Machinability of cryogenically treated and non-treated Ti-5553 workpiece: a comparative study

TIMETAL (Ti-5553), a high strength, low density near beta titanium alloy is an upcoming material extensively used in the aerospace industry. In order to manufacture various parts from this super alloy, machining process comes to play. The present work focuses on the electro discharge machining of Ti-5553 a cryogenically treated workpiece (CW) and normal workpiece (NW). A comparative study has been carried out on the machining between normal workpiece (NW) and cryogenically treated workpiece (CW). The ease of machinability was measured in terms of three response parameters namely; material removal rate, surface roughness and surface crack density. The process control parameters involved in the experiment were open circuit voltage, peak current, flushing pressure, duty factor and pulse on time. A five factor and 4 Levels L₁₆ orthogonal array has been used and performed the experiments on both the workpiece (normal workpiece (NW) and cryogenically treated workpiece (CW). The TOPSIS, a Multi criteria decision making technique has been used to convert the multi response to single domain. The Taguchi method has been applied and the optimal parameter setting was obtained which yielded in the highest MRR, lower SR and lower SCD. The obtained optimal parameter settings of both the workpiece have been compared and the effects of cryogenically cooling the workpiece was quite impressive. A comparative analysis has been done and found improvement of surface morphology of the workpiece after cryogenic treatment. The study has been done using the scanning electron microscope. Thus, a brief theoretical study on the effects of cryogenic cooling along with the ease of machinability in titanium alloy has been discussed in this research work.