I plan to replace the spindle motor for my CNC engraving machine, but I don't know whether to choose a water-cooled spindle motor or an air-cooled spindle motor. I have two options:
1. https://www.oyostepper.de/goods-804...-400Hz-ER11-Spannzange-für-CNC-Gravieren.html
2. https://www.oyostepper.de/goods-808...Umin-400Hz-ER11-Spannzange-für-CNC-Motor.html
Which performance is better?

 

Welcome to AAC.

Water-cooling is generally more efficient which results in a higher duty cycle capability (i.e. longer machining runs) and might explain the higher input current on the air-cooled spindle (5A v 4A, i.e, higher losses for same output?). Otherwise weight, size, speeds are identical so no obvious difference in performance otherwise.

Water-cooling requires extra equipment: pipes, water reservoir, pump, radiator (possibly) which is added expense and complexity (and mess when it invariably springs a leak!).

I'm answering as a home-CNC'er, all my stuff is air-cooled through necessity but given the choice and opportunity I'd probably opt for water-cooling.

You might get a more focussed answer on a more appropriate form such as CNCZone or HomeMachinist

 

UNless you are running production with the engraving machine so that it runs almost constantly, and at a load level above 50% of its capability, AIR COOLED is the way to go. Post #2 lists valid concerns, but does not mention the corrosion problem, which includes unseen rust in different sections of the cooling loop. If this is a hobby application and you use air cooling, get a normally open thermostat set to about 20 degrees below the motor max rated temperature, to attach to the motor to light a warning when the motor is getting hot. An external fan blowing on the motor would be the way to go at that point, or a less aggressive machining rate.

 

What Bill and Irving are saying is that you want (or need) water cooling when the load is heavy. But if it's a light load then air cooling is right. Why engineer a machine that can withstand 5,000˚F if it's never going to see anything above 120˚F?

 

On a side note, water cooled are rarely seen on commercial CNC machines, especially an engraving table where the load is relatively steady and not high.

 

Max is speaking from experience, and my experience is that water cooling was only used in oil to water heat exchangers in some high powered LARGE hydraulic power system packages, and in some specialized refrigeration systems for very cold thermal chambers.