Catastrophic failure of a raise boring machine during underground reaming operations

Abstract

This paper describes the investigation of the catastrophic failure of a raise boring machine used for underground reaming operations. The results of the investigation indicate that failure was due to the fracture of the 32 drive head bolts, 30 of which had failed as a result of corrosion-induced fatigue. Metallurgical examination confirmed that the bolts had been manufactured in accordance with the SAE J429 Specification. A number of recommendations have since been implemented by the mine, who has also introduced a quality system specifically for the control of drive head bolt sets. The equipment has now operated without problems for several years.