Improvement of the manufacturing process of abrasive stones for honing

In the present work, the mixing process of different components of abrasive stones of cubic boron nitride used for rough honing was studied. Stones are made by the sintering process of abrasive grains, a metallic bond, and a humectant that favors covering of each abrasive grain by the bond. Incorrect mixing of abrasive grains with the bond and humectant can result in stones with nonuniform abrasive grain distribution. As the abrasive stone wears out, grain distribution will vary and modify efficiency of the honing operation. Tin is the metal having the lowest melting point among metals in the bond. By means of a scanning electron microscope and energy-dispersive X-ray microanalysis, tin segregation was discarded, which could have led to abrasive grain segregation. Later, mixing tests of the different components of the stones were performed at different mixing times. Both homogeneity degree of the abrasive content of different samples in a mix and covering degree of abrasive grains by bond were determined through two new parameters introduced in the present study. It was noted that use of a chain to accelerate the mixing process excessively reduces covering degree of abrasive grains even at initial mixing times. The highest quantity of humectant is recommended in order to get better covering degree. Mixing time should be high enough to assure homogeneity degree of the mix but low enough to avoid excessive reduction of covering degree.