Spindle + VFD Questions

Hi all,

So I'll try and make this short and concise. I'm going around in circles researching spindles and VFD'S, and could use some help.

I'm looking at a 4kw air cooled spindle, JGF-4.0KW.
I have found them with and without a VFD.

1. Should a vfd be rated for twice the motor current rating?

2. What is the calculation or low end speed I should expect to be able to get from the 4kw spindle?

(The top rated speed is 18,000rpm, would I be hoping for something impossible if I needed my low end speed between 5-6,000 rpm?)

Thank you for your time,

Travis

If you're feeding it single-phase current, then 2x would probably be a good idea. If you've got native 3-phase, it's overkill. Figure the thing will work at about half the top speed, but not below that. The torque falls off and the fan's less effective, which can kill an air-cooled spindle. On yours, figure 10k rpm as a safe low-end speed.

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Originally Posted by awerby

If you're feeding it single-phase current, then 2x would probably be a good idea. If you've got native 3-phase, it's overkill. Figure the thing will work at about half the top speed, but not below that. The torque falls off and the fan's less effective, which can kill an air-cooled spindle. On yours, figure 10k rpm as a safe low-end speed.

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Thank you for response, and yes I'm running on single phase, 220v. So I should expect to run a vfd rated at twice the amps for single phase to get the full range of rpm from the spindle. As far as the 10,000 rpm lower end limit, does that change if you use a water cooled spindle? Or is that a torque fall off below that?

Also one last question, other than buying a mafell or amb, does anyone know of a spindle that will range between 5,000-18,000 rpm?

Thank you again for your time,

Travis

A 4kw spindle rated at 10 amps is really a 2.2Kw spindle.

That's probably why it's $299.

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Originally Posted by ger21

A 4kw spindle rated at 10 amps is really a 2.2Kw spindle.

That's probably why it's $299.

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Unless they have the voltage incorrect that would be a 380v 4Kw 10A

Quote:

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Originally Posted by Blendwood

Thank you for response, and yes I'm running on single phase, 220v. So I should expect to run a vfd rated at twice the amps for single phase to get the full range of rpm from the spindle. As far as the 10,000 rpm lower end limit, does that change if you use a water cooled spindle? Or is that a torque fall off below that?

Also one last question, other than buying a mafell or amb, does anyone know of a spindle that will range between 5,000-18,000 rpm?

Thank you again for your time,

Travis

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Water cooled spindle are normally 6,000 RPM to 24,000RPM some will go as low as 3,000 RPM depending on manufacture

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Originally Posted by mactec54

Water cooled spindle are normally 6,000 RPM to 24,000RPM some will go as low as 3,000 RPM depending on manufacture

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Thanks Mac, I'll have to do a bit more looking