O estudante Fernando Moreira Bordin, orientado pelo Prof. Dr.-Ing. Walter Lindolfo Weingaertner e coorientado pelos Prof. Fabio Antonio Xavier, Dr. Eng. e Prof. Dr.-Ing. Marcio Celso Fredel, defenderá sua dissertação na próxima sexta-feira (06/09) às 9h30min no Auditório da EMC. A defesa é vinculada ao Programa de Pós-Graduação em Engenharia Mecânica. O auditório tem capacidade para 64 pessoas.
Título: “Importance of the knowledge of the real grinding wheel composition for grinding cycle optimization”
Cycle time reduction in cylindrical peripheral plunge grinding influences on the quality of the manufactured product. In order to obtain a component free of deleterious modifications to its performance and lifespan, it is a common practice in the industry to reduce the specific material removal rate which increases the process time. Thus, it becomes opportune to employ grinding cycles, with optimized roughing to finishing sequences, based on the knowledge of the damage depth on the ground subsurface during roughing, avoiding mechanical property’s modification on the final component, as well as obtaining reduced process times. Conventional grinding wheels with microcrystalline aluminum oxide abrasive ensure excellent wear resistance and tool dressing flexibility, however with effects on the subsurface still not completely understood. This study shows that to obtain more sustainable multi-step external cylindrical plunge grinding cycles for grinding with conventional grinding wheels, is of fundamental importance to acknowledge the real grinding wheel characteristics. Ring-shape quenched and tempered AISI 1040 steel workpieces, were ground with grinding wheels with different content of microcrystalline aluminum oxide (from 0%, up to 45%), employing specific material removal rates from roughing to finishing. The evaluation criteria were the grinding force and surface integrity. The results supply a database and help the determination of grinding cycles with optimized grinding time, constrained by the boundary-affected layer thickness and surface roughness of the component. The results initially obtained with the different microcrystalline aluminum oxide fraction seemed not to be consistent. The X-ray tomography revealed that the provided wheels without and with the lowest microcrystalline aluminum oxide content present a higher binder percentage than the wheels with the higher microcrystalline aluminum oxide content. The reevaluation of the results, considering the higher binder characteristic, allowed a consistent evaluation of the wear and grinding force results. The roughing cycle optimization up until the influenced material layer, to be removed on the finishing, allows reduction of the grinding times with the use of multi-step grinding cycles, however still requiring consistent reliable data. It is also concluded that the replacement of the conventional grinding wheels with grinding wheels containing microcrystalline aluminum oxide in the abrasive composition must consider the knowledge of the grinding wheel composition and structure to allow adequate prediction of its influence on the boundary-affected layer.
Palavras-chave: sol-gel Al2O3; X-ray tomography; boundary-affected layer; grinding cycles; dynamic programming.