Machinability investigation and optimizing process parameters in ECM of stainless steel −12X18H10T for minimizing surface roughness

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Abstract

The tool and die applications are preferred the unconventional machining processes as they are popular in machining the difficult to cut type complex contour/ profile. The complex profile machined on hard material. Some special materials like Stainless Steel 12X18H10T withstand its inherent properties even it exposes at higher temperature. This investigation aims to expand its application by investigating its machinability in Electro Chemical machining process for surface finish. The process parameters like gap between work material and tool, discharge current, concentration of electrolyte and applied voltage at three levels. The Taguchi approach is used for optimizing the process parameters and confirmation runs also conducted for developing the mathematical modelling. For optimizing number of experiment the Taguchi L9 is utilized for this investigation.

Introduction

As considering its importance of significance of this material, the machinability study on this material on another unconventional machining process of wire cut Electric Discharge Machining is reported [1], [2]. [3] Experimented electrochemical machining of micro holes on stainless steel 304 work material. The complexing agents included along with neutral salt in the electrolyte to improve machining rate by 33%. [4] investigated 5 different stainless-steel work with chloride dielectric and studied dissolution valencies. [5] investigated the ECM of SS 202 work material by varying the distance between the anode and cathode. [6] examined overcut on ECM of I mm thick sheet of stainless steel, brass, and aluminium. [7] optimizedprocess parameters for ECM of square hole of size 12 μm × 100 μm in 0.1 mm thick sheet stainless steel-321. [8] introduced longitudinal vibration of electrode (pipe shaped) for drilling holes on 0.5 mm thick stainless-steel sheet. [9] recommended milling type ECM for complicated profile machining on stainless steel. [10] recommended ECM for micro machining including holes and intricated shapes. [11] also disclosed that machining like laser beam machining and Electric Discharge Machining are belongs to thermal machining and causes for heat affected zone but not with ECM.

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Section snippets

Materials and methods

The Stainless Steel 12X18H10T is preferred for this investigation. The process parameters like gap between work material and tool, discharge current, concentration of electrolyte and applied voltage at three levels. The surface roughness is measure of performance.

Experimental design

There are highly influencing Electrochemical machining parameters like Applied voltage (V), Discharge Current (C) Concentration of electrolyte (E) and the maintaining and the maintaining gap between work material and tool (G), considered as process variables in this investigation. the surface quality is measured by surface roughness (SR). The design of Experiments of 2nd order factorial (Fractional factorial design points) full fraction CCD with four factors at five levels with center points

Results and discussion

Design Expert 7.10 software is employed in this investigation, for determining S/N ratio, the lower the better is preferred as it is targeted for higher surface finish that is lower the surface roughness.

Most influential parameter on Surface quality

The percentage contribution of parameters on each response was obtained from analysis in Design Expert 7.10 software and the pie diagram (Fig. 7) was plotted in Microsoft excel as per obtained data. The Surface Quality (Ra) Results of ANOVA is furnished in the Table 7. In which DoF mean Degree of Freedom, SS mean Sum of Squares and MS is Mean Squares

Mathematical modeling for parameter Prediction

The result of factorial experiment, is utilizing to identify the most influencing parameter value for the surface quality. So, the factorial experiment was conducted by varying the most influential parameter values to obtain corresponding values for responses. The Discharge Current is most influencing factor on the surface quality. Five experiments conducted by varying the Discharge Current and corresponding surface quality value (Ra) observed, the average of three measurements of each

Conclusion

The surface quality aspect of machine-ability study on the12X18H10T - Stainless Steel work material in the process of ECM was investigated. Taguchi L9 orthogonal array based experimental design was derived as per number of process variables namely gap between work material and tool, discharge current, concentration of electrolyte and applied voltage at three levels. The experimented values utilized to perform the Taguchi Analysis and identified the most influencing factor is Pulse off Time. The

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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