Analytical derivation of thread profile in internal thread milling process

Abstract

Thread milling is a new machining process as compared to thread tapping. As a thread making process in use for a long time, thread tapping did not have any alternative processes except the thread turning for limited cases until computer numerical control (CNC) technology had enabled the three axes synchronized motion. Therefore, investigations about the thread milling process are less as compared to other machining processes. In this work, the thread profile in the internal thread milling process was derived analytically. Experimental work was also performed to verify the performance of the analytical model. It was revealed that the thread profile produced by the cutting edge of the tool is not a straight line but a curve, and the average slope through the thread profile is less than the slope of the cutting edge of the tool. Besides, the effective thread profile enlarges along the vertical axis and constricts laterally as the ratio of thread mill diameter to thread diameter increases.