Hargovind Soni

TiNiCo shape memory alloy is most popular shape memory alloy for biomedical applications due to their outstanding properties such as shape memory effect, pseudoelasticity and transformation temperature. Machining of such kind of alloys is very difficult through conventional machining process is very difficult because they may affect their internal properties of these alloys. However conventional machining processes give poor surface quality during the machining hence non-conventional machining processes such as (wire electro discharge machining, water jet machining and electro discharge machining etc.) are more suitable for machining of such kind of alloy. From the literature it has been found that Wire electro discharge machining (WEDM) is more suitable non-conventional machining process for such kind of alloy. Present study exhibits the effects WEDM characteristics of Ti 50 Ni 45 Co 5 shape memory alloy. L-9 orthogonal array has been created by using Taguchi as a design method for machining of selected alloy and machined surface characterization has been carried out at the optimized process parameters with respect to microstructures, surface topography, microhardness, XRD analysis and residual stresses. To find the optimum setting of the input process parameters a couple of optimization techniques are used, namely principal component analysis (PCA) and Gray relational analysis (GRA) technique. 125μs pulse on time (T on), 35μs pulse off time (T off) and 40V servo voltage (SV) were found as an optimal setting for the higher material removal rate (MRR) with better surface roughness (SR) in the present study. Moreover, characterization of the machined surface is performed with respect to microstructures, surface topography, microhardness analysis, XRD and residual stresses. Harder surface observed near the cutting edge and TiNio 3 Tio 2 and CuZn were noticed on the surface of machined component through XRD analysis. However, compressive residual stress has been noticed on the machined surface during WEDM process. Keywords Shape memory alloy · Wire electro discharge machining · Optimization and machined surface characterizations

Wire electro-discharge machining is one of the advanced machining processes which can machine all conductive materials without changing their internal properties. Pulse on time and servo voltage are the most influential process parameters of wire electro-discharge machining. In the present study, attempts have been made to study the effects of these process parameters on the machined surface of Ti 50 Ni 49 Co 1 shape memory alloy by adopting a two process parameters experimental design approach. Cutting speed and surface roughness were considered as output parameters; surface crack density, microhardness and XRD analysis were carried out at the higher and lower values of these parameters. Higher surface crack density has been found at high values of cutting speed (125 μs pulse on time and 20 V servo voltage) while it is lower at the lower value of cutting speed (105 μs pulse on time and 60 V servo voltage). Moreover, a harder surface was found near the machined surface. By XRD analysis it was found that the crystal size of the WED machined surface was reduced at high T on and lower SV.

Shape memory alloys (SMAs) are unique class of smart materials with excellent physical, mechanical and biomedical properties, which have wide applications in several fields such as aerospace, robotics, biomedical, and dental etc. These alloys are well known for exhibiting shape memory effect (SME) and pseudoelasticity (PE), it is a well-established fact that they are required to be processed into functioning parts. The conventional machining affects the internal properties of shape memory alloys and hence, it is reported that nonconventional machining techniques are more suitable. Wire electro discharge machining (WEDM) is one of the nonconventional machining processes for machining complicated shapes without hampering the internal properties of such type of materials. In the present experimental investigation, wire electro discharge machining of Ti 50 Ni 40 Co 10 shape memory alloy (SMA) has been carried out and machining performances such as surface roughness (SR), and material removal rate (MRR) have been evaluated. Experimental results exposed that pulse on time, pulse off time and servo voltages are most influential process parameters on the responses. The machined surface has been charac-terised with respect to microstructure, microhardness, and phases formed.

This paper proposes a arrangement of Response Surface Methodology (RSM), Gray Relational Analysis (GRA) and Principal Component Analysis (PCA) used for optimizing the Electrical Discharge machining responses, such as material removal rate, surface roughness, and Radial overcut (ROC). The input parameters considered for this analysis are pulse current (Ip), discharge time (Ton), Duty cycle (Tau) to see the effect on the responses. The PCA is used to compute the weight of the responses during the optimization. Subsequently, the effects of each of these input parameters are analyzed and presented. These results provide the information that how to control the parameters so as to get the maximum MRR without losing the surface accuracy and tool accuracy. These values of this parameters are observed that Ip= 2A , Ton = 100 μs, and Tou = 80% are the desired optimal combination where the GRG value is maximum (0.771). which are the best combination of this analysis.

AISI D2 tool steel is a high-carbon and high-chromium cold-work tool steel alloyed with molybdenum and vanadium. It has many properties such as high wear resistance, high compressive strength, and high stability in hardening and good resistance to tempering back. The chemical composition of AISI D2 tool steel is (1.55 % C, 0.3 %Si, 0.4 %Mn, 11.8 % Cr, 0.8 % Mo, and 0.8 % V). The application of AISI D2 is Deep drawing and forming dies, cold drawing punches, hobbing, blanking, lamination and stamping dies, shear blades, burnishing rolls, master tools and gauges, slitting cutters, thread rolling & wire dies, extrusion dies etc. The unique features of this alloy have made it useful in all type of industries. Due to these characteristics this alloy difficult to perform machining by traditional method. Electro discharge machining is the one of the most machining, in which that material can be used. Purpose of this study is the effect of machining parameters such as pulse on time (T on), p...

This paper proposes a arrangement of Response Surface Methodology (RSM), Gray Relational Analysis (GRA) and Principal Component Analysis (PCA) used for optimizing the Electrical Discharge machining responses, such as material removal rate, surface roughness, and Radial overcut (ROC). The input parameters considered for this analysis are pulse current (I p), discharge time (T on), Duty cycle (Tau) to see the effect on the responses. The PCA is used to compute the weight of the responses during the optimization. Subsequently, the effects of each of these input parameters are analyzed and presented. These results provide the information that how to control the parameters so as to get the maximum MRR without losing the surface accuracy and tool accuracy. These values of this parameters are observed that Ip= 2A , Ton = 100 μs, and Tou = 80% are the desired optimal combination where the GRG value is maximum (0.771). which are the best combination of this analysis.

—Last few decades have a rapid growth in the development of harder and difficult to machine materials such as shape memory alloys, heat treated tool steels, composites, wasplloy, nimonics, carbides, stainless steel, heat resisting steels & many other high strength-temperature resistant (HSTR) alloys, which are widely used in aerospace, nuclear engineering, aeronautics, biomedical industries. It has been realized that such material are difficult to machine by conventional methods and to achieve required surface finish and material removal rate. Wire Electro discharge machining (WEDM) is a thermal erosion process where material is removed from the work piece by series of sparks between tool and workpiece immersed in a dielectric fluid. The present work aimed at determining the optimal process parameters for machining of Ti 50 Ni 39 Cu 11 (wt %) shape memory alloys on WEDM machine, where material removal rate (MRR) was maximized without compromising surface roughness (SR). The designed experimental results are used in the gray relational analysis & the weight of the quality characteristics are determined by the entropy measurement method. The effects of the parameters on the responses were evaluated by response surface methodology, which is based on optimization results. The best results for MRR and SR are achieved for the machining parameters of Pulse on Time (Ton) = 120μs, Pulse of time (Toff) =48μs, Spark Gap voltage (SV) =60v, Servo Feed (SF) =2180mu and Wire speed (WS) = 5mm/m.