[Vulin]

New to the swiss side of the house. I see parts are generally very small, so high rpms. Im used to the mill side of the house. If I have a 14k spindle, Im going to use it. We currently have Citizen A20's. With modern tooling I could be running both main and sub at max rpm. Do you guys do the same or back off for machine longevity?

[ProProcess]

There is not enough information to give you a good answer, but I'll offer the following with respect to running a swiss machine main spindle at high RPM...
Machine longevity is only a part of the equation, though it is a pretty big part.
The other more pressing and immediate deciding factors are bar diameter and condition.
Twelve foot bars that are not very straight will make your life "flash before your eyes" as you run for either the EXIT or ESTOP!!
Small bars that are not well supported can also cause impending doom.

[john-100]

some Swiss machines ( as in machines made in Switzerland)
turning small diameter parts your not limited to 10 or 12 foot bars you can have 30 to 60 Kg coils !
Attachment 336438

[ProProcess]

some Swiss machines ( as in machines made in Switzerland)
turning small diameter parts your not limited to 10 or 12 foot bars you can have 30 to 60 Kg coils !
Attachment 336438

Though what you say is true, the OP stated the use of a Citizen A20 - which is a bar fed machine.

[john-100]

For more conventional machines making comparatively long parts with a short cycle time
magazines holding 20 or 30 10 foot bars saves on manpower feeding the machines

[MCImes]

I agree with Pro, the reason to limit RPMs below max is not bearing or machine life, but vibration caused by the bar and related issues.

Also, I recently moved form 6 years programming Swiss to programming conventional lathes. SFM and IPR calculations on 'larger' stock (read larger than .500" material) holds very true. You can copy the tool manufacturers recommendations for speed and feed and you will get generally good results.

When things go tiny, like say turning .030 diameter pins, although theoretically you should be able to run your spindle flat out at 8k or 10k rpm, I have had problems in the past with material re-welding to itself, chip wrapping, bad finishes, and other issues. Although i was following recommended machining parameters, they simply didnt translate to small diameters and many times I had to reduce RPM to eliminate the issue. This was after trying various insert geometries, grades, and feeds; all that helped was reducing the speed. (this was more of an issue in tougher materials like Grade 2 Ti, 316 SS, and MP35N)

So if you're cutting aluminum or brass, run it wide open, limited only by bar vibration. If you cut tougher materials, you may see that 'normal' speeds and feeds do not translate well down to micro parts. After a while you'll find each job's sweet spot.

[chunkymonkey]

MCImes is correct. Running small diameters at max rpm will make your day rough more often than not. I tend to max using G50 SXXXX when going at tiny diameters. You can make up the pennies elsewhere.