DEVELOPMENT OF THE SETUP AND PERFORMANCE OPTIMIZATION OF ELECTRO-CHEMICAL HONING PROCESS

Abstract

The surface quality and shape deviations play a crucial role in determining the functional performance of critical engineering components during service. Hybrid electrolytic machining processes are gaining considerable attention from the manufacturing community in order to meet the challenges of stringent surface quality and size tolerance requirements, often coupled with high part production rates. Electro-chemical honing (ECH) is a hybrid electrolytic micro-finishing technology characterized by a distinct coupling of electro-chemical machining and conventional honing processes to provide controlled functional surface generation and fast material removal capabilities in a single operation. ECH can offer a unique range of benefits to the machined surfaces not obtainable by either of the processes when applied independently. In ECH, a low DC potential is applied across the electrolyte flooded inter electrode gap (IEG) between a cathode stainless steel tool and anode workpiece for anodic dissolution while the ECH tool, which also contains non-conductive honing sticks, is stroked through the work bore with a controlled generating motion of simultaneous rotation and reciprocation. Major part of the material removal occurs through electrolytic action while the mechanical abrasion by honing sticks is controlled to a minimum, just enough to remove preferentially the metal oxide microfilm from the higher spots protruding from the ideal configuration and resulting surface non-uniformity due to electrolytic action. The process has a flexi- feature with regard to the control of machined surface characteristics. A surface having a distinct cross-hatch lay pattern, required for oil retention, alongwith compressive residual stress desirable for the components that are subject to cyclic loading can be produced. A surface completely free from stresses can also be generated. ECH possesses the ability to improve surface finish as well as to correct form deviations and smooth off ripples. Surface roughness value Ra of the order of 0.05 μm and tolerances of t 0.002 mm can be achieved. The ability of ECH to apply these benefits productively, has led to its widespread use in many industries, especially in aerospace, auto, petrochemical reactor, roller, and gear manufacturing industries.