VFD and Motor RPM

Greetings,

I have a CNC mill with a VFD controlled spindle. The factory manual, full of errors, states the RPM range of the system is 500-4000 RPM.

The machine will accept a Spindle command of less than 500 RPM and the motor turns.

My question is this. Will running the motor slowly, under 500 RPM, cause damage?

With my machining needs, a slow spindle speed would be advantageous. However, not at the expense of replacing a damaged unit.

Cheers,

Dave

Most likelly below 500 rpm you will not have:

Torque
Enough motor cooling

The manufacturer is protecting himself with those instructions. If you post some pictures of the machine or more details probably you will get better quality answers than mine.

Greetings emcPT,

Thanks for the reply.

More clues. As the motor turns slower more heat is generated?

My cutters are usually under 3/8" so torque may not be an issue.

Motor VFD is a SunFar C300-2S2202, Model 2

Motor is a Anhui Wannan Electric YVF2-901-4 220V 1.5Kw

Cheers,

Dave

Yes, if your motor turn slower and probably since the only refrigeration is from the attached shaft vent (if the motor is stopped, no air is flowing) motor will heat up. Also at lower speeds you will get higher amperages, so the tow together will result in more heat. One solution would be:

Add forced vent (will not get you a better torque)
Make a reduction if you can (you will be able to work at slower rpm with good torque) but unable to reach so much higher speeds