Abstract: On line and real time monitoring of machining of micro holes was investigated.The monitoring was carried out measuring drilling torque.Under the present work,limit values of drilling torques are weibull distribution of three parameters.Reliability function of the torques is derived from the function with weibull distribution of three parameters.Critical value of drilling torques for the monitoring is obtained from the reliability function.From the critical value,process of machining of micro holes is monitored,preventing from breaking of micro drills.So that,the use of micro drills can be improved from the present work.

Key words: micro drill, drilling torque, on-line monitoring