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