Influence of Cutting Conditions on Chip Formation When Turning ASSAB DF-3 Hardened Tool Steel

Machining investigations were made on ASSAB DF-3 oil hardened tool steel HRC 45 using wiper coated ceramic tool. Both cutting speed and feed rates were purposely and continually changed to enable investigations performed at various cutting combination. Both cutting speed and feedrate were found to influence the formation of saw tooth shape on the chip from a non-saw tooth shape. The chip forms collected were observed using digital camera and optical microscope and were studied in terms of their form, thickness and micro hardness. The saw- tooth chip obtained in this study was a result of some interrelated mechanisms such as localized shear, adiabatic shear and also as a catastrophic shear in the form of extensive cracks. A relationship was established between the chip geometry and the cutting conditions.