ORIGINAL ARTICLE Grinding wheel effect in the grind-hardening process K. Salonitis & T. Chondros & G. Chryssolouris Received: 10 August 2006 / Accepted: 30 April 2007 / Published online: 26 May 2007 # Springer-Verlag London Limited 2007 Abstract The grind-hardening process is based on the utilization of the generated heat in the grinding zone for inducing a metallurgical transformation on the surface of the ground workpiece. The workpiece surface is locally heated above the austenitization temperature and subsequently is quenched to increase surface hardness. A theoretical model was developed for the prediction of the heat-generation rate as a function of the process parameters and the grinding wheel characteristics. The model combined with a database of relationships among the heat entering the workpiece, the process parameters, and the hardness penetration depth (HPD), which was presented by the authors in an earlier publication, allows the assessment of the grinding wheel’ s effect characteristics on the hardening output of the process. The experimental results have verified the predictions of the theoretical model and served for its calibration. Keywords Grinding . Grinding wheels . Surface hardening . Grind-hardening . Process modeling Abbreviations CCT Continuous cooling temperature FEA Finite element analysis HPD Hardness penetration depth Nomenclature A a Actual area of contact (mm 2 ) A g Wear flat area (mm 2 ) a 1 , a 2 Experimentally defined coefficients a e Depth of cut (mm) b Grinding wheel width (mm) c Specific heat (J/kg.K) d Diameter (mm) e ch Specific energy convected by chips (J/mm 3 ) F t Tangential component of the cutting forces (N) HPD Hardness penetration depth (mm) i Effective value of thermal composite properties k Thermal conductivity (W/m.K) k 1 , k 2 Experimentally defined parameters l c Geometric contact length (mm) m Calibrating factor (-) M Grain size number from the grinding wheel mark- ing (-) n Integer corresponding to hardness grade (-) n a Number of active grains (-) P Grinding wheel spindle power (W) p m Average contact pressure (N/mm 2 ) q Heat flux (W/mm 2 ) R Heat partition ratio (-) S Structure number from the grinding wheel marking (-) T Temperature (°C) u Speed (m/sec) u ch Specific chip formation energy (J/mm 3 ) V Volumetric concentration Greek letters and symbols β Coefficient of heat transfer (J/m 2 sK) ρ Density (kg/m 3 ) μ Friction coefficient (-) φ Surface density of the thermal composite (%) Subscripts a Air c Cutting Int J Adv Manuf Technol (2008) 38:48–58 DOI 10.1007/s00170-007-1078-9 K. Salonitis : T. Chondros : G. Chryssolouris (*) Laboratory for Manufacturing Systems and Automation, Department of Mechanical Engineering and Aeronautics, University of Patras, Patras 261 10, Greece e-mail: xrisol@mech.upatras.gr