Optimal work rest schemes and working hours in manufacturing environment: Balancing Interest 17th International Symposium on Shiftwork and Working Time, 18-22 September 2005, Hoofddorp, the Netherlands: program and abstracts

One of today's major challenges in manufacturing industries is the maximization of flexibility. One aspect of flexibility concerns the ability to deal with the fluctuations in the volume demand. Many companies are exposed to relatively short periods of times (about one or two months), where volume demands are significantly higher compared to the rest of the year. Temporary extra lines or extra shifts are relatively expensive solutions. It is preferable to temporarily modify the working hours and work rest schemes, specifically extend the working days and introduce alternating pause schemes. The question is how these measures would affect the worker and the production rates. In a series of experiments we tested the effects of alternating pause schemes and extended working days in different companies. This paper describes the results of an investigation into the effects of alternating pause schemes in one company (Philips DAP, a producer of shavers). This approach included the addition of two extra workers to a line of twelve workstations that are normally manned by twelve workers. Hereby, the operators are able to take their breaks alternately in couples of two. The advantage is that the line keeps running during the breaks. Another advantage might be that the total pause time per day for each worker was increased (1,2). Fourteen female operators took part as a subject. These operators were tested in three conditions. In the rational condition T, twelve operators were involved who took all breaks together. In the two alternative conditions A 1 and A2, fourteen operators took their lunch break all together, but all short breaks were taken alternately. The pause schemes were different across all three conditions resulting in pause times of 70, 80 and 85 minutes, in T, A 1 and A2 respectively. The new approach resulted in an increase in line output of 12 to 16% in A 1 and A2. On the operator level, we observed no differences in productivity, despite the differences in total pause time across conditions. Simultaneously, physical loads on the neck and shoulders, expressed by the level of discomfort, were found to be significantly lower in A2. A majority of the operators entitled this alternating break scheme as 'pleasant' (90%), but wanted the scheme to be applied only during the periods of peak demand because of social aspects (80%). In conclusion, an increase in volume flexibility can be achieved by adding two extra workers and by applying an alternating work rest scheme (and thus, without a costly reconfiguration of the line.) Meanwhile, the application of more pause time in A2, resulted in the experience of less discomfort by the workers, while the extra pause time did not lead to any reduction in productivity per worker, which is in line with previous observations.