Investigation of electrochemical mill-grinding using abrasive tools with bottom insulation

Abstract

Electrochemical mill-grinding (ECMG) combines electrochemical milling and electrochemical grinding in one processing procedure, and can be used for machining difficult-to-machine alloys. Flatness of the machined surface is a basic requirement in industrial production, and a higher degree of flatness is always preferable. However, ECMG gives the machined surface a poor flatness, which leads to a larger machining allowance necessary for subsequent finishing. Hence, insulation treatments at the bottom of the abrasive tool need to be considered. In this paper, two insulation layouts are proposed. Simulation results show that the distributions of the current density concentrated area and electric quantity over the workpiece bottom depend on the conductive region distribution of the tool bottom. Experimental results show that the maximum feed rate is not affected by the tool bottom insulations during the machining of GH4169 alloy. The average depth of the machined slots decreases with reduction of conductive area ratios on the tool bottom. Furthermore, when using a lower applied voltage, the best flatness of the machined slots is achieved using the tool with the second insulation, whereas for a higher applied voltage, the best flatness is obtained using the tool with the first insulation. Finally, a sample with a 0.5-mm thickness thin-walled structure is fabricated at a feed rate of 2.1 mm min−1 and a depth of cut of 3 mm by the tool with the first insulation, and the material removal percentage of mechanical grinding is estimated to be 14.7%.