In order to improve the power selection of the drive unit for the shredding machines, the authors determine the values of friction coefficients used in the cutting force models. These values consider the friction between steel and such wood-based materials as chipboard, MDF and OSB. The tests concern laminated and non-laminated external surfaces and surfaces subjected to cutting processes. The value of the coefficient of friction for the tested materials is in the range: for the static coefficient of friction 0.77-0.33, and for the kinetic coefficient of friction 0.68-0.25. The highest values of the static and kinematic coefficient of friction were recorded for MDF (non-laminated external surface) and they were equal respectively: 0.77 and 0.68. In turn, the smallest values of the discussed coefficients were recorded for chipboard (laminated external wood-base surface), which were at the level of 0.33 and 0.25, resp.
In order to elaborate design guidelines for developing efficient and possibly most energy saving mills for comminuting carpentry, OSB and MDF waste, there have been performed some tests aimed at torque demand on the working unit of the machinery participating in that process. The tests were carried out on a cylindrical wood chipper. There were indicated the maximum, minimum and average values of the torque, indispensable for the comminution of boards with defined geometric sizes (5 – 50 mm wide ) and thickness (3 – 28 mm). The value of torque required in the comminution of carpentry waste increases with growing cross section, and the torque vs. cross section relation is approximately linear. The presented values may constitute not only a set of input data indispensable for modeling the power which is necessary for the comminution process, but they can also enable the validation of the existing cutting models with a single cylinder cutter.