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aluminum end mill, wet or dry? what coating? what supplier?

BT Fabrication

Stainless
Joined
Nov 3, 2019
So been having an issue ramping down cut into aluminum, and in the corners it occasionally chips a tooth at the end of a 1/2" wide slot.
running it dry and just air blast.
What does everyone else use for coatings, coolant or no coolant, specific brands of end mills that have worked well.?

the slot is just a through slot in 1/2" thick aluminum and ramping spiral slotting in a 1" long slot x 1/2" wide, just wondering if my angle (2 degrees)into the material wasn't deep enough as it was trying to roll aluminum in front of the cutter. was getting vibration at higher speeds, so i was running it at 3000rpm which might be a little fast for the 18.8 IPM and about 0.0032 per tooth 3/8" 3 flute uncoated
im thinking it might be rubbing a bit, but not 100% sure.
endmill specs were about 5600rpm at 37.6IPM in slotting.
only thing I know was that at 3300 RPM it was worse and increasing feed didn't help.
next thing i can think is drop rpms lower to get a thicker chip
 

apoet

Plastic
Joined
Dec 10, 2021
Use flood coolant if you have it. I'm assuming you are using a carbide tool, so coating really shouldn't matter. Is the setup rigid? I'd turn the rpm way up. Your ~.003 chipload seems reasonable to me, along with your ramp angle
 

Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington
So been having an issue ramping down cut into aluminum, and in the corners it occasionally chips a tooth at the end of a 1/2" wide slot.
running it dry and just air blast.
What does everyone else use for coatings, coolant or no coolant, specific brands of end mills that have worked well.?

the slot is just a through slot in 1/2" thick aluminum and ramping spiral slotting in a 1" long slot x 1/2" wide, just wondering if my angle (2 degrees)into the material wasn't deep enough as it was trying to roll aluminum in front of the cutter. was getting vibration at higher speeds, so i was running it at 3000rpm which might be a little fast for the 18.8 IPM and about 0.0032 per tooth 3/8" 3 flute uncoated
im thinking it might be rubbing a bit, but not 100% sure.
endmill specs were about 5600rpm at 37.6IPM in slotting.
only thing I know was that at 3300 RPM it was worse and increasing feed didn't help.
next thing i can think is drop rpms lower to get a thicker chip
No coating for finisher.
ZrN, or Destiny's "Stealth", or nothing, for roughers.
Definitely coolant, lots and lots of coolant. Firehose stream right into the cut if possible.

Without coolant, I think you are going to fight BUE and completely clogged flutes, even with a good coating.

Regards.

Mike
 
Last edited:

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
If it's 7075 aluminum, then you can get away with no coolant for the most part since it's harder than 6061.
But for 6061 I always use coolant, period.
As for chipping the end mill corners, it could be a couple of different factors really.
3000 rpm and 18.8 ipm is .002" ipt which seems ok, but I would double or even triple the rpm's if you can.
Typically we use bright finish end mills for aluminum. And if you're having chipping issues on a thru slot you can either use a bullnose or use a drill for a start hole then plunge into the hole and slot away.

As for the 2 degree ramp, the 3 flute should be capable of a much larger ramp angle. Heck you can even plunge with it.
 

BT Fabrication

Stainless
Joined
Nov 3, 2019
Use flood coolant if you have it. I'm assuming you are using a carbide tool, so coating really shouldn't matter. Is the setup rigid? I'd turn the rpm way up. Your ~.003 chipload seems reasonable to me, along with your ramp angle
I have coolant, but not yet setup on this machine I just got. Had to fix a few things on it first before adding coolant and parts don't show till november...
 

BT Fabrication

Stainless
Joined
Nov 3, 2019
If it's 7075 aluminum, then you can get away with no coolant for the most part since it's harder than 6061.
But for 6061 I always use coolant, period.
As for chipping the end mill corners, it could be a couple of different factors really.
3000 rpm and 18.8 ipm is .002" ipt which seems ok, but I would double or even triple the rpm's if you can.
Typically we use bright finish end mills for aluminum. And if you're having chipping issues on a thru slot you can either use a bullnose or use a drill for a start hole then plunge into the hole and slot away.

As for the 2 degree ramp, the 3 flute should be capable of a much larger ramp angle. Heck you can even plunge with it.
yep its just 6061.
tried to increase it to 4000 and just destroyed it even faster on the first step down.
its a bright polished end mill and 45 degree helix and sharp corner, might switch to a 0.030rad if i can.
had it plunge at first, ya got about half way, clogged up and snapped it off in the holder.
 

BT Fabrication

Stainless
Joined
Nov 3, 2019
for the lolz
ive scoured the web from a ton of suppliers, all the way from maritool,yg, iscar, widin etc to any information/research or articles. i could find from tooling suppliers. so not like i haven't tried. not really wanting to keep breaking $50+ endmills off when it could be something simple I'm overlooking. the breakage isn't consistent either.
 

Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington
ive scoured the web from a ton of suppliers, all the way from maritool,yg, iscar, widin etc to any information/research or articles. i could find from tooling suppliers. so not like i haven't tried. not really wanting to keep breaking $50+ endmills off when it could be something simple I'm overlooking. the breakage isn't consistent either.
Coolant. You have to use coolant. Otherwise the flutes will clog up and the tool will snap.
 

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
not really wanting to keep breaking $50+ endmills off when it could be something simple I'm overlooking

How much is the tool sticking out from the holder? And is it chattering?
Even dry it shouldn't be chipping the edges unless you're getting edge buildup.
 








 
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