A study on environment-friendly machining of titanium alloy via composite electrostatic spraying

Compared with minimum quantity lubrication, electrostatic spraying can greatly improve machining and environmental performances. However, the cooling and lubricating performance of electrostatic spraying needs to be further improved. In this paper, the composite electrostatic spray cutting approach is proposed, and the environment-friendly machining of titanium alloy by using this approach is investigated. An atomization test device for composite electrostatic spray cutting and a composite electrostatic spray milling system are developed. The atomization tests for composite electrostatic spray cutting are performed to study its atomization morphology and to determine the atomization parameters that guarantee a stable composite electrostatic spraying. The atomization current is measured by using a picoammeter under stable composite electrostatic spraying conditions, and the charging performance and atomizing stability of composite electrostatic spraying are evaluated. Milling experiments of titanium alloy and ambient oil mist concentration tests are also carried out under electrostatic and composite electrostatic spraying conditions. The effects of composite electrostatic spraying on milling force, tool wear, chip morphology, and oil mist concentration are analyzed. Results show that compared with electrostatic spraying, composite electrostatic spraying can effectively reduce tool wear and oil mist concentration. Under composite electrostatic spraying condition, an increase in the flow rates of internal and external fluids can further reduce tool wear. An increase in the flow rate of internal fluid does not affect ambient oil mist concentration. But an increase in the flow rate of external fluid significantly increases ambient oil mist concentration.