In order to reduce the axial force of the pneumatic drilling on the aircraft titanium alloy skin crack hole

the pneumatic drilling force test system was constructed

and the orthogonal test and the parameter optimization test of drilling force were carried out. Experimental results show that the effect of the axial force on the pneumatic drilling is in the order of velocity feed ratio（v/f），drill bit shape and lubrication conditions. When the S-type drill of W6Mo5Cr4V2Al is used to drill the 2mm thickness titanium alloy TC4 sheet

the motor cutting speed can be adjusted to 445-865 r/min

and the composite droplet jet lubrication (CMJ) is used. The lubrication parameter is set to atomization gas pressure of 0.4MPa

oil consumption of 80-100mL/h

water consumption of 200-400mL/h better.