Abstract
With the advent of numerically controlled machines the problem of facing and turning with the same tool was solved by the use of negative side cutting edge angles (SCEA), also known as lead or approach angles. The development of 80° diamond shaped inserts have made them more versatile not only for use with −5° but also with 0° and 15° SCEA's. Despite their success, their performances have not been analyzed and reported in textbooks or in journals. Three tools with SCEA's of −5°, 0°, and +15° were used to machine low carbon steel (1018) at speeds of 450, 560, and 710 sfm at a depth of cut of 0.1 and a feed of 0.01 ipr. Cutting forces were measured and friction and shear plane angles determined. Chips and chip roots were analyzed for secondary shear zone formation. Chips were sorted into nine distinct-color categories using digital color imaging techniques. Surface roughness and roundness, and brightness measurements were made. Results indicate that the tool with −5° SCEA performed better than the other two and the reasons for this age highlighted in this paper.