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How fast (SFM) can you run HSS in 6061?

Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington
I'm running a Whitney 5/32" bullnose cutter in 6061 to put a bullnose all the way around a ~5" x 20" part. I actually don't know what the practical limits are for HSS cutting 6061. I'm running 1,300 SFM right now, and all seems well. I'd like to go faster, of course, but I don't want to prematurely dull this expensive cutter. I have several hundred parts to make.

Anybody running HSS in 6061 at "very high" SFM's?

Thanks, and regards.

Mike
 

Conrad Hoffman

Titanium
Joined
May 10, 2009
Location
Canandaigua, NY, USA
I dunno, 1300 SFM seems way high to me. Usually you lose the corners and edges on HSS quite quickly if you go too fast. OTOH, it probably depends on the specific tool quality, coolant and how much crap is in the 6061. As we all well know, not all aluminum is created equal, regardless of what they claim.
 

Philabuster

Diamond
Joined
Jul 12, 2006
Location
Tempe, AZ
Would this Harvey tool work for you or do you need to ask them to modify the dimensions? My opinion, carbide tools are cheap compared to wasting time with HSS.

 

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Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington
Any reason not to run a carbide tool?
The only carbide equivalent I know of is Harvey 32810, but it is only 3/4" diameter and 4 flutes, while the Whitney tool is 1-5/16" diameter and 8 flutes. With scallop height considerations, I probably would have to run the Harvey tool faster than my 16k RPM max to get the same finish as I'm getting with the Whitney tool.

If there was a larger diameter high-flute carbide or carbide-tipped cutter out there, I'd be interested.

Regards.
 

jaguar36

Cast Iron
Joined
May 13, 2015
Location
SE, PA
I've always tried to run HSS at around 600 SFM. My understanding was that gave the best compromise of cutting speed and tool life. I imagine that it does vary based on what flavor of HSS you're using though.

I don't see an HSS cutter making it through all those parts regardless though, so I'd grab a carbide one and let er rip. Can always get a custom one made if needed, they aren't really that expensive.
 

Philabuster

Diamond
Joined
Jul 12, 2006
Location
Tempe, AZ
The only carbide equivalent I know of is Harvey 32810, but it is only 3/4" diameter and 4 flutes, while the Whitney tool is 1-5/16" diameter and 8 flutes. With scallop height considerations, I probably would have to run the Harvey tool faster than my 16k RPM max to get the same finish as I'm getting with the Whitney tool.

If there was a larger diameter high-flute carbide or carbide-tipped cutter out there, I'd be interested.

Regards.
Got it.

Looks like Whitney makes a carbide tipped version with 6 flutes but currently backordered on MSC.


McMaster has a 6 flute 1" HSS cutter on the shelf for $145 if you do end up dulling out your current cutter before you finish your parts.

 

MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
I always just have my endmill guys pop a radius on something off the shelf if I need an odd one.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
I'd like to hear an update about this when you're done to see how long it makes it. It sounds like you are only nipping the corners? Is that a convex corner rounding cutter then? That should allow you to push the speed up pretty good, but I wouldn't have expected 1,300+ SFM.
 

Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington
I'd like to hear an update about this when you're done to see how long it makes it. It sounds like you are only nipping the corners? Is that a convex corner rounding cutter then? That should allow you to push the speed up pretty good, but I wouldn't have expected 1,300+ SFM.
The previous operations leave a 6mm thick square edge with .01" extra, so yes, the bullnose isn't removing a lot of metal.

Regards.

Mike
 
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rogertoolmaker

Cast Iron
Joined
Jan 3, 2016
I dunno, 1300 SFM seems way high to me. Usually you lose the corners and edges on HSS quite quickly if you go too fast. OTOH, it probably depends on the specific tool quality, coolant and how much crap is in the 6061. As we all well know, not all aluminum is created equal, regardless of what they claim.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
I've run large (.75R) HSS corner rounds and 3" HSS slitting saws at obscene SFM and they seem to hold up great with lots of coolant in 6061.
 

rogertoolmaker

Cast Iron
Joined
Jan 3, 2016
I agree the 1300SFM is way high. Shops seems to have a love for 6061T6 which is not the best aluminum for machining. It is used for extruded parts and as such is mealy and has a tendency to stick to cutting edges.
 








 
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