Failure Investigation of the Driving Shaft in an Industrial Paddle Mixer

This study focuses on the failure analysis and structural evaluation of the shaft in a double-shaft paddle mixer, a vital component in industrial mixing processes used in food processing, fertilizer production, and pharmaceutical manufacturing. The mixer is designed to blend materials of different densities, sizes, and viscosities efficiently through a centrally mounted horizontal shaft that rotates inside a cylindrical chamber. The system includes paddles for agitation, feed openings for material input, and a discharge valve for controlled output. A primary concern in this research is the mechanical failure of the driving shaft, which transmits power from the motor via a gear drive. Structural weaknesses and failure mechanisms were investigated by analysing system pressure, bending moments, and externally applied forces. Stress distributions were computed to identify critical failure locations that could compromise the shaft’s integrity. A three-dimensional (3D) model of the shaft was developed using Pro-E software to enhance accuracy. Finite Element Analysis (FEA) was performed using ANSYS 13.0 to determine stress distribution, deformation, and failure-prone regions under operational loads. The numerical results were cross-verified with theoretical calculations based on ASME design codes to validate the structural adequacy. A shaft prototype was fabricated and tested under actual operating conditions to confirm the computational findings further. Experimental results closely matched FEA predictions, proving the effectiveness of the proposed design modifications. The optimised shaft exhibited increased durability, improved structural integrity, and enhanced performance. This research underscores the importance of virtual simulations before manufacturing, demonstrating how predictive analysis minimises failure risks. The study contributes to cost-efficient, time-saving design improvements, reducing material waste while ensuring the reliability of industrial mixing systems. These findings have broad implications for improving durability and efficiency in mechanical systems. Major Findings: The study identifies excessive bending moments, torsional stress, material fatigue, and improper loading conditions as primary causes of shaft failure. A FEA using ANSYS 13.0 was conducted, and results were validated through experimental testing, confirming the reliability of design modifications. The optimised shaft design enhances durability, structural integrity, and operational efficiency, reducing failure risks and improving industrial mixing performance.