Optimization of Surface Roughness Parameters by Different Multi-Response Optimization Techniques During Electro-Discharge Machining of Titanium Alloy

Optimization of Surface Roughness Parameters by Different Multi-Response Optimization Techniques During Electro-Discharge Machining of Titanium Alloy

Anshuman Kumar Sahu (National Institute of Technology Rourkela, India) and Siba Sankar Mahapatra (National Institute of Technology Rourkela, India)
Copyright: © 2019 |Pages: 27
DOI: 10.4018/978-1-5225-6161-3.ch004


In this chapter, the EDM process is performed by taking titanium alloy as work piece and AlSiMg prepared by selective laser sintering (SLS) process as tool electrode along with copper and graphite. The EDM is performed by varying different process parameters like voltage (V), discharge current (Ip), duty cycle (τ), and pulse-on-time (Ton). The surface roughness parameters like Ra, Rt, and Rz are measured by the use of surface roughness measurement machine. To reduce the number of experiments, design of experiment (DOE) approach like Taguchi's L27 orthogonal array has been used. The surface properties of the EDM specimen are optimized by desirability function approach, TOPSIS and VIKOR method, and the best parametric setting is reported for the EDM process. All the optimization techniques convergence to the same optimal parametric setting. The type of tool is the most significant parameter followed by discharge current and voltage. Better surface finish of EDM specimen is produced with lower level of parametric setting along with the use of AlSiMg RP electrode during EDM.
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Pradhan et al. have analyzed the average surface roughness of the EDMed surface by neural network models during EDM of AISI D2 steel work piece material (Pradhan, Das, & Biswas, 2009). Similarly, the surface properties like Ra, Rt and Rz are measured. The best optimal parametric setting is found out by using optimization techniques like VIKOR based Harmony search algorithm and desirability function approach to get excellent surface finish during electrical discharge coating and electrical discharge machining of AISI 1040 stainless steel and Nitinol respectively (Sahu, Mahapatra, & Chatterjee, 2017; Sahu, Chatterjee, Nayak, & Mahapatra, 2017). SLS process is use to prepare EDM electrode and the surface characteristics performance of the machined surface is studied during EDM process by taking Nitinol as work piece material (Sahu, Chatterjee, Nayak, & Mahapatra, 2017). Arthur at al. have used epoxy with silver paint and copper coating electrode prepared by rapid prototype process during machining of hardened tool steel to study the EDM performance of the electrodes. The thin-coated SL tool were rupture during machining where coating thickness is less than 180µm. However, electrode can used for semi-roughing or for finishing operations (Arthur et al., 2007). Different researchers have used SLS process to prepared EDM tool electrodes of different composition like bronze-nickel with copper phosphite, steel, phosphate and polyester as binder (Durr, Pilz, & Eleser, 1999; Zhao, Li, Zhang, Yu, & Zhang, 2003). Similarly, some other rapid tooling process are adopted to prepare EDM electrodes like abrading of SiC and corundum to prepare graphite electrode and copper and graphite electrodes by electroforming process and abrading process respectively (Tang, Hong, Zhou, & Lu, 2005; Ding, Lan, Hong, & Wu, 2004). From the previous works of the researchers, it was found that rapid tooling (RT) technology is a fast and effective technique to produce mold and RT has high prospective for decrease in time and cost.

Key Terms in this Chapter

Average Roughness (Ra): The Average roughness (Ra) is the arithmetic mean of the absolute values of the profile heights along the estimated length.

Maximum Height of the Profile (Rt): Maximum height of the profile (Rt) is the vertical distance between the highest and lowest points of the profile within the estimated length.

Selective Laser Sintering (SLS): Selective laser sintering process is an additive manufacturing (AM) technique used the powder fused based techniques to produce three dimensional components.

Electro-Discharge Machining (EDM): Electro-discharge machining is a thermo-electrical material removal process by the succession of electrical sparks.

Average Height of the Profile (Rz): Average height of the profile (Rz) is the mean of the consecutive values of maximum height of the profile (Rt) calculated over the estimated length.

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