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Hi guys
I have a 2.2kw water cooled spindle and my vfd is the askpower 131. I attach the manual of my vfd.
I have been dropping it as low as 100hz which means 6000rpm. I would like to know if I can drop it lower without hurting the spindle. Say 50hz or even lower if possible?
Anyone has any info?
Hi,
yes you can drop it lower but you won't get any increase in torque.
Many spindles are air cooled and because the fan the fan slows as the spindle running such spindles at low speed is to risk a bad overheat situation.
Your spindle being water cooled is less prone to overheat, but if you notice it getting hot stop immediately.
A 2.2kW spindle has a rated torque of:
T= (24000 / 60)*2*PI /2200
=1.14Nm
So don't expect to drive a 10mm tool in steel, in fact without taking light cuts a 6mm tool will stall a 1.14Nm spindle.
Craig
Only if the Spindle you have has a 3000 RPM rating which some do, it won't have any useful torque below 6,000 RPM and most don't go below 7,200=120Hz as they mostly cut at this speed, at 6,000 RPM they barely make it and have a high possibility of stalling, once you stall your spindle damage is quite possibleQuote:
Originally Posted by jimskeet
I want to drive 3mm tool to take light cuts on stainless. Like 0.3mm stepdown passes.
I have run it at 6000 rpm very often.
Hi,
you can run 24000 rpm asynchronuos spindles slowly but they are far from their optimum.
I was so dissapointed that my 24000 rpm spindle could not be run slowly and that it has so little torque to render it almost
useless in steel and stainless that I made a second spindle using a direct coupled 1.8kW AC servo, 3500rpm, 6.2Nm comt, 18Nm
overload. Works a treat in steel and stainless.
Craig
Thanks for the info
Hi guys.
I am bringing back the topic.
Is it safe to run 6 and 8 mm drills at 3000rpm or lower to drill wood with the 2.2kw chinese watercooled spindle? The drilling operation I need is one 8mm and one 6mm holes that are 35mm deep. I do them at 6000rpm now but I would like to do them with lower rpm if possible. Any thoughts?
Running them lower than the recommended limit can result in a burn out of VFD and/or motor.
The inductive reactance of the motor is so low at the lower frequencies, it has to be kept in the higher range otherwise the current/heat is destructive.
Al.
Thanks for the answer. The operation lasts a few seconds. You think it is enough to create a problem?
Depends if you want to roll the dice! :(
O/L can happen in milli -seconds!
Got it.
Thanks again
There are some of these spindle that can run at 3000RPM but they have a higher torque than the standard and there amp rating of 10.5a is higher for the 2.2Kw spindle, they have a longer body and rotorQuote:
Originally Posted by jimskeet
Just remember a drill requires more torque than milling so if you go to low and stall your motor then you will damage it and the drive, it may take it a few times before total failure
Get quality drills and they will run ok with coolant at the 6000 RPM most likely your minimum speed below 6000RPM there is no useful torque with these motors and even at 6000 RPM most find 7200 RPM is around what most find as an ok running speed as far as torque goes