Grinding Wheel Loading with and without Vibration Assistance

Introduction Due to its tool structure and composition, the grinding operation is considered the best machining process in the manufacture of brittle materials like ceramics. A grinding wheel distributes wear over many cutters and is capable of replenishing itself. However, the condition of the grinding wheel constantly changes as grits wear and chips accumulate in the spaces between grits. Therefore, wheel loading is one of the main factors limiting the capability of the grinding wheel. Chip accumulation (or loading) is particularly problematic with the fine grit wheels used in fine grinding of ceramics. Wheel loading results in an increase in grinding forces and temperature. As a consequence, the rate of abrasive wear increases and the surface finish of the workpiece deteriorates. In our previous studies, we have investigated the effect of wheel characteristics, such as concentration and grit size, on the grinding chip size. The literature indicates that the main cause of chip (or wheel) loading is adhesion between the active grits and the workpiece material deformed in the form of chips. Chips accumulate in the spaces between grits. Thus the relationship between chip volume and volume between grits is likely to influence the tendency for wheel loading. These quantities were investigated using a kinematic based simulation. Based on the grinding conditions and wheel characteristics, the simulation program calculates chip volumes. A higher ratio of Vbetweengrits/Vchip would reduce the tendency for chip accumulation. Our results indicate that the volume between grits grows more quickly than the volume of chips as the grit size increases and/or volume fraction decreases. This validates the common observation that fine grit wheels experience more chip loading than coarse grit wheels. In order to gain a better understanding of the mechanism of chip loading, we continued the study by examining the effect of vibration assistance.