To reduce drilling temperatures and improve the machining quality of CFRP/Ti6Al4V laminates

this study proposed a cryogenic minimum quantity lubrication (CMQL) technique

utilizing the high solubility of lubricant in supercritical carbon dioxide (ScCO

2

). Tests were conducted on the droplet atomization performance and output temperature of the CMQL system

followed by low-frequency vibration drilling experiments under CMQL conditions for CFRP/Ti6Al4V laminates. The influence of CO

2

pressure on laminate drilling was analyzed. The results demonstrate that increasing CO

2

pressure enhances the atomization and cooling capability of the CMQL system. When the pressure increases to 8 MPa

CO

2

presents as supercritical state

and the output temperature drops to below –80 ℃. As the system pressure rises from 5 MPa to 9 MPa

the drilling temperatures of CFRP and Ti6Al4V layers decrease by 15.91% and 50.78%

axial forces increase by 65.22% and 20.26%

and torques decrease by 23.33% and 16.77%

respectively. Moreover

the burr height at the Ti6Al4V layer exit decreases by 42.04%

the delamination factor at the CFRP layer exit is reduced by 5.41% and a low roughness of borehole wall of CFRP/Ti6Al4V laminates is achieved at pressures of 7 MPa

8 MPa and 9 MPa.