Tomas Engström

Musculoskeletal Symptoms, Ergonomic Aspects and Psychosocial Factors in Two Different Truck Assembly Concepts

The project was carried out as a multidisciplinary correlational study of two truck-axle assembly systems (System A and B). System A (the old system) could be characterized as an unpaced line assembly system, whereas the change to the new system, System B, involved a parallelized system with longer job cycle time. The study included all permanent assembly workers in the two systems (System A 17 workers, System B 28 workers). The purpose of this study was to evaluate the two systems with respect to ergonomic factors, psychosocial factors and self-reported musculoskeletal symptoms. The job cycles were studied by means of video observation. Each subject answered a questionnaire regarding musculoskeletal symptoms and physical and psychosocial environment. The assemblers in System B were more satisfied with the physical work environment (e.g. noise, air), but less satisfied with the psychosocial environment, and the period prevalence of musculoskeletal symptoms was not lower, compared with the assemblers in System A. Video observation techniques showed that deep forward flexion was less common, but that the work was more hand intense in System B. In System B, neck/shoulder symptoms were associated principally with physical work (load) variables, whereas low back symptoms were associated with psychosocial variables.

Data collection and analysis of manual work using video recording and personal computer techniques

Abstract This paper initially reports on data collection and analysis of assembly systems including manual work using the so-called ‘loss analysis’ which we have applied within the automotive industry during two decades of research and development work. In the further development of this method of analysis we have during the last few years synchronized a personal computer and a video recorder, thereby facilitating data collection of true shop floor information, as well as developing the analysis procedure to also include ergonomic aspects and work performance in the analysis. This paper reports on: (1) the background, (2) the prototype equipment used for data collection and analysis which is illustrated by empirical data using the equipment to analyse stamping of sheet metal, as well as assembly of automobile doors and drivelines, and (3) how to integrate a ‘loss analysis’ with an ergonomic analysis of working postures (in this specific case using the so-called OWAS technique) studying assembly work on an automobile door. In this case we noted That the division of labour loss represents over 60% of the time consumption for assembly work. This analysis indicates that from an ergonomic point of view it is primarily worth studying what activities are included in the assembly work classified as OWAS work load level 2. Relevance to industry This paper describes and illustrates methods and equipment developed consisting of a synchronized personal computer and video recorder. This promotes a design based on empirical data for specific cases through facilitating the collection and analysis of shop floor information about manual work and process efficiency of interest for the design of assembly systems.

Production model discourse and experiences from the Swedish automotive industry

Discusses production models for final assembly in the automotive industry and also reports on the performance of one final assembly plant representing an innovative production model, namely the Volvo Uddevalla plant. Briefly considers some issues and pitfalls in current production model discourse, and in this connection introduces a distinction between two manufacturing models and broader industrial models. Describes two manufacturing models for final assembly work as namely the “serial flow model” and the “parallel flow model”. Discusses the Japanese “lean production”, sometimes synonymous with “Toyotism”, as an industrial model and the impact of socio‐economic and socio‐cultural contexts on manufacturing models and industrial models. Concludes that the Uddevalla plant highlights the paradox that long cycle time work in parallel flow assembly systems is in fact more efficient than short cycle time work in serial flow systems, provided that suitable technical and administrative preconditions exist. Therefore, the engineering point of view and the Swedish experiences of innovative manufacturing systems should be carefully considered in the current production model discourse.

A method for evaluation of manual work using synchronised video recordings and physiological measurements

Industrial interventions that focus on increased productivity may impair the ergonomics, on a workstation or individual level. This paper presents a method that characterises work time consumption and physical work load of manual work, using video recordings synchronised with physiological measurements of, e.g. muscular activity, and postures. The underlying idea was that it is possible to amalgamate technical and human aspects resulting in a synergetic evaluation. The method was developed through two case studies within the Swedish automotive industry, where manual materials handling was studied. A methodological result was that the synchronising procedure was sufficiently precise to allow work activities to be assigned significantly different levels of physical work load. These different levels may be used to predict physical work load in the design and change of production systems. It was concluded that the method is accurate enough to be a useful tool in industrial interventions.

Ergonomics in parallelized car assembly: a case study, with reference also to productivity aspects.

In 1985 Volvo started the development of a new plant for the assembling of cars. This plant was situated in the town of Uddevalla in Sweden. One deliberate aim with this plant was to combine an enhanced productivity and product quality with good ergonomics conditions and improved work organization. The plant was designed with a production system where parallel work-teams of about five persons could assemble from 1/4 up to complete cars. A newly developed tilting device, a piece of equipment that could rotate, rise and lower the car body in order to facilitate assembly work, was introduced. Ergonomic analyses of postural and musculoskeletal strain showed that parallelized flow production, according to the production principles of the Uddevalla plant, was superior to traditional car assembly according to the serial flow production concept, i.e. the traditional assembly line. It was noted that this ergonomic standard was implemented without compromising productivity. In conclusion, increased knowledge and experience of parallelized production systems has been gained which should be considered in the development of future assembly plants, even though the Uddevalla factory itself was closed down in 1993.

