come from using the shortest possible holder and try to stay on top of chip evacuation. When your material is gummy you could try a different insert grade or even MQL if you can find a unit.
 
That crunching was common place until we started running the Kyocera raptor, they fling the chip out forward, makes a huge difference with walls and slots.

 
Some people recommended the kyocera stuff to me.
That crunching was common place until we started running the Kyocera raptor, they fling the chip out forward, makes a huge difference with walls and slots.

Seems like a good recommendation!

At 56 seconds in the video is the issue I have.
 
I had the same thing with Hitachi high feed tools, the chips would actually gall and stick on the steep sidewalls, not with these. Get yourself a demo, you will be impressed.
 
Luckily I'm not the only one worrying about the "crunchy sound" haha
Yes a draft maybe works.
Irrespective of chip recutting, adding a draft is always a good idea with repeated depth cuts. After the crunching goes away, you'll still hear the hammering. Adding a sufficient draft eliminates that as well. Every cut should sound like the first or second depth cut.
 
I always drafted my walls when using a feedmill. I would usually shoot for 2 - 5 degrees depending on how deep you're going. Since a feedmill is only for roughing, come back in with a solid cutting tool to straighten the wall up.
 
I know well that you are not supposed to cut a vertical wall with a high feed cutter at normal high feed chiploads.

However, I have removed many tonnes of material (tens if not hundreds of, and plenty of difficult materials amongst it) doing exactly this over the last two decades that I have been using feedmills, and my experience is that it doesn't really have any significant negative impact on tool life all else being equal. It has not been my experience that the corners fail first as you would expect them to.

If the machine is not stiff enough (in terms of lateral deflection AND torque deflection), or chip evacuation is not good enough, or the setup is not absolutely rigid, THEN it has an effect. If deflection is an issue (usually evidenced by irregular wall finish and sometimes fretting on the toolholder, but also lots of noise when cutting with a small stepover) then you ought to consider if the feedmill you are using is perhaps too big for your machine. 40mm is the largest that I will use willingly on a 40 taper for reference. 66-80 is the sweet spot on a 50 taper. 80+ only if you have LOTS of torque in your spindle or are cutting soft materials.

Yes you will get occasional chip impaction on the wall, and yes you will probably scuff up the shank of your tool/holder. But high feed is for roughing right?

For reference, I really only use Sandvik R210 and Tungaloy DoFeed. I have tried some others and not been impressed, and there are some that I haven't tried at all, like the Kyocera mentioned above. But those two can take some serious punishment and cut vertical walls just fine, as long as everything else is up to it.
 








 
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