Abstract: Because workers operating machines under mass production conditions frequently have extremely narrow, highly repetitive job contents which result in unilateral strains, a company manufacturing goods for the consumer industry sought to achieve job enrichment in this type of activity by introducing three different inspection tasks to supplement machine operation. A study of 12 workplaces using the Key Features Method, plus the IAD-BKA, OCRA- and RULA procedures and an energy expenditure calculation demonstrated the stress-reducing effect of the job enrichment concept. The EMG analyses performed on four selected muscles over a total of 12 full-shift working days also support the assumption that changes in types of stress will be beneficial. In contrast, the before/after-shift results obtained with the Nitsch Self-rating Scale and the NASA Task Load Index indicated increases in perceived strains and decline in motivation in all subjects – despite the job enrichment action. For this reason further ergonomic job redesign action is proposed.
Keywords: Job enrichment, study of stresses and strains, machine operation, quality control