Analytical Sizing and Modal Analysis Verification of Circular Saw Shafts

In circular saw machines used for cutting aluminum and PVC profiles, saw shafts are subjected to structural damage due to torsional moments, fatigue effects, and possible resonance. This study aims to determine appropriate material selection and perform analytical sizing for a safe, durable, and efficient shaft design under specified boundary conditions. During the design process, the mechanical properties of AISI 1040, 1050, 4140, and 4340 steels were compared. While analytical methods were used in the shaft diameter calculations, modal analysis was conducted using the “Half-power bandwidth” method to evaluate the dynamic behavior of the system and the risk of resonance. Analytical calculations revealed that the minimum safe shaft diameter for AISI 4340 steel, which has the highest strength among the evaluated materials, is 11.7 mm. As a result of the static analysis, the maximum shear stress occurring on the shaft was determined to be 4.2 MPa. Frequency analysis results confirmed that the system’s operating frequency of 50 Hz remains outside the critical resonance band.It was determined that the obtained minimum shaft diameter values are compatible with the existing shaft dimensions and meet safe design criteria. Consequently, the study demonstrates that in designing a safe saw shaft, geometric sizing alone is not sufficient; material properties must be evaluated together with static, fatigue, and dynamic behavior in an integrated manner.