Analysis of a stepped shaft in a rubber cracker machine

This paper presents a comprehensive failure analysis study of a stepped shaft in a rubber recycling factory. The investigation aims to identify the underlying cause of the shaft's failure and provide insights for enhancing the reliability and durability of industrial machinery. Through visual examination, scanning electron microscopy (SEM), mechanical characterization, elemental composition analysis using X-ray fluorescence (XRF), and finite element analysis (FEA), the study reveals the presence of low-cycle fatigue, primarily attributed to small surface imperfections. The macroscopic inspection indicates a high-stress concentration area where the shaft diameter changes. FEA results corroborate stress concentration in the failure region. Safety factor analysis suggests premature failure of the shaft. Further inspection reveals that misalignment of the shaft with respect to the ground leads to excessive vibration, potentially contributing to the low-cycle fatigue failure. To address this, a solution is proposed and implemented, involving correct alignment of a new shaft, reinforced fixation of the machine to the ground, and construction of a steel-reinforced concrete base. Subsequent operation of the rubber cracker machine with the implemented solution demonstrates successful prevention of shaft failures. The study highlights the importance of proper design, material selection, and operational considerations in enhancing the reliability of industrial machinery.