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“EXCELLENCE THROUGH KNOWLEDGE” P A G E 75 A Study of Roughening the Surface of Sugar Cane Mill Roll Shells as Practiced in Jamaica This study examined the arcing process as practiced in all eight sugar cane mills in Jamaica. The findings show that the process is applied more as an “art”, rather than from a sound technical base. Hence, there exists a wide variation among and withinmills of how the process parameters are applied. There was no general standardization of the electrode, Voltage, current, angle, speed, polarity, condition (wet or dry). Mill roll shells are generally purchased without specification of the material composition. Suggestions of best technical practice for the process parameters are made compared to that found to be practiced in the industry. The process used to extract juice from sugar cane involves squeezing shredded cane between large rotating rollers. The roll shells are a composite assembly of an annular cast iron shell shrink fitted on to a forged steel shaft. The surface of the cast iron is roughened by an arc hard-facing process known as roll arcing, which produces discrete globules of hard metal on the apex and halfway on the flank of the teeth profile as shown in the exploded view of figure 1. This is done in order to improve the efficiency of juice extraction and maintain throughput by having the surface sufficiently rough to prevent slippage of the shredded cane as it is pulled into the nip region between the counter rotating mill rollers. The main objective of this study was to bring into focus the best practice for the arcing process in order to increase juice extraction with minimum wear at the lowest cost. This study has shown that far more needs to be done to enhance the life and efficiency of mill rollers. Specifications and standard practices do not exist to maintain high standards, reduce costs and improve efficiency. Where excessive wear or smooth mill roller surface exist; juice extraction and throughput can be greatly enhanced if the arcing process is standardized. The obvious benefits to be derived from better extraction are improved Factory Recovery Index and lower bagasse moisture with sustainable throughput. The water present in bagasse absorbs sugar, is of no calorific value and utilises heat in being vaporised during combustion. An improvement in the dryness of bagasse will increase its calorific value and consequently improved boiler efficiency. This will have a positive Gosset D. Oliver 1 & B. Wilson 2 1 Faculty of Engineering & Computing, University of Technology, Jamaica 2 The Sugar Industry Research Institute of Jamaica Gosset D. Oliver