Improving blade accuracy via local electrochemical machining with partial insulated cathodes

Abstract

Electrochemical machining (ECM) has memory effect characteristics, which transfers the initial allowance unevenness to the final product, especially in conditions of small allowances such as in blades and blisks. This affects the machining accuracy and can lead to local overcutting. Thus, a two-step blade ECM method is proposed to solve this problem. The step 1 is local precise modifications using partial insulated electrodes, and. the step 2 is contour machining using conventional standard cathodes. Simulation investigations are performed to obtain different allowance distributions under various insulation widths. The relationship between the allowance distribution and insulation width dictates the most suitable insulation width in the step 1. To verify the effects of this method in blade machining with small allowances, experiments between the one-step and two-step blade ECM methods are compared. The experimental results show that the blade is overcut by 0.43 mm in the traditional one-step blade ECM method. However, for the two-step method, the allowance difference is reduced from 3.97 mm to 0.22 mm in the step 1, and a blade with the profile machining accuracy of −0.02–0.04 mm is machined after the step 2. Thus, the experimental results verify that the two-step blade ECM method is effective for blade machining with small allowances.