Prediction of Tool Wear Mechanisms in Face Milling AISI 1045 Steel Patricia Mun ˜ oz-Escalona, Nayarit Dı ´az, and Zulay Cassier (Submitted June 8, 2010; in revised form April 5, 2011) Cutting tools have an important role in the machining process, since they are related to workpiece surface quality and production costs. Due to the importance of selecting appropriate cutting parameters during the milling process, this research develops empirical expressions to predict the tool wear mechanisms that a cutting tool will suffer during the milling of AISI 1045. In addition, an expression to predict the critical cutting speed value where the diffusion mechanism starts to appear is developed. AISI 1045 was selected as the workpiece material due to its excellent machinability, good abrasion resistance, and mechanical strength. The Design of Experiments method namely Taguchi was applied to reduce the time and cost of experiments. The results showed that the cutting speed is the parameter with the most influence on tool flank wear which started to appear when using V = 500 m/min and the diffusion tool wear mechanism at V = 850 m/min. Keywords cutting speed, Taguchi, tool wear, wear mechanism 1. Introduction Tool wear is related to all the cutting tools involved in a machining process, and once a tool is past its wear limit it diminishes workpiece quality. The cutting tool is influenced by different tool wear mechanisms such as: abrasion, diffusion, oxidation, fatigue, and adhesion. These mechanisms degrade the cutting tool to a final stage where the tool reaches the end of its life. It is very important to predict the level of tool wear generated on the tool, to optimize the machining process. Many researchers have focused their efforts in tool wear studies, concluding that the cutting speed, feed, and the depth of cut are the parameters with most influence on this phenomenon. 2. Literature Review of Tool Wear Evaluation This review of tool wear literature is divided into three major categories which relate to the research areas carried out by the authors, together with a brief critique and identification of the research gap which the research in this article addresses. These three categories consist of: (i) Tool wear evaluation via empirical experimental machin- ing. (ii) Tool wear evaluation via mathematical models. (iii) The application of Taguchi in tool wear evaluation. 2.1 Tool Wear Evaluation via Empirical Experimental Machining In 1997, Elbestawi et al. (Ref 1) performed some experi- ments using several grades of polycrystalline cubic boron Nitride (PCBN) ball-nose end mills with various types of edge for the high-speed milling of H13 tool steel. They concluded that the higher contents of cubic boron nitride (CBN) (90%) on PCBN tools are recommended for milling hardened tool steel and that the main mode of tool failure was classical flank wear. Koshy et al. (Ref 2) in 2002 machined AISI D2 (HRC = 58), using solid carbide ball-nose end mills and indexable inserts employing carbide and cermets tools. They concluded that chipping, adhesion, and attrition were, in general, the governing mechanisms responsible for tool wear and that PCBN tools failed by fracture of the cutting edge. However, a better surface roughness was obtained with PCBN end mills. Tool wear mechanisms of a HSS cutting tool were also studied by Hogmark (Ref 3). They concluded that it is usual to find the presence of two wear mechanisms on the cutting tool and that the abrasive tool wear can be classified as medium and severe. At high cutting speeds, the generation of temperature in the workpiece surface- cutting tool interface is increased, easing a strong adhesion between them. The tool strain is a consequence of a combination between cutting forces and temperatures due to the increase of the cutting speed during the machining process. The fatigue tool wear mechanism is generated due to an increase of the cutting speed during the machining process, and is produced due to intermittent cutting especially when combining high cutting speeds and the machining of a hard and ductile material. In 2002, Liu et al. (Ref 4) studied the wear patterns and mechanisms of cutting tools during high-speed face milling of different working materials such as: cast iron, 45# tempered carbon steel, and 45# hardened carbon steel. They demon- strated that lower CBN content in the PCBN tool is not suitable for the high-speed machining of steels with hardness less than 45 to 50 HRC and that it is necessary to select a higher CBN content PCBN tool (more than 90% CBN) in intermittent high- speed milling operations. Patricia Mun ˜ oz-Escalona, Nayarit Dı ´az, and Zulay Cassier, Universidad Simo ´n Bolı ´var, Meca ´nica, Edf. Meu. 3er Piso. Valle de Sartenejas, Caracas 1080, Venezuela. Contact e-mail: pmunoz@usb.ve. JMEPEG (2012) 21:797–808 ÓASM International DOI: 10.1007/s11665-011-9964-6 1059-9495/$19.00 Journal of Materials Engineering and Performance Volume 21(6) June 2012—797