Materials Grindability

A physical description of material grindability is proposed as a property of deformation and surface destruction of processed surface at the envelope removal. A mechanism for microchip formation is described, which consists in changing mobility of the metal being grinded in “abrasive grain -workpiece” contact, which leads to uneven removal of the energy transmitted by abrasive particle. Criteria for assessing the grindability of metals and methodology for their determination are given. In this article, we described an automated measuring complex (AMC “Grinding”), which was developed, designed and tested by us. This complex is used to solve the aim of the monitoring of grinding process at all stages of abrasive treatment and gives the opportunity to make the adjustments at all stages of the technological process, taking into account both the properties of the abrasive tool and the properties of lubricating and cooling technological means and treatment regimes. The principle of operation of an automated complex is based on statistical analysis of output energy parameters of technological equipment operation. The proposed method for evaluating grindability has been experimentally tested when grinding parts of bearings under production conditions. As a result of processing the obtained data, rational tool characteristics and grinding modes were assigned, providing the required quality indicators

Mechanism of Chip Formation Process at Grinding

The mechanism of chip formation process at grinding is described, which involves a high-speed interaction of abrasive grain and metal, which leads to a concentration of thermal energy in front of the dispersing element (grain), causing a locally concentrated shift in the metal microvolume. In “abrasive grain -metal” contact a dissipative structure is formed which existence is supported by exchange of energy and substance with environment. Due to shock compression of the metal microvolume with abrasive grain, shock-wave heating is realized, initiating emission of electrons ionizing the lubricating cooling fluid in the zone of formation of side micro-scratches left by abrasive. The results obtained in the course of the research can be used to explain the mechanisms of chip formation, as well as the course of the physical and mechanical processes occurring on the surface layers of the grinded workpieces. By controlling chip formation processes at high-speed grinding, by optimally selecting the appropriate ratios between cutting speed and other processing parameters, a reduction in process thermal density can be achieved, which, with the highest productivity, will allow to obtain the required quality of the surface layer of the workpieces and a given dimensional accuracy