Spindles - Water-Cooled vs Air-Cooled

At CNC Online South Africa, we stock water-cooled and air-cooled spindle kits. In this article I will be discussing how to choose between a water or air-cooled spindle.

Click here to view our air-cooled spindle.

Click here to view our water-cooled spindle.

People are generally a bit lost when deciding between a water-cooled or air-cooled spindle. There are only a few things that need to be considered during this selection process.

Cooling in a water-cooled spindle is achieved by circulating water via an external pump into and out of an internal shell inside the spindle. Upon exiting the spindle, the water is pumped into a vat of water which is cooled by the surrounding air temperature.

An air-cooled spindle has a cooling turbine attached to the shaft of the spindle. When the spindle is spinning it causes the turbine to spin, drawing ambient air into and through the internals of the spindle. As the turbine is connected directly to the shaft of the spindle it is spinning at the same speed as the bit (8000 – 24000 rpm) which is pretty fast! The turbine speed drawing air rapidly into the spindle causes a high-pitched whining noise, which if you are running in your garage at home, might upset your neighbors.

If noise is an issue water-cooled is the way to go. Secondly, the heat transfer rate of water is approximately 24 times better than air. Therefore, a water-cooled spindle will run cooler which in turn will increase the bearing life of the spindle.

Not all is bad with an air-cooled spindle, there is no need for fiddly water pipes and a large vat of water on your shop floor which will likely be kicked over at some point (we are solving this problem by creating a closed loop cooling system with a radiator which will be available soon). A water cooled spindle is also slightly more expensive than an air-cooled unit.

So, to conclude, if noise is not an issue, go with an air-cooled spindle as its less of a hassle to set up, it’s cheaper and there is no vat of water on the floor. If noise is an issue, you will need a water-cooled spindle.

Happy CNCing!!