A condition based maintenance approach for a rotary drum crop shear

Abstract

An alternative solution was proposed to the current replacement strategy employed to maintain the rotary drum crop shear at ArcelorMittal South Africa (AMSA) Vanderbijlpark Hot Strip Mill (HSM). Process and production characteristics were also considered in an attempt to optimise the expected crop-shear blades’ lifetime. Ineffective management of assets led to unpredictable performance and costly cessations in the production. Focus was placed on improving the reliability of the crop shear while mitigating the maintenance and operating costs, and thus striving towards a more efficient way to produce flat steel products at the HSM. A universally applicable condition based maintenance (CBM) approach was considered as an alternative replacement strategy for the rotary drum crop shear at the HSM. The impact of current process and production methods was also analysed, identifying areas in the operation that lack sustainability. The execution of the proposed remedy strategies was monitored thoroughly to assess and validate its effective outcomes. Replacements of crop shear cartridges yielded an extremely erratic trend; hence the unpredictability noticed early in the present study. The volatile performance often resulted in a reactive strategy to replace the cartridges. The proposed CBM approach was favoured for its ability in maximising the life duration of the crop-shear blades and eliminating the occurrence of breakdown replacements. The offsets of the crop shear cuts, speed configuration of the crop shear and the practice of making manual cuts, were indicated as factors contributing to the current poor performance of the crop shear. The modification of these components prolonged the life expectancy of the crop-shear blades. The validated findings of the crop shear performance yielded the best-ever recorded performance at the HSM. A reduction in operating and maintenance costs of the crop shear, improved reliability of the crop shear’s operation and thus also of the plant, are the major actual benefits initially anticipated. The topic of the study was considered to be a globally familiar application and, therefore, contributed to the body of knowledge in this field, from which other operators and maintenance consultants may benefit.