Improving Grinding Ball Lifespan and Efficiency Through Hardenability Modelling and Optimization

Abstract

Grinding balls are spherical or cylindrical components used in grinding and milling operations to reduce the size of particles and achieve a finer product. They are made of high chromium white cast iron (HCWCI) and used in a variety of industrial processes. The efficiency of the grinding process is heavily influenced by the properties of the grinding balls, including their composition, size, and hardness. As such, there is ongoing research and development to improve the performance and durability of grinding balls, with the aim of countering the extreme conditions of wear and impact that cause a reduction in their lifespan. This study involved austenitizing balls with diameters of 50 mm and 70 mm at temperatures of 950°C and 1050°C, followed by quenching using both oil and compressed air. By exploiting the experimental HRC hardness results obtained in this work, the study aims to find a mathematical model relating the response (hardenability) to the main effects (austenitization temperature, quenching medium, and diameter balls) and their interactions. Analysis of variance (ANOVA) was used to establish the statistical significance parameters and an optimization of response by the best sub-models method and by the desirability function is realized in the second part of this work. It seems that the austenitization temperature and the size of the balls have a stronger impact on the hardenability of the balls than the cooling rate (quenching medium) by reducing the hardness difference between the surface and the medium of the ball to minimal values.