Evaluation of cutting forces in granite treated with microwaves on the basis of multiple linear regression analysis

The current study is focused on the evaluation of cutting forces in granite treated with high-power (24 kW) microwave radiation based on a multiple regression analysis. As a result, dependencies of forces acting on a conical cutting pick on the irradiation time (up to 45 s), the spacing between cuts and the distance from the treated surface (in depth) were established. The values of obtained correlation coefficients are in the range from 0.90 to 0.98. The analysis of the regression models show that the noticeable reduction in cutting forces for granite used in cutting tests is achieved after its irradiation with a minimum of approximately 34 s. Cutting forces increase linearly with increasing distance from the initially irradiated surface (in depth). For an irradiation time of 45 s, the influence of cracks induced by microwaves is levelled out at the depth of 32 mm, so the treatment of the rock used in cutting tests should be repeated after cutting of some 30 mm in order to initiate a new set of cracks for subsequent layers. Representation of cutting test results in form of regression dependencies allow a more detailed analysis of the influence of irradiation and cutting parameters on the cutting forces as well as more convenient re-use of the obtained empirical data by researchers and engineers.