Ergonomics at sewing workplaces

Status:

completed 06/2004

Aims:

An increased number of musculo-skeletal disorders are observed in connection with sewing workplaces; complaints from the sewers mainly concern the shoulder-arm-system. Poor ergonomics both as concerns the working means and the workplaces are considered to be at the heart of these disorders. Unfavourable work situations (posture while being seated, type of sewing machine used etc.) are suspected to affect the individual, physiological motion pattern such as to cause long-term negative consequences for the musculo-skeletal system. Wrong or excessive strain of the individual components (muscles, bones, joints and nervous system) may, in the long run, cause the symptoms summarised under the terms RSI (repetitive strain injury), CTD (cumulative trauma disorders) or WRMSD (work-related musculo-skeletal disorders).

Activities/Methods:

The study was conducted as an HVBG research project with the involvement of external research bodies (Munich Technical University and the Schwan engineering office in Frankfurt), and took the form of an ergonomic intervention study. Besides the external exposure factors, Munich Technical University also conducted an analysis of the strain situation at sewing workplaces. The Schwan engineering office developed ergonomic model sewing workplaces which were subsequently evaluated in practice in various sectors of the sewing industry. Eight enterprises in the sewing industry (shoes, industrial textiles, clothing, soft toys) took part in the study, which took the form of a field study. The existing situation regarding the tasks performed in these enterprises was studied at a number of typical sewing workplaces. The physical strain and the body posture assumed during sewing work were measured. The strain was measured by assessment of physiological parameters such as pulse rate and electrical muscle activity. The body postures and movements (spine, head, hand-arm-shoulder system, other extremities) were measured by means of the CUELA personal measurement system for computer-assisted measurement and long-term analysis of stress upon the musculoskeletal system. The ambient conditions were documented. The workers' subjective assessment of the strain was recorded, as were task-related complaints and disorders.

Results:

The results of these studies revealed stress factors, such as work performed with joints at extreme angles, static postures, repetitiveness, and in some cases high exertion at typical sewing workplaces. Significant causes for these factors are the demanding requirements for visibility as a function of the tasks, which necessitate observation at short distances, and workplaces of unsuitable design, which leave little freedom of movement. Based upon these findings, ergonomically improved sewing workplaces were developed for the identified areas. During this development process, consideration was given to the requirements of the companies concerned regarding the workplaces. The following characteristics are common to all variants of the new ergonomic sewing workplace: increased legroom and footroom, greater freedom of movement for foot/leg posture, facility for personal adjustment of the tabletop height and angle, facility for fast alternation between activity performed sitting and standing, armrests at the worktable with facility for personal adjustment, and changes in the foot-pedal/worktop arrangement at the sewing table. The sewing workplaces, developed in close co-operation with an industrial manufacturer, were tested and used in four of the eight businesses involved. Comparison of the stress/strain profiles revealed an improvement in spinal posture during work at the ergonomically optimized workplace, and reduction in postures involving extreme arm and shoulder joint angles. The reduction in physical strain was also measurable. Acceptance by the sewing personnel of the ergonomically redesigned workplace was high; the subjective assessment by the test subjects also confirmed the effect of reduced stress and strain of the modified working arrangement. The new ergonomic sewing workplace is now also available commercially. The methodology employed in the study for evaluation of the ergonomic intervention measures, which could also be exploited for ergonomic improvement of other workplaces, permitted precise and efficient quantification of the stress/strain situation.

Further informations:

Last Update: