[gianluca70]

hello everyone,
can someone who has the "chinese" 2.2 kW + VFD answer a simple question?
I am going to buy one because i want to be able to make some machining at about 2000-3000 rpm, or even much less (40-60 rpm) if I want to use a fly cutter, but looking around in the various forums it seems anyone use them at very high speeds, like 18000 or 24000 rpm... now the question is: I understand the air cooled version will overheat at low speeds, but if I get the water cooled one, what is preventing me to run it at 2000 rpm?? not enough power? has anyone actually machined something at this low rpm with those spindles?

Thank you for your help, I looked everywhere for this and did not found any useful info

[dharmic]

Advice from the supplier of mine was to never run it below 6000rpm at load.

I fly it at about 1000 for edge finding, it will run at 3000-4000 ok when I'm milling mild steel with it but it's really light cuts or the thing just stalls. And I have no idea what running it slow is doing to the bearings, the coils or the VFD driving it. So I tend to avoid it where possible.

[gianluca70]

thank you Dharmic

[dharmic]

No dramas.

Horses for courses and it sounds like your course is a much more traditional application and arrangement that calls for the bigger, heavier, lower RPM and higher torque motors.

In fact, if you're going for both 2000-3000rpm and down to 60, I reckon you're going to be looking for something chunky with a multi-range gearbox.

[Christian Knüll]

Hi,

the spindles have very little torque below 6000rpm - at least with the usual VFDs (vector control VFDs can increase torque significantly - but still can't do magic).
Its just a simple 2 pole induction motor with rather light bearings - it is not designed to run slow.

For low rpm / high torque applications more poles and stronger bearings are required.

Christian

[mactec54]

hello everyone,
can someone who has the "chinese" 2.2 kW + VFD answer a simple question?
I am going to buy one because i want to be able to make some machining at about 2000-3000 rpm, or even much less (40-60 rpm) if I want to use a fly cutter, but looking around in the various forums it seems anyone use them at very high speeds, like 18000 or 24000 rpm... now the question is: I understand the air cooled version will overheat at low speeds, but if I get the water cooled one, what is preventing me to run it at 2000 rpm?? not enough power? has anyone actually machined something at this low rpm with those spindles?

Thank you for your help, I looked everywhere for this and did not found any useful info

You did not find any info because they can not safely run that slow, lots have tried but most end in failure

The spindle is not designed to run this slow, to get it to run slow you would have to have a low minimum Hz setting, and for these spindles 100Hz is the minimum you can safely use, anything else and the spindle will overheat and eventually destroy itself

[Al_The_Man]

See post #5.
http://www.cnczone.com/forums/spindl...ting-help.html
Al.

[gianluca70]

I was thinking the minimum of 100 Hz applies only to the air cooled one... thank you anyway to all for you, useful information. I will probably get it it anyway so at least I can hopefully solve the problem of the noise that I am getting from my current spindle

[mactec54]

I was thinking the minimum of 100 Hz applies only to the air cooled one... thank you anyway to all for you, useful information. I will probably get it it anyway so at least I can hopefully solve the problem of the noise that I am getting from my current spindle

The air cooled spindles is around double as the minimum setting so if it is a 400Hz spindle it would have a minimum of 200Hz

[talootfouzan]

hello everyone,
can someone who has the "chinese" 2.2 kW + VFD answer a simple question?
I am going to buy one because i want to be able to make some machining at about 2000-3000 rpm, or even much less (40-60 rpm) if I want to use a fly cutter, but looking around in the various forums it seems anyone use them at very high speeds, like 18000 or 24000 rpm... now the question is: I understand the air cooled version will overheat at low speeds, but if I get the water cooled one, what is preventing me to run it at 2000 rpm?? not enough power? has anyone actually machined something at this low rpm with those spindles?

Thank you for your help, I looked everywhere for this and did not found any useful info

2000 to 3000 yes it will be usable even at 1000 rpm with correct vfd/motor size and setup, but for 40-60, it wont even spin, go for stepper motor as spindle