Pump-Selection

The coolant pump is the heart of any deep hole drilling system, and I have seen more production downtime from pump failures than from spindle issues. The pump must deliver consistent pressure and flow at the tool tip, and the maintenance approach is completely different from the standard sump pump on a CNC lathe. Pump Selection Criteria The pressure and flow required depend on the drilling method, tool diameter, and depth. For gun drilling, the rule of thumb I use is 800 to 1,200 psi (55 to 83 bar) for diameters under 20 mm, and 400 to 800 psi (28 to 55 bar) for diameters above 20 mm. BTA drilling typically runs at lower pressure, 200 to 500 psi (14 to 35 bar), but requires two to three times the flow rate. ...

The coolant pump is the heart of a deep hole drilling machine. The right pump delivers adequate pressure and flow for the drilling application. The wrong pump causes chip evacuation problems, poor surface finish, and tool breakage. I have specified pumps for eight deep hole drilling systems, and I have made both good and bad choices that taught me what matters. Pump Types by Drilling Method For gun drilling, a positive displacement pump is the right choice. It delivers consistent pressure regardless of flow demand. The two most common types are piston pumps and progressing cavity pumps. Piston pumps use reciprocating pistons to pressurize the coolant. They deliver pressure up to 3000 psi with good efficiency. Progressing cavity pumps use a rotating helical rotor inside a stator to move the coolant. They deliver pressure up to 2000 psi with less pulsation than piston pumps. ...