Milling machines with “through-the-main-spindle” coolant pressure have been gaining popularity. This through-coolant feature is used mostly for drilling applications using drills that include through-holes. SFI’s Toodle Blue™ models use through-coolant pressure to drive the Toodle Blue™ turbine.

Toodle Blue models include special jets which convert pressure into linear speed. Higher pressure values deliver higher linear emulsion flow speed. The linear fluid speed (tangential speed) has a direct influence upon Toodle Blue turbine rotation speed. Its equation is expressed as:  v=ωr (tangential speed is the product of angular speed and radius).

The milling machine emulsion pump has two main parameters: Pressure and Flow Rate.

Pressure multiplied by Flow Rate equals Power: POWER [w] = Pressure [Pa] x Flow Rate [m³/s]

The pump’s maximum pressure is a function of the pump’s “conceptual constriction”. In other words, in order to deliver high-pressure the pump must be designed to withstand high pressure. The pump’s flow rate is a function of the pump size.

A given pump may have relative high-pressure limitations and low flow-rate abilities.

Using a low-power pump (low-flow rate) in combination with Toodle Blue models will deliver a reduction in pressure and therefore a reduction in Toodle rotation speeds.

The relationship between pressure and flow rate can be found at:[21eb3171ffe7a6994b6]/0

When using emulsion and with reference to water viscosity, one can calculate pump-power.

The viscosity of emulsion (95% water) is very similar to that of water and therefore is not greatly affected by temperature changes.

When purchasing a new milling machine, it is best to confirm that its flow-rate and power of the pressure-pump match the Toodle Blue’s requirements:


Different pumps have different mechanical and electrical efficiencies. Therefore, the electric motor connected to the pump should deliver adequate power for running the Toodle Blue™ models. The normal efficiency of electrical motors is between 80% to 85%.