Faculty Publications

Now showing 1 - 4 of 4

Experimental investigations on performance characteristics in wire electro discharge machining of Ti50Ni42.4Cu7.6 shape memory alloy
(2013) Narendranath, S.; Manjaiah, M.; Basavarajappa, S.; Gaitonde, V.N.
This article investigates the effect of pulse on time, peak current and pulse off time on wire electro discharge machining characteristics of Ti 50Ni42.4Cu7.6 shape memory alloy. A Ti 50Ni42.4Cu7.6 alloy was prepared by conventional tungsten arc melting. The machining experiments were performed as per Box-Behnken design on computer control wire electro discharge machining machine using molybdenum wire electrode. The relationships between the process parameters (pulse on time, peak current and pulse off time) and wire electro discharge machining responses (surface roughness and material removal rate) have been established using response surface methodology-based quadratic models. The analysis of variance has been employed to test the significance of the developed second-order mathematical models. The parametric analysis-based results reveal that low peak current with prolonged pulse on duration leads to reduced surface roughness. However, combination of low peak current with low pulse on time is beneficial for achieving better material removal rate for machining of shape memory alloy. © IMechE 2013.
Selection of optimal process parameters in ball burnishing of titanium alloy
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2014) Revankar, G.D.; Shetty, R.; Rao, S.S.; Gaitonde, V.N.
The current study deals with the analysis and optimization of the ball burnishing process of titanium alloy (Ti-6Al-4V). The Taguchi method was employed to determine the best combination of ball burnishing process parameters - such as burnishing speed, burnishing feed, burnishing force and number of passes - to minimize surface roughness and maximize hardness. The dry burnishing experiments were planned as per L9 orthogonal array (OA,) and signal-to-noise (S/N) ratio was applied to measure the proposed performance characteristics. Analysis of means (ANOM) and analysis of variance (ANOVA) were carried out to evaluate the optimal levels and to obtain the level of importance of the burnishing parameters, respectively. Validation tests with optimal levels of parameters were performed to illustrate the effectiveness of Taguchi optimization. The optimization results revealed that burnishing feed and burnishing force are the significant parameters for minimizing the surface roughness, whereas number of passes and burnishing force play important roles in maximizing the hardness. © 2014 Taylor & Francis Group, LLC.
Analysis of surface roughness and hardness in ball burnishing of titanium alloy
(Elsevier B.V., 2014) Revankar, G.D.; Shetty, R.; Rao, S.S.; Gaitonde, V.N.
Ball burnishing is a popular post-machining metal finishing operation. An attempt has been made in this paper to optimize the process parameters during burnishing of titanium alloy (Ti-6Al-4V). Ball burnishing process parameters such as burnishing speed, burnishing feed, burnishing force and number of passes were considered to minimize the surface roughness and maximize the hardness. The lubricated ball burnishing experiments were planned as per L25 orthogonal array and signal to noise (S/N) ratio was applied to measure the proposed performance characteristics. The validation tests with the optimal levels of parameters were performed to illustrate the effectiveness of Taguchi optimization. The optimization results revealed that burnishing feed and burnishing speed are the significant parameters for minimizing the surface roughness, whereas burnishing force and number of passes play important roles in maximizing the hardness. The optimization results showed greater improvements in surface finish (77%) and hardness (17%) when compared to pre-machined surfaces. © 2014 Elsevier Ltd. All rights reserved.
Effect of electrode material in wire electro discharge machining characteristics of Ti50Ni50-xCux shape memory alloy
(Elsevier Inc. usjcs@elsevier.com, 2015) Manjaiah, M.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.N.
Abstract TiNiCu alloy belongs to new class of shape memory alloy (SMA), which exhibits superior properties like shape memory effect, super elasticity and reversible martensitic transformation phase and thus find broad applications in actuators, micro tools and stents in biomedical components. Even though, SMA demonstrates outstanding property profile, traditional machining of SMAs is fairly complex and hence non-traditional machining like wire electric discharge machining (WEDM) has been performed. Hence, there is a need to investigate the WEDM performance characteristics of shape memory alloys due to excellent property profile and potential applications. In the present investigation, various machining characteristics like material removal rate (MRR), surface roughness, surface topography and metallographic changes have been studied and the influence of wire material on TiNiCu alloy machining characteristics has also been evaluated through ANOVA. Ti50Ni50-xCux=10, 20 was prepared by vacuum arc melting process. The proposed alloy as-cast material exhibits austenite property (B2 phase) and having higher hardness when compared to TiNi alloy. The investigation on WEDM of Ti50Ni50-xCux alloy reveals that the machining parameters such as servo voltage, pulse on time and pulse off time are the most significant parameters affecting MRR as well as surface roughness using both brass and zinc coated brass wires. However, machining with zinc coated brass wire yields reduced surface roughness and better MRR and also produces less surface defects on the machined surface of Ti50Ni50-xCux alloys. © 2015 Elsevier Inc. All rights reserved.

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