Build Thread- VF4 ss RPM question

[nfs7713]

How long can I run a 3/16 R corner rounding end mill at 11000 rpmscutting radius in alum. before letting the spindle
cool off?

[HuFlungDung]

6 seconds

Can you aim a little bit of coolant at it? Then you could run longer

[nfs7713]

Yeah, we are running coolant.

[Donkey Hotey]

If I'm not mistaken, the coolant runs through the head casting. That actively cools the whole thing. You should be able to run continuously. What are you asking or why are you worried?

[nfs7713]

just curious, thanks for the reply

[extanker59]

For the last 3 days, I've been running a 1/32 endmill at 11000 rpm. No noticable problems. I'll yell loud here if I do.
I am usually up to 11000 fairly often as most of our tools are small.
It's a vf-2ss. Can go up to 12000 but I'm nervous about spindle life so I try not to go there.
I am not aware of any cooling off period but I do run the spindle warm up, first thing in the morning, if I'm going to 9000 or higher right away. I run it every Monday too, of course.

[Geof]

On some jobs we have a VF2 running at 11,000 rpm at a spindle load of up to 120% for about fifteen minutes of every hour and the rest of the hour it is running at 10,000 rpm. Most of our machines are running at 10,000 rpm 80% of the time and some have several thousand spindle hours so I don't think you need to worry.

The Warm Up cycle is essential though after a weekend. Run the spindle at 10,000 rpm after it has been stationary for two or three days and it can be too hot to touch within about ten minutes.

[fuzzyracing1967]

I must be real cautious,I insist a warm up program be run if the part program goes over 4000 rpm,and will stick with that since we never had any problems,knock on wood.
The other thing we allways do is run at 50% in the rapid for the first 10 minutes or so in the morning,i figure it can't hurt.
Hell anymore I get up and have to move at 25% first thing in the morning,why ask a whole lot more from the machine

[JohnJW]

This a great support group. I thought I was the only one afraid to push the spindle speed above 10K. For spindle warm up I also set rapid to 5% and added some G00 moves in between the ramping spindle rpm to get the table to move through it entire range of travel while the spindle is warming up.

I push it up to ~11500rpm for small diameter tools and the spindle load is near zero during cutting. However I'll begin pushing the rpm up for larger diameter tool . . . . from what I've ready, it's perfectly safe. . but sometime it's like watching that rapid down to Z.1 it still cause my heart to skip a beat.

[Geof]

Originally Posted by JohnJW ...... However I'll begin pushing the rpm up for larger diameter tool . . . . from what I've ready, it's perfectly safe. . but sometime it's like watching that rapid down to Z.1 it still cause my heart to skip a beat.

A 3/4" high helix two flute running full width, 0.40" deep at 14,000 rpm and 140 ipm with a spindle load of around 180% tends to make your heart skip a beat.

It also is deafening which is why we don't run those speeds under normal conditions, I was seeing just what the machine could do.

[samhyto]

It is really amazing how fast we can push our machines. We have one setup we hog out with a 3" shell mill on a 4" tombstone on an hrt-210....and when the tool starts making chips, its a violent chip storm inside the enclosure, and violent is still and understatement. My brother does a part in 3" delrin and drills it using a G00 with the rapids set at 50%, granted, its an insertable spade drill with thru the tool coolant and plastic, but it is one hell of a sight to see.

Back to your original concern...are your toolholders balanced? If you are spinning above 10K, it is highly recommended to use balanced toolholders appropriate to the rpm. I would also open all the coolant lines at the spindle. Even of they are pointed to to rear of the cabinet, the coolant cavity in the spinlde head completely surrounds the spindle and will assist in disapating the heat generated in the spindle bearings.

Spindle warmups are the norm on Monday morning.

Sam