Spindle motors are designed to rotate at high speeds, so the parts of them must be highly durable and manufactured within tight tolerances. This is particularly important for the bearings, which are designed for high speeds and must not heat up. High-speed bearings also tend to be more expensive, because they are made with special materials and lubricants.
CNC machines have three axes: the x-axis, y-axis, and z-axis. The z-axis introduces a third dimension. This is the key to the CNC process. In addition to the X-axis, CNC machines operate along a z-axis, and the spindle motor moves the spindle up and down the z-axis. The spindle motor is often used in CNC tools and is highly efficient. It can handle multiple jobs and offers high-precision movements.