High-Pressure

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. ...

High pressure coolant systems in deep hole drilling machines operate at 1000-3000 psi. The seals and O-rings that contain this pressure need to be selected carefully. A failed seal causes pressure loss, downtime, and can ruin a workpiece mid-cycle. I have learned these lessons the hard way over eight years of maintaining high-pressure coolant systems across a dozen machines. Material Selection by Operating Conditions The seal material must withstand the coolant chemistry, temperature, and pressure simultaneously. I have tested five materials extensively and settled on the following guidelines: ...

The Real Danger of High Pressure Coolant High pressure coolant systems in deep hole drilling run at 1000-2000 psi. At those pressures, a pinhole leak creates a jet that cuts through skin like a scalpel. The entry wound looks small and harmless. The coolant carries bacteria and metal fines deep into the tissue, and the infection that follows is what causes permanent damage. I have seen a maintenance technician get a coolant injection injury from a pinhole leak in a hose that looked perfectly sound. The leak was invisible at idle but opened up under full pressure. He needed two surgeries to clean out the infection. The hose had been in service for three years. ...