Modeling of interferences during thread milling operation

Thread milling is becoming more and more employed as a technique for producing thread due to its advantages for industrial manufacturing sectors, such as the aeronautics, aerospace, and energy industries. The thread milling operation is atypical and several aspects have to be taken into account to perform it in good conditions. As for milling or grinding worms, grooves, thread, or other sculptured surfaces, in thread milling, there exists a geometrical interference between the tool and the nominal surface which would be obtained. Thread mills have quite complex geometry and their profile has an effect on the machined thread. The present study details geometrical aspects of the thread milling process. This article deals with the link between thread mill geometry and nominal thread profile. An approach is proposed to analyze the thread profile generated by the thread mill envelope. It is deduced that thread milling produces interferences, i.e., the machined thread profile is affected by an overcut. A method is proposed to correct this geometrical error in order to produce accurate thread.