Reflective Production in the Final Assembly of Motor Vehicles – An Emerging Swedish Challenge

Presents some theoretical principles and empirical evidence relating to the new Swedish production systems for final assembly of motor vehicles. Contends that in these production systems it is possible simultaneously to enhance efficiency and quality of working life. Briefly sketches three production forms as they apply to the final assembly of automobiles and discusses the societal environments in which these different forms of production have evolved. Focuses on Volvo′s Swedish Uddevalla plant as one of the main examples so far of a reflective production system for final assembly of automobiles. Amplifies the analysis of different production flow patterns for final assembly and in particular addresses the issue of semi‐parallel mechanistic production flow and parallel organic production flow as alternatives to serial flow on a conventional line assembly.

A Swedish Industrial Research Program “Co-operative for Optimization of Industrial Production Systems Regarding Productivity and Ergonomics, COPE"

This publication was written during a period of time when we were engaged in an extensive research programme financed by the National Institute for Working Life in Solna (Cooperative for Optimisation of industrial production systems regarding Productivity and Ergonomics COPE).

Some Considerations Relating to the Reintroduction of Assembly Lines in Swedish Automotive Industry

In recent years, assembly lines have been reintroduced in the Swedish automotive industry and, in many cases, have replaced those so‐called alternative assembly systems which had their roots in the 1970s. This paper reviews and evaluates some explicit reasons given for the return to the assembly line. It also considers whether the decisions to replace alternative assembly systems with assembly lines may have been driven by other factors and mechanisms than those implicit in these arguments and, if so, what other factors could explain their reintroduction. There is also a discussion of which dimensions that should be taken into account when choosing between alternative assembly systems and assembly lines and empirical data are used to shed more light on the issues discussed in the article. The authors report one study that compares automobile assembly in an alternative assembly system with assembly of the same products after introducing an assembly line. They also briefly discuss reasons for and experiences from the recent introduction of alternative assembly systems in the Japanese electronics industry. In this case, so‐called cellular assembly systems have replaced assembly lines.

Sense of Coherence and Ill Health Among the Unemployed and Re-employed After Closure of an Assembly Plant

The aim of this study was to investigate the relationship between employment status, ill health and sense of coherence(SOC). A cross-sectional sample of the former workers at the closed down Volvo Kalmar plant in Sweden was used. A questionnaire was mailed to all identified subjects 2 years after the closure of the plant. Responses were obtained from 344 persons, of whom 173 were re-employed and 92 were unemployed. They answered the questionnaire anonymously on background variables, SOC and ill health (physical and psychological symptoms). A notable difference was found between the re-employed and unemployed, where the unemployed reported symptoms significantly more often as well as a significantly weaker SOC. A main finding in a four cell model indicated that unemployment had a rather low impact on symptoms in the presence of a strong SOC. Structural equation modelling (SEM) was performed with simultaneous analysis of the unemployed and reemployed. The SEM analysis indicated that SOC seemed to have a gre...

Empirical evaluation of the reformed assembly work at the Volvo Uddevalla plant: Psychosocial effects and performance aspects

Abstract This paper reports on the innovative, now defunct, Volvo Uddevalla final assembly plant. Theoretical frames of reference, the design process and empirical data on work group characteristics and working conditions are focused upon. Information regarding the Uddevalla plant has been gathered during a long-term co-operation project with the Volvo Corporation. During the closing-down period we obtained full access to all the production engineering data and personnel files available. We also had the opportunity of studying the responses to a questionnaire distributed to a random sample of blue-collar workers. Working conditions in Uddevalla in the form of psychosocial job factors are compared with industrial blue-collar workers in general as well as with assembly workers in the closed down Volvo Kalmar final assembly plant, which had a different, more traditional, production system. The paper also compares the psychosocial job factors, performance measures and work-group characteristics in the five assembly workshops in the Uddevalla plant. In comparing assembly workshops, the paper contrasts two approaches to competence development and work structuring used in Uddevalla, namely (1) giving priority to individual in-depth training of a specific task or (2) giving priority to a large competence overlap between individuals in a work group. Relevance to industry This paper reports and explains some results from a multidisciplinary evaluation of shop-floor work in the Volvo Uddevalla plant, a full-scale assembly plant with parallellized flow and long cycle time, using autonomous work groups. These experiences should be of general interest to industries searching for the factory of the future.