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would this be a candidate for High Speed machining?

Azoth

Aluminum
Joined
May 10, 2019
Location
Houston, TX
KIMG3586.JPG

15" OD and 2.5" thick 4130 226 HBW, most of it gets machined off. They've always went with High Feed, but once there's about .200" left in Z, the brim (like a hat) starts flexing down away from the feed mill and starts breaking inserts. To prevent breaking my inserts I send it home after every pass for the last 6 passes and hammer the brim down.

I'd prefer a cnc machine to run doors-closed so I thought this could be avoided taking it with an endmill at full depth instead. I just don't know if the workholding would be considered rigid enough or if an endmill could last that long because it's a lot of material coming off.
 
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Yep. Send it.
But use a good end mill with a corner rad.
Sandvik Duramill WK-II-LX-50750-R030
530SFPM
.0075ipt
Full depth
5%stepover.

If you're unsure, just take in 2 depth cuts.
 
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Could you support the brim so it won't flex down ?
Idk I think I'd end up machining the support because I need to machine deeper than the thickness so the feed mill doesn't leave material.

If I used a shoulder mill instead, I wouldn't have the problem. But then why not just high speed the whole thing (if endmills are cost effective)
 
Yep. Send it.
But use a good end mill with a corner rad.
Sandvik Duramill WK-II-LX-50750-R030
530SFPM
.0075ipt
Full depth
5%stepover.

If you're unsure, just take in 2 depth cuts.
Any idea how many parts you could get? About 300 cubic inches to remove from ~440 to 140
 
Any idea how many parts you could get? About 300 cubic inches to remove from ~440 to 140
That depends on how you're holding the endmill and runout. Shrink fit? Hydraulic? Side lock?
Coolant or dry?
Obviously you want zero runout, so in a perfect world I'd say at least half a dozen parts or more. Could be a dozen.
But the first thing I'd do is a dummy toolpath with that tool and an HSM path with whatever parameters you can run it at and compare the time difference.
If the HFM is much faster, then I'd just use that until you get down to the problem area with the brim, then pop in an end mill and cut that off with 1 cut (full diameter).

That might be the way to go depending on cycle time between the 2 paths.
 
A 3/4 end mill with 2-3/4 or better flute length will run you at least $300.
Harvey has one for $307, that Sandvik one above is $288 after our discount. So if you don't get the Sandvik discount then I'd go with the Helical.

How long is it taking with the HFM?

https://www.helicaltool.com/products/tool-details-81880
I didn't mean cost effective as in run time, but in tool life. They're not going to go for it if it's 1 endmill per part.

Not sure about run time. Last time I ran it I left a note in the program, 1.83 hrs ea. So maybe 1 hour on the feedmill. I can probably get 2-3 parts per corner (3 side 5 insert) unless I start popping inserts because I didn't take a hammer to sharp metal.

So it's like $30 per part for feedmill inserts.
 
That depends on how you're holding the endmill and runout. Shrink fit? Hydraulic? Side lock?
Coolant or dry?
Obviously you want zero runout, so in a perfect world I'd say at least half a dozen parts or more. Could be a dozen.
But the first thing I'd do is a dummy toolpath with that tool and an HSM path with whatever parameters you can run it at and compare the time difference.
If the HFM is much faster, then I'd just use that until you get down to the problem area with the brim, then pop in an end mill and cut that off with 1 cut (full diameter).

That might be the way to go depending on cycle time between the 2 paths.
.002" TIR is common for the tools here. Mostly using side lock. Sometimes .001 with ER collets.

"1 cut at full diameter"
Are you saying to slot the brim and let it fall?

I do that already with the high feed mill, but those push downward. I've considered letting my finish endmill take it like you said, but I didn't want the drop flying around or pinching the endmill.

KIMG3588.JPG
 
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I did a quick mockup of the part in your OP and did a HSM path.
I get around 38 minutes.
Are you saying to slot the brim and let it fall?
Yes.
But maybe cut it off in sections, like take a cut along the left side, then front, back and right so you end up with 4 pcs of the brim. Maybe with a 1/2" end mill.
 
.002" TIR is common for the tools here. Mostly using side lock. Sometimes .001 with ER collets.

"1 cut at full diameter"
Are you saying to slot the brim and let it fall?

I do that already with the high feed mill, but those push downward. I've considered letting my finish endmill take it like you said, but I didn't want the drop flying around.

View attachment 412113
yeah .002" runout will fuck your tool life up. with a light enough radial cut, your work holding shouldnt be an issue.
check out Fraisa MFC endmills as well, really good in tough steels. you'll want shrink fit or milling chuck for it. ER will pull out and side lock is too much runout.
 
Yeah then it's probably not worth it to buy a $300 end mill lol.
Unless boss likes the time saved and thinks it's beneficial.
I just don't want to flay my hand open beating on it with a hammer. I do put on thick impact padded gloves, but still
KIMG3590.JPG
 
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Once you get to about .200 thick (or thicker, just to be safe), just put some old long endmill in it and full slot it to cut the brim off.

And I do mean any old long tool, not your finisher. Even a cobalt rougher or something that can take the flimsy vibrations without chipping and snapping.
 
Instead of using an expensive 3/4 tool for all your roughing you could do 90% of your roughing with a cheap 1/2" tool taking 2 depth cuts, and leaving clearance for the holder on the second depth cut. Just a little bit of stock left then to get then with that expensive 3/4 tool.

I also like the idea of using a feed mill to do most and then cut brim with endmill.

We use sandvik R390 cutters in steel fairly often too. Can ramp down to a depth where you think the brim is getting a bit thin, then do a single contour taking the entire brim away in one pass. Move in an repeat.
 








 
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