International Journal of Materials, Mechanics and Manufacturing, Vol. 1, No. 1, February 2013 76 DOI: 10.7763/IJMMM.2013.V1.16 Abstract—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. Index Terms—Chip, cutting speed, feed rate, and saw tooth. I. INTRODUCTION The intricacy connected with the hard turning process from a material deformation and chip formation standpoint is yet meagerly documented. Particularly, comprehending chip formation is crucial considering that it influences the selection of the material grade of the cutting tool along with workpiece quality related factors like residual stresses as well as white layer formation relating to the machined work surface. Significant consideration ought to be presented to chip control because of its growing benefits in underlying effective machinability. A useful hypothesis reported in [1] on chip formation in turning being a result from crack initiation was an impulse to us for further investigation. Further clarification in [2] emphasized the influences of cutting speed to the formation of chips. The present study revealed the effect of feedrate as another factor of consideration in chip formation while turning hardened materials. Recent study [3] presented the relationship between the chip geometry, the cutting conditions and varying micrographs at different metallurgical states. This study is however, aimed at obtaining the chips resulting from varying cutting conditions that has been carried out during the machining test and evaluating same by way of examining the mechanism involved during the formation of the chips. Manuscript received November 10, 2012; revised January 5, 2013. Adam Umar Alkali and Hasan Fawad Junejo are with the Department of Mechanical Engineering at the Universiti Technologi PETRONAS, Malaysia (email: adamu_g01876@petronas.edu.my). Noordin Mohd. Yusof is with the Department of Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia (UTM), Skudai, Johor. Mohamed Handawi Sa’ad Elmunafi is with the Department of Mechanical Engineering at the University Technology Malaysia. II. TOOL AND WORKPIECE MATERIAL A. Workpiece Material ASSAB DF-3 (cylindrical bar) through hardened tool steel was used as the workpiece material. DF-3 general purpose oil hardened tool steel is a versatile manganese-chromium -tungsten steel suitable for a wide variety of cold-work applications. DF3 tool steel influenced a choice for this study because of its good machinability, good dimensional stability in hardened state, good combination of high surface hardness and toughness after hardening and tempering. B. Cutting Tool Material A rhomboid shaped coated wiper ceramic tool from Kennametal was used for the machining test. The inserts was ANSI coded CNGA 120412EFW, and has a tool nose radius (rε) of 1.2 mm. The ceramic tool was mounted on left corner tool holder that was geometrically coded Kennametal MCLNL 16161412. The cutting tool has the following geometry; Side rake angle  = -5 Back rake angle α = -5 Side cutting edge (SCEA) = -5 Nose radius r = 1.2 mm III. EXPERIMENTAL SETUP The workpiece was machined on the faces to obtain a proper shaped facial area. The workpiece was center drilled at both ends to enable support between centers both in order to minimize vibration as well as impact of forces resulting from the material removal. Cutting tool was mounted and securely held in position and aligned with the workpiece at both X and Z coordinates being reference for the machine set up. A chamfer was made at the end of the workpiece to facilitate tool entry. The chip specimens were prepared for microscopic examination. Collected chips were mounted, hand grinded with little caution using sand paper of various grades, typical are 230, 320, 500, 1000 and 1200 in order. The specimens were manually polished with aid of alumina paste and were later etched. Etching is performed with controlled preferential attack on the metal surface in order to reveal available microstructural details. Villella’s reagent was used with the composition of 1g Picric acid, 5ml HCL and 100ml of ethanol. The typical exercise was to dip the prepared chips into the etchant for between 5 to 10 seconds, followed by washing with flowing water, then drying using hot air. The structure obtained enables us to evaluate the flow of the chip grain structures and also to determine the shape of the chips under microscopic view. Adam Umar Alkali, Noordin Mohd Yusof, Mohamed Handawi Sa’ad Elmunafi, and Hasan Fawad Influence of Cutting Conditions on Chip Formation When Turning ASSAB DF-3 Hardened Tool Steel