WORK ANALYSIS AND LEARNING OF A COMPLEX TASK - STUDY OF THE KNIFE SHARPENING ACTIVITY IN A SLAUGHTERHOUSE

This study demonstrates the complexity and the requirements of knife s harpening. Results obtained during the first phase of the project show ed that training conditions are very demanding and that inadequate tra ining in Knife sharpening technique influences the health of workers a nd the quality of cutting. In the second phase, a better knowledge of the knife sharpening technique was acquired. The sharpening activity o f 15 workers was recorded on video. This led to identifiyng and charac terizing each operation of the knife sharpening cycle as well as the t echniques used. After interviews with two outside experts and three ex pert workers from the slaughterhouse, the conditions under which knife sharpening was carried out and the most important aspects of the task mastering process were identified. Sharpening proved to be a complex and important activity. Knife sharpening took up an average 10,7% on t he 10-minute observation periods and knife maintenance, an average 11, 4% of the work time. The findings showed first that various factors, s uch as tool quality, knife grinding, work station and work pace, influ enced knife sharpening; and second, that the knife sharpening activity could be decomposed into eighteen characteristics and performed using various techniques. Expert workers considered twelve of these charact eristics as the most important ones to master : frequency of blade sha rpening and washing, angle, pressure and movement of the blade on the steel rod, number of strokes on the steel rod, portion of the blade sh arpened, execution speed, visual attention, tactile sensation, steel r od position while being used and blade alternation. The workers observ ed had insufficient mastery of the different components of the knife s harpening process. None of them mastered all components and no compone nt was mastered by all. Only one third of the workers had enough tacti le sensation to be clearly informed about what was happening under the blade. Sharpening efficiency depends on certain difficult conditions over wich workers have little control. The development of knife sharpe ning training program and of favourable working conditions is necessar y if workers are to master the sharpening technique.