Super alloys have been used widely in all sectors (e.g., automobile, aerospace, biomedical, etc.) for their properties like high hardness, high wear, and corrosion resistance. A central challenge is the significantly higher temperature and pressure on the cutting tool, hence rapid tool wear and bad surface finish. In the present study, a FEM analysis has been developed to calculate the effect of preheating temperature on the surface of the workpiece on tool wear on machining Inconel 718. Usui's tool wear model has been implemented in DEFORM software. In order to validate the results, an experimental investigation has been carried out with same cutting conditions. The evaluated results were also compared with the room temperature machining condition. It was observed that the heating temperature increased the tool life by reducing tool wear, tool temperature compared to room temperature machining condition. The predicted tool wear, tool temperature, and chip morphology have been compared with the experimental results and good correlation was found.
TopIntroduction
The main difficulties in machining hard material like nickel and titanium based alloy is the rapid tool because of low thermal conductivity, strain hardening, and chemical reactivity to almost all tool. The economics of machining operation is mostly influenced by the tool wear (Ezugwu, 2005). As nickel base alloys are difficult to machine, resulting inhigher environmental burden. So the best sustainable practices have to be used in machining of nickel alloys as well as in an effort to reduce the carbon footprint and greenhouse gas emission(Pervaiz, 2015).The best way to machine these materials is to heat the workpiece before or during the machining operation. Different researchers worked using different heating sources. The most used heat source is laser source and studied by different researchers for machining of hard and composite materials. Shanmugan et al. (Shanmugam, Chen, Siores, & Brandt, 2002) studied the comparative study of jetting machining over laser machining technology for machining of composite materials. They study the kerf characteristics and surface roughness of two different materials, carbon composite and fibre reinforced plastic using an abrasivea wata er jet, plain water jet, and laser cutting. It was observed that abrasive water jet cutting promises a better cutting compared other. Li et al. (Li, Zheng, Lim, Chu, & Li, 2010) usedthe laser for machining of the carbonfibre reinforced composite. They found that heat accumulation could be used to increase material removal. Though laser source can be used for machining of hard materials, the set up cost is high. The simple heat source is flame heat source which can be used to heat for machining of hard material. Parida and Maity(A.K. Parida & Maity, 2016; A K Parida & Maity, 2016; Asit Kumar Parida, 2018; Asit Kumar Parida, &Maity, 2017)studied the machining of nickel base alloys using flame heating. They claimed that the heating enhanced the material removal rate, better surface finish, reduces the cutting forces, tool wear and increases the tool life. Maity and Swain (Maity & Swain, 2008) studied the hot machining of high manganese steel using oxy acetylene gas. Tool life increased with heating temperature in their work. Each heating source has some advantage and disadvantages. So the selection of proper heating source is necessary during hot machining. Otherwise, it may damage the surface of the workpiece material(N. Tosun & Ozler, 2004).
Though many analytical models had been used to predict the tool wear, due to some assumption like boundary conditions, simplified tool-workpiece configurations, and geometrical simplification needs to assigned(Haddag & Nouari, 2013). There are different types of tool wear such as abrasion (Thermo-mechanical), adhesion (BUE, welding), diffusion (due to high temperature) during machining of difficult-to-cut materials. In 1978, Usui et al. (Usui, Shirakashi, & Kitagawa, 1978) first developed the tool wear model to predict the tool wear using finite difference method.They used abrasive wear model to calculated the tool wear. The effect of preheating on cutting force, surface finish and tool wear on machining of EN-24 steel discussed by Thandra and Choudhary(Thandra & Choudhury, 2010). They observed that cutting force and thrust force was decreased in hot machining and surface finish improved compared to room temperature machining. Oliaei and Karpat(Oliaei & Karpat, 2016)discussed the tool wear affect the forces and tool deflection. Dogra et al. (Dogra, Sharma, Sachdeva, & Suri, 2012)reviewed the effect of nose radius, and different cutting edge preparation on tool wear, cutting force, surface integrity,etc.