Selection of optimum conditions for maximum material removal rate with surface finish and damage as constraints in SiC grinding Anne Venu Gopal, P. Venkateswara Rao * Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110 016, India Received 4 March 2003; received in revised form 3 June 2003; accepted 10 June 2003 Abstract Efficient grinding of structural ceramics requires judicious selection of operating parameters to maximize removal rate while controlling surface integrity. Grinding of silicon carbide is difficult because of its low fracture toughness, making it very sensitive to cracking. In the present work, experiments were carried out to study the effect of wheel parameters; grain size and grain density and grinding parameters; depth of cut and feed on the surface roughness and surface damage. The significance of the grinding parameters on the selected responses was evaluated using analysis of variance. Mathematical models were developed using the experimental data considering only the significant parameters. A genetic algorithm (GA) code has been developed to optimize the grinding conditions for maximum material removal, using a multi-objective function model, by imposing surface roughness and surface damage constraints. The choice of including manufacturer's constraints on the basis of functional requirements of the component for maximizing the production rate was also embedded in the GA code. Keywords: Ceramic grinding; Surface roughness; Surface damage; Genetic algorithms 1. Introduction There has been an increased interest in the use of advanced ceramic materials in the recent past due to their unique physical and mechanical properties. The advan- tages of ceramics over other materials include high hard- ness and strength at elevated temperatures, chemical stability, attractive high temperature wear resistance and low density [1]. Structural ceramics such as silicon nitride and silicon carbide are now being increasingly used in bearings, valves, rotors and other applications where a close dimensional tolerance is required. Ceramic materials possess very low fracture tough- ness compared with metals and alloys. This means that they are very sensitive to the forces introduced due to machining. The major form of damage usually occurs as surface and subsurface damage. The first type of damage is due to radial cracks formed on the ground surface which are visible, and the later damage is due to median and lateral cracks that are formed below the affected grinding zone which are not visible [2]. Low thermal coefficient of expansion, low density and relatively high thermal conductivity are the special features of silicon carbide ceramics. In view of these properties, SiC is expected to be used increasingly for heat resistant parts [3]. Grinding is often the method of choice for mach- ining ceramics in large-scale production and automation. Despite various research efforts in ceramic grinding over the past two decades, much needs to be established to stan- dardize models for process optimization for improving product quality and increasing productivity to reduce machining cost. The effective use of ceramics in industrial applications demands the machining of ceramics with good surface finish and low surface damage. Therefore, in the present work, an attempt has been made to examine the effect of various process parameters and wheel proper- ties on these responses during grinding of silicon carbide with diamond abrasives. A genetic algorithm (GA) based optimization procedure has been developed to optimize grinding conditions, viz. depth of cut, work speed, grit size and density, using a multi-objective function model.