Effect of grinding with different CBN grains applied to austempered ductile iron linked to quality and industrial cost

The grinding process consists of an essential stage of manufacture that is justified by the process’ ability to guarantee precise dimensions and provide an excellent surface finish. In the present study, two grinding wheels of cubic boron nitride (CBN) abrasive grains with different friability (GL and GS) were used to perform the cylindrical grinding of the austempered ductile iron (ADI). This work compared the individual performance of each wheel, with CBN GL being of low friability and CBN GS of high. During machining with three feed rates (0.5, 1.0, and 1.5 mm/min), the conventional lubri-refrigeration method was used. In the workpieces analyzed, the tests of surface roughness, roundness deviation, specific energy, G-ratio, acoustic emission, cost analysis, microhardness, confocal microscopy, and optical microscopy were applied. The tests showed that, in almost all the output parameters, the best results obtained were using the CBN GL wheel with less friability. However, in the analysis of acoustic emission and specific energy, the results presented that the GS wheel obtained the best results; as it is a more friable tool, the efforts applied during the grinding of the GS wheel are less. Also, the microstructure analyses showed that both wheels were able to carry out the process without causing changes in the workpieces’ mechanical properties. The cost analysis of the inputs showed that the increase in the feed rate produces the lowest cost.