spindle load in alum for different cutters

[mls]

I am playing with different methods of removing alum efficiently. I tried a 1 inch insert mill 4 flute and a .5 accupro 3 flute carbide alum millthe .5 mill seems to be the better choice. My machhine is a 2006 haas vf 3 20 hp 7500rpm with gearbox at 7500 rpm .350deep and 40% tool engagement at 180ipm seems to load the spindle more than if I run this a little slower 6750 rpm seems better does this this sound correct. I use these speeds and feeds a lot I have the hs pocketing with bobcad is there a better way that other people would like to share.

Also I also have a 2001 haas mini millIt seems to like the .375 mills the best I dont try to bury the load meter and this only has 6000rpm.

Thank You for any help Mike

[anemachinebc]

I have the same machine here at work and i can bog it down with a 1/2 roughing mill. I really really have a problem with HAAS machines, for the money you cant beat them, but i think they are junk. Yea it has a gear box but the high range is 1:1.125 its over driven, this kills the torque. Also 20 HP in a HAAS means its a 10HP motor that they jack twice the ammount of juice to it to double the power. I just run the cutters slow on this machine as it doesnt have the speed or power required to run a cutter efficiently. On our bigger horizontals i run a 1/2 rougher at 10,000RPM .3 down, 60% engagement, at 150ipm, this works really good. VF3 somewhere around 7500 rpm i think 80 ipm, anything more boggs these things down.

[Geof]

Originally Posted by mls .....7500rpm with gearbox at 7500 rpm .350deep and 40% tool engagement at 180ipm seems to load the spindle more than if I run this a little slower 6750 rpm seems better does this this sound correct.....

Yes. I have observed this on several Haas machines and it is related to the motor torque. At top speed the torque has dropped down so as you reduce speed you are increasing torque so the motor does not have to work as hard. Of course you are also increasing the chip load so if you keep on reducing the rpm eventually you will get to a point where the spindle load starts going back up. I have found that often a sweet spot is around 80% of the maximum speed for the spindle.

Because Haas machines are a bit limited in power it is best to try and stick with smaller diameter cutters as much as possible otherwise you can readily bog the spindle down, and play a little to find the sweet spot.

Another approach is use helix and/or variflute cutters because these do have lower power requirements for good removal rates, and don't expect to take heavy cuts with a large diameter facemill.

[Cory]

Originally Posted by anemachinebc On our bigger horizontals i run a 1/2 rougher at 10,000RPM .3 down, 60% engagement, at 150ipm, this works really good.

I can make this cut, or close to it, at about 100% spindle load on a VF-1 with the 10k spindle and gearbox.

[mls]

Cory I thought you can only get the gearbox with the 7500 rpm spindle. I have only bought used machines so I never looked into this but I would really like the 10k and the tourqe with the gear box I do a lot of titanium work with 3/4 in tools.
Thanks Mike

[Cory]

Originally Posted by mls Cory I thought you can only get the gearbox with the 7500 rpm spindle. I have only bought used machines so I never looked into this but I would really like the 10k and the tourqe with the gear box I do a lot of titanium work with 3/4 in tools. Thanks Mike

When we got our machine I specified that I wanted the non-gearbox 10k spindle, as I didn't want to spend an additional $4400.

The quote sat there for awhile while our financial people did their thing, and eventually when we were ready to buy our sales rep told me that the non-gearbox 10k spindle was replaced with the gearbox+10k spindle. This was late 2006/early 2007. This is what we ended up getting.

[peter.blais]

I'm using a .750" ski carb .333" deep- 120 ipm, 9000 rpm. With 75% stepover I see consistant 65-75% load. It spikes to ~98% when it hits a funky corner or whatever in the G code and goes full width for a second.

The only reason i'm using a 3/4 is because i need to pocket down 3" and the long 1/2's you can't push very hard. If I go much more then this even with the 3/4 the finish goes to hell and the noise goes way up.

If you could avoid the tough corners and stuff in the toolpath it could be run faster in general.

The 1/2's i'm using ski carb again, 100 ipm / 10k rpm up to .5" DOC and the spindle load % is lower. I'm thinking about trying an SGS S carb 3 flute as I'm out of rpm. I think it would go 140-150 ipm easily.

This is with a 5 week old VF2 w/ 10k rpm spindle and NO gearbox.

If you think these are underpowered go try running the 2hp bridgeport boss cnc I was running before we bought this. That 3/4 ski carb would stop it dead at any DOC unless on the low speed gear. It's all relative.

[Geof]

Originally Posted by peter.blais ......The 1/2's i'm using ski carb again, 100 ipm / 10k rpm up to .5" DOC and the spindle load % is lower. I'm thinking about trying an SGS S carb 3 flute as I'm out of rpm. I think it would go 140-150 ipm easily.....

My 2hp Bridgeport (clone) days are so far back I forget them.

Post what happens with the 3 flute. Based on my experience I think you have a good chance of loading the flutes and leaving a stub of cutter in the collet with the other end buried in aluminum. Mine was not a SGS when I tried a similar cut and got that result.

[Edster]

The sgs s carb 3 flute endmills work great in aluminum. I've had my okuma's load meter at 180% slotting .75 deep full width 10k rpm and 150 ipm with a .5" 3 flute endmill. This was Tib2 coated.

SGS has a nice demo at the IMTS show where there using a haas vf2ss to make some serious aluminum chips. Here is a link to a vid of the same demo I saw at IMTS http://www.sgstool.com/videos/video/video-actscarb.html

[peter.blais]

Haha, tonight I tried increasing the DOC to .5" with the .750 ski carb on the vf-2 / 20hp. 120 ipm / 8k rpm / .495 doc... With the axial width up to about .6, it was 113% or so on the spindle.

It pulled the part out of the vise and broke the corners off the endmill before I hit stop. DOH.

I'm ordering the S-Carb's now, we'll see. I used to always use 3 flute on my bridgeport because it went a lot further with the 4200 rpm spindle, never had problems with the flutes loading up, but I was doing like .120" DOC on that.

That SGS video is what made me think to try the S carb, I can't really see anything the Ski-Carb does that the S carb doesn't, and they are way cheaper?

[Geof]

Originally Posted by peter.blais ....It pulled the part out of the vise and broke the corners off the endmill before I hit stop. DOH. ....

Yes all that torque from the spindle is going somewhere and some of it is pulling the part upwards.

[peter.blais]

Right- the Ski carb is a high helix EM too so it's pulling up even harder.

This part was a little funky for my fixture (longer then normal, hanging off the end a bit), I cut the stock a little longer then I should have so the endmill went full slotting right when it ripped it out, and went up on the DOC.

three wrongs make a broken endmill lol.


Anybody compared say- ski carb or s carb versus OSG blizzard or other? Seems to me SGS is charging a pretty healthy premium for those ski carbs.