Part i - spindle facts

Likewise, a spindle cooling jacket indirectly removes heat created by the moving rotor and
internal winding that has transferred to the stator. The drawback is, of course, that the cooling
media cannot contact the inside of the motor, particularly the ends of the windings where heat is
greatest. In addition, the cooling water has to be pumped through a separate heat exchanger,
adding to the cost.
Depending upon the spindle design, estimated cooling system capacity can vary. The next charts
show informative relations between heat dissipation and cooling water flow quantity:
SPINDLE MOTOR COOLING RECOMMENDATIONS
Heat Removal Requirements Flow Inlet Liquid Temp. to
kW
l/min
Spindle (°C)
5.0 12.0
5.5 13.5
7.0 18.0
4.0 10.0
26 °C
6.5 16.5
7.5 19.0
12.5 32.0
A spindle can be furnished with internal passages for thermal bearing control:
THERMAL BEARING CONTROL RECOMENDATIONS
Heat Removal Requirements Flow Inlet Liquid Temp. to
kW
l/min
Spindle (°C)
0.50
0.75
2.0 30
Another possible system involves using air as the cooling medium.
This system blows cool outside air simultaneously around the
stator and through the motor. It allows for a very effective method
of cooling both the inside and outside of the integral spindle motor.
The effectiveness of this system allows the motor to run cooler,
thereby generating more power. This system effectively keeps the
heat away from the machine resulting in reduced dimensional
thermal effects.
The cold outside air is typically sucked through a filter from the
rear of the machine through the motor. The exhaust typically goes
to the top of the machine, blowing the warm air away from it.
Figure 26.
Air cooling
- 26 -