PMI's design of hollow cooling system is especially good for high speed Ballscrews. It shall well dissipate heat generated by friction between balls and grooves during Ballscrew running, and then to minimize thermal deformation as to ensure positioning accuracy.


The hollow cooling system is designed by PMI It uses a coolant pipe through the hollow hole of Ballscrew. The hollow hole is through all of the Ballscrew, and one end is clogged with the oil seal by PMI patent. The coolant is pumped into coolant pipe and fl ow to the end of coolant pipe. Coolant then fl ow reversely along the hollow hole back into the coolant collector. It can cool down the Ballscrew. The coolant is then sucked back to the cooling unit to drop coolant temperature and pumped again to the coolant pipe to complete circulation.

Thermal control experiment

Test condition

Screw nominal O.D. : Ø 40 mm
Lead:10 mm
Rotation speed:1000 mm
Speed:10 m/min
Load:400 kgf
Slideways:Hardened ways

The results of experiment
As per the results by experiment, PMI 's design of hollow cooling system proves an effective way for controlling the thermal expansion on the Ballscrew. Hence it is a very helpful design to high precision machine tools.