Characterization of the size effect in grinding and the sliced bread analogy

The size effect is a well known phenomenon in grinding. The specific energy increases with decreasing depth of cut. A comprehensive explanation is therefore required to explain the size effect. In this paper, the size effect in grinding is reviewed and the proposition investigated that the size effect correlates with chip surface area. This effect is shown to be too large to ignore. It was found that the chip surface area created in grinding may increase by nearly 20% when the depth of cut is reduced by half. The effect of the density of the cutting edge distribution on the wheel surface is taken into account and is shown to be as important as the kinematic conditions of grinding. The density of the cutting edge distribution is influenced by the dressing conditions. A grinding power model is presented taking dressing effects into accounts. Grinding performance is comprehensively explained by the size effect and bluntness of the grinding wheel grains. The size effect is explained by the 'sliced bread analogy'. The characterization of the influence of grinding and dressing conditions on the size effect in grinding provides a basis to achieve improved control of the process.