Hard gear finishing viewed as a process of abrasive wear

Abrasive machining is one of the key technologies in gear manufacturing. Amongst abrasive finishing processes of hardened gears, operations characterised by cutting speeds as low as 0.3–5 m/s have been becoming more and more important during the last 20 years. A lot of effort has been spent to increase the productivity of such low speed grinding processes. A part of this effort is the development of new abrasive tools, which involves much empirical investigation and is, therefore, very time and cost intensive. The present study is aimed at a deeper understanding of differences in the process behaviour of various grinding wheels. For this purpose, the grinding process has been analysed as a process of abrasive wear. The chosen research approach implied a combination of grinding experiments and analytical calculations. To characterise the process quantities and work results in grinding, an abrasive wear map was used. Furthermore, calculations of the maximum single grain chip thickness, the mean single grain normal forces and X-ray measurements of residual subsurface stresses were made. Results of the investigations show that at constant grinding conditions, the maximum single grain chip thickness determines the tool performance. Additionally, the essential work results in grinding have been observed to correlate with the overall friction coefficient in the contact area regardless of the used tool. These results can be advantageously used for both industrial development of new abrasive tools and further fundamental research.