Ultrasonic measurement of the inter-electrode gap in electrochemical machining

Abstract During the process of electrochemical machining the dependency of the inter-electrode gap with time and process parameters can be used to determine process characteristics and to define the shape of the workpiece surface relative to the tool surface. Defining process variables to map out the required gap-time function requires the use of time-consuming iterative trials. In-line monitoring of the gap would enable process control and tool to workpiece transfer characteristics to be achieved (for ideal conditions) without the requirement to generate such parameter maps. This work explores the use of ultrasound applied as a passive, non-intrusive, in-line gap measurement system for ECM. The accuracy of this technique was confirmed through correspondence between the generated gap-time and current time data and theoretical models applicable to ideal conditions. Gap measurements are also used to demonstrate and quantify the degree of departure from ideal behaviour for an In718/chloride system as the electrolyte flow rate is reduced from 16 to 4 l min−1. The monitoring of the gap size has also been shown to be effective when determining shape convergence under ideal conditions, for the example case of a 2D sinusoidal profile.

[1]  J. McGeough,et al.  Temperature distribution along the gap in electrochemical machining , 1977 .

[2]  R. R. Cole,et al.  Electrochemical Machining—Prediction and Correlation of Process Variables , 1966 .

[3]  Jb Hull,et al.  Development of a novel ultrasound monitoring system for container filling operations , 2001 .

[4]  M. A. Béjar,et al.  On the determination of current efficiency in electrochemical machining with a variable gap , 1993 .

[5]  R. H. Nilson,et al.  Free Boundary Problem for the Laplace Equation With Application to ECM Tool Design , 1976 .

[6]  Vijay K. Jain,et al.  Tooling design for ecm , 1980 .

[7]  R. R. Cole,et al.  Prediction of the One-Dimensional Equilibrium Cutting Gap in Electrochemical Machining , 1969 .

[8]  H Shirvani,et al.  Theoretical and computational investigation of the electrochemical machining process for characteristic cases of a stepped moving tool eroding a plane surface , 1997 .

[9]  Charles W. Tobias,et al.  On the Conductivity of Dispersions , 1959 .

[10]  R. D. Zerkle,et al.  Analytic determination of the equilibrium electrode gap in electrochemical machining , 1969 .

[11]  Frank Mill,et al.  A direct analytical solution to the tool design problem in electrochemical machining under steady state conditions , 2000 .

[12]  H Shirvani,et al.  Analysis and Computer Simulation of the Electrochemical Machining Process: A Stepped Moving Tool Eroding a Plane Surface , 1996 .

[13]  C. Bignon,et al.  Application of Eddy Currents to the In-Process Measurement of the Gap in E.C.M. , 1982 .

[14]  D Clifton,et al.  Theoretical analysis of chronoamperometric transients in electrochemical machining and characterization of titanium 6/4 and inconel 718 alloys , 2000 .

[15]  D Clifton,et al.  The use of a segmented tool for the analysis of electrochemical machining , 2001 .