Mollart Engineering has developed a low-cost, spray mist coolant system that can be utilised on deep hole drilling applications and can be retrofitted to any machine tool.
It is fed from a standard compressed air line at pressures up to 10 bar and is useable on holes between 5 and 25 mm diameter by up to 2,000 mm deep.
The spray mist system is highly efficient for deep hole drilling, with the air passing through the system absorbing precisely timed pulsed jets of vegetable-based cutting oil from an integrated reservoir. To illustrate the efficiency of the system, if the gundrill is removed from the component it will be immediately cool to the touch.
The oil is used to lubricate the tip of the drill and its guide/support pads, which prevents any seizure occurring in the hole, while the air purge effectively cools the cutting edges of the tool and its guide pads. Meanwhile, the pressure of the air behind the chipped swarf forces it back along the vee groove (flute) between the outside diameter of the gundrill tube and the drilled hole to clear the cutting zone.