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- Bao, Shihan, et al.
(författare)
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Ergonomic effects of a management-based rationalization in assembly work — a case study
- 1996
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 27:2, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- Due to unsatisfactory productivity, a large company in the Swedish manufacturing industry decided to rationalize their assembly system. The intended rationalization comprised several changes with deliberate ergonomic implications. The main aim of the present study was to evaluate the impact of the rationalization on the physical work load of the operators. The work load was assessed before and after the changes using expert observations, company records and direct technical measurements. The results indicate that the intervention led to only minor changes in muscle load, body postures and movement patterns. Several of the planned initiatives were never implemented, e.g. teaching the workers multiple skills and designing work stations at which a major part of the assembly sequence could be performed. This was mainly due to a policy revision caused by changes in the market situation. In spite of the company's original intentions, the revised production system contained only minor ergonomic improvements. Thus, the realization of the ergonomic potential in a rationalization seems to depend on management culture, as well as factors outside the company.
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| 3. |
- Bao, Shihan, et al.
(författare)
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Interactive effect of ergonomics and production engineering on shoulder-neck exposure — A case study of assembly work in China and Sweden
- 1997
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Ingår i: International Journal of Industrial Ergonomics. - 0169-8141 .- 1872-8219. ; 20:1, s. 75-85
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Tidskriftsartikel (refereegranskat)abstract
- Ergonomic improvements of work station design have been widely embraced as a measure for reduction of physical work load (mechanical exposure) and prevention or control of occupational shoulder-neck disorders. However, other elements of work rationalization, more in the hands of production engineers, may also influence the mechanical exposure. The present study concerns shoulder-neck exposure in a Chinese and a Swedish assembly line workplace. Interactive effects of ergonomic work station design, and production engineering (in terms of assembly line balancing and sensitivity of assembly line layout to production irregularities) on shoulder-neck exposure have been studied. It was shown that the Swedish workplace has a better ergonomic work station design, reflected in more favorable work postures during assembly operations. At the same time, the Swedish assembly line is better balanced and less sensitive to production irregularities, which probably reduces the total duration of idle time during assembly compared with the Chinese line. On the Swedish assembly line, arm movements are more frequent, and trapezius and infraspinatus muscle activation is more repetitive. Muscle activation levels are similar on the two lines. However, a larger proportion of low level muscle activities were found on the Chinese line compared with the Swedish line. On the basis of these results, it is suggested that the mechanical exposure of the assembly workers is a result of counteracting effects of improved ergonomic design of work stations and more effective production engineering.
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| 7. |
- Bao, Shihan, et al.
(författare)
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Prevalence of musculoskeletal disorders at workplaces in the People's Republic of China
- 2000
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Ingår i: International Journal of Occupational Safety and Ergonomics. - : Informa UK Limited. - 1080-3548 .- 2376-9130. ; 6:4, s. 557-574
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents 2 musculoskeletal disorders questionnaire surveys in 10 different Chinese occupational groups. Data collected from 1,603 workers using a modified Nordic musculoskeletal disorders symptom questionnaire showed that the 12-month prevalence of musculoskeletal disorders, particularly in the low back and shoulder-neck regions, was high at many Chinese workplaces. Significant differences existed between occupational groups. Assembly workers usually had higher neck-shoulder complaints compared to workers in most other occupations. However, the nature of assembly seemed also to influence the prevalence rate. Workers at a cassette recorder and a TV set assembly plant appeared to have more neck complaints compared with a group of thermos flask assemblers.
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| 8. |
- Bao, Shihan
(författare)
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Shoulder-neck exposure from assembly work and the significance of rationalization
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main purpose of this thesis was to investigate the implications of different rationalization levels of assembly work on shoulder-neck exposure. Three levels were studied: (1) a Chinese Tayloristic system, (2) a Swedish Tayloristic system, and (3) an assembly workplace rationalization in Sweden according to 'modern' rationalization principles including ergonomic purposes. A laboratory study was carried out to compare different electromyography (EMG) normalization procedures. It was found that different upper trapezius EMG normalization procedures may give widely differing load estimations. Translations between occupational EMG results normalized by different procedures may only be made at a very approximate level. A cross-sectional epidemiological study was carried out among 1603 workers among ten different Chinese occupational groups with an aim of providing prevalence data of musculoskeletal disorders. The results showed that the 12-month prevalence of musculoskeletal disorders, particularly in the low back and shoulder-neck regions, was high at many Chinese workplaces. Large differences of the prevalence rates occurred between different occupations. A more detailed follow-up study on one Chinese assembly line showed that, in general, the ergonomic working condition was not satisfactory according to general ergonomic principles. This appeared to cause poor working postures (upper arm flexion and abduction larger than 30° during a large proportion of the assembly cycle) and high 'static' upper trapezius load (= 5% Maximal Voluntary Electrical activation -- MVE). Further examination revealed that the Chinese assembly line was not well balanced and the assembly line organization was sensitive to production irregularities. This caused frequent breaks (idle time) between assembly operations and reduced total exposure time to the assembly operations. Compared with the Chinese line, the Swedish Tayloristic line had better ergonomically designed work stations which implied improved working postures on the assemblers. However, EMG amplitudes of the right upper trapezius and infraspinatus muscles did not decrease. This may be explained by a reduced idle time on the Swedish line due to an improved industrial engineering (better line balancing and less sensitivity to production irregularities). This hypothesis was supported by a further analysis of the EMG data, which showed that the Swedish subjects had less muscle activity of low amplitudes (< 2% Maximal Voluntary Electrical activation -- MVE), which may correspond to the idle periods, compared with the Chinese subjects. In the 'modern' Swedish assembly workplace, the realized rationalization led to only minor changes in most exposure parameters. Several expected exposure improvements were not observed possibly because a number of planned initiatives were never implemented after a policy shift of the company's management. For example, multi-skills were not provided to all assembly operators so that no actual job rotations were possible between different assembly stations. Only a few non-assembly tasks were introduced into the new assembly system and the operators still spent the majority of their time on assembly tasks, with the result that an expected varied exposure pattern was not seen. Based on these findings, it is concluded that ergonomic measures on work station design improvements may play an important role in improving mechanical exposure of assembly work. However, industrial engineering measures may also influence the mechanical exposure. Therefore, ergonomic implications of rationalization as well as the ergonomic potential of 'modern' rationalization should be considered in future studies of rationalization.
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| 9. |
- Bao, Shihan, et al.
(författare)
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The promises and problems of ergonomics application in the Peoples Republic of China
- 1989
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 20:4, s. 287-292
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Tidskriftsartikel (refereegranskat)abstract
- Ergonomics or human factors, as an applied science concerning the design of interfaces between man, machine and the working environment, has shown its great capacities and potentials for improving working conditions and efficiency during its applications in most industrially developed countries (IC). As a means of improving the economy, industrialisation has been initiated in many industrially developing countries (DC). Knowledge and technology available in ICs have been transferred to DCs in order to increase the process of industrialisation. Ergonomics as a western discipline has also been transferred to many DCs during the technology transfer process. As an example of the transfer and development of ergonomics in industrially developing countries, this paper examines the development of ergonomics and its various areas of application in the People's Republic of China. After reviewing the current ergonomics situation and its applications in China from various points of view - i e, from organisation, research, education and industrial application - promises and problems associatd with the development of this new area of science are discussed.
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