Optimization of cutter geometry for deep milling of stump-containing peat deposit

This paper presents an experiment-based justification of rational geometric parameters for cutting elements of machines designed for deep milling of stump-containing peat deposits. A key challenge in this process is the presence of buried wood with the moisture content up to 64%, which causes a multiple increase in the dynamic loads and energy consumption. The study aims at determining an optimal cutter geometry that minimizes the specific cutting work under conditions of blocked cutting of an anisotropic medium. The methodology is based on comparative tests of rectangular, disc-shaped, and mushroomshaped cutters using a pendulum impact tester with the clearance angle varying from 0° to 18°. The kinematic and dynamic similarity between the laboratory setup and full-scale milling drums (MTP-41/44) was ensured, enabling extrapolation of the results using verified scaling coefficients. The results demonstrate that the rectangular cutter yields the lowest specific cutting work (179.15 kJ/m along the grain, 209.00 kJ/m across the grain), outperforming curvilinear counterparts by 7–10%. The optimal parameters were identified, e.g. the clearance angle α = 15°, the cutting angle δ = 60°, the approach angle φ = 75°, and the nose radius of 3 mm. It was shown that transverse fiber orientation increases the energy consumption by 16%, while raising wood moisture content to 64% increases the specific cutting work by a factor of 1.8. The data obtained make it possible to recommend the proposed geometry for the cutting tools of mass-produced peat milling machines, while the developed express assessment methodology enables tool design optimization without costly full-scale field trials.