Lars Medbo

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.

Assembly work execution and materials kit functionality in parallel flow assembly systems

Abstract This paper reports on materials kit functionality — usefulness of the materials kit in respect of operators’ handling of materials and cognition during assembly work. That is, how the materials kit facilitates assembly work as well as promotes learning. This analysis comprises video recordings of nine automobiles in total from the closed down Volvo Uddevalla plant; a plant with parallel flow, long cycle time assembly work, where the materials supply was designed to facilitate the assembly work. To evaluate the usefulness of a materials kit from an assembly point of view, its configuration was related to the observed assembly work, and the level of structural congruence was estimated in order to judge to what extent the materials kit actually supported the assembly work. Briefly summarised, by using an analysis method in the form of ‘signal component’ methodology, this analysis showed that the assembly work proved to be almost identical when there were no technical differences between the layouts. It was thus assumed that it is possible to design materials kits in accordance with the observed assembly work, even though the materials kits configuration in the case study was not fully optimised and the stipulated work patterns were not in agreement with the observed work patterns. The ideal situation is that the operator picks components from one materials container at a time; however, it turned out that the operators picked from nearly two materials containers simultaneously. Relevance to industry Parallel flow, long cycle time assembly systems call for knowledge about conformity in the execution of assembly work within a work group. This paper reports on a case study focusing on the possibility to design common materials kits and assembly instructions, which in turn influences e.g. materials supply and learning times.

A case study of a principally new way of materials kitting - an evaluation of time consumption and physical workload

Abstract This article presents a materials kitting case study, using an alternative method for materials kitting: the traditional picker-to-material principle was replaced with a material-to-picker approach. The study was made in a materials supply workshop of an automobile plant shortly after this kitting process had been introduced. The materials kitting was video recorded and the material pickers’ physical exposure was assessed using ambulatory equipment to make an integrated registration of muscular activity, work postures and movements. The material pickers assessed work situations perceived as physically stressful. The materials kitting showed improved productivity as compared with other kitting methods. The study indicated that the work situation offered pickers low levels of physical exposure. The picking work was rather light but involved great repetitiveness in arm movements. The material pickers experienced the work as repetitive and having some physically stressful work situations. The integrated analyses showed: (1) that exposure in picking operations was similar to, but could be distinguished from, other work activities and (2) that picking from one type of storage package, Euro pallets, resulted in higher exposure than picking from plastic containers. More studies are needed on the implications of exposure levels in materials picking. Relevance to industry In the car industry, customer demands and manufacturers’ strategies result in the handling of many components in production systems. Materials kitting is one way to handle this and reduce costs for space and materials in progress. Traditional kitting methods are time consuming, and work-related musculoskeletal problems are common.

Impact of materials exposure on assembly workstation performance

This paper examines how the choice of materials exposure impacts workstation performance, in terms of non-value-adding work, space requirements and ergonomics. In a typical Swedish automotive setting, components are exposed in wooden pallets with frames beside the assembly line and supplied by forklift truck. In a case study, three workstations on an assembly line were studied and redesigned following the principles of lean production, using smaller plastic containers for the materials exposure. After the redesign, the space required for materials was reduced by 67%, non-value-adding work decreased by 20%, and walking distance was reduced by 52%. Furthermore, the ergonomics for the assembly operator improved greatly, with a 92% reduction of potentially harmful picking activities, thereby almost eliminating potentially harmful body movements. The theoretical contribution of this paper is firstly the development of an analysis model describing the impact of material exposure on workstation performance and secondly development of the existing categorisation of work operations to include different materials handling activities. The most important managerial implication is an increased understanding of the relationship between space, ergonomics, non-value-adding work and materials exposure. These findings have direct implications on workstation design in industry.

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.

The impact of materials feeding design on assembly process performance

Purpose - The purpose of this paper is to provide an understanding of how the materials feeding design at a workstation impacts the assembly process performance, in terms of manufacturing flexibility, process support, materials planning and work task efficiency. Design/methodology/approach The empirical data are based on two embedded case studies performed in close corporation with two Swedish automotive companies; additional observations from more than 20 company visits in Japan, and small-scale case studies performed in Japanese companies. To fully assess the work measurement figures, video recordings, work instructions and layout drawings were used to plot the operatorswalking patterns, and it was then possible to map the whole work cycle for an operator. Industrial engineers, anagers, group leaders, team leaders and operators were interviewed. Based on the literature review and personal experience from the small-scale case studies carried out in Japan, the existing assembly systemscomponent racks were conceptually re-designed. This led to two hypothetical assembly systems, which could be used for understanding the impact of materials feeding design on assembly process performance. The design of the new component racks and the choice of packaging types were made together with practitioners. Findings The paper shows that the design of component racks and choice of packaging types have a major impact on the assembly process performance. Component racks with a large depth and small width and tailored packages create important advantages over traditional Swedish component racks designed for EUR-pallets. Line stocking is not always the best choice for materials feeding, but this paper shows that line stocking, especially in Swedish assembly systems, can be improved. Sequencing can thus be reduced, resulting in fewer problems when there are sequence breaks in the production flow. Component racks with small packages and large depth increase the work task efficiency, volume, mix, new products and modification flexibility. For example, free space is an important issue for these types of flexibilities. Component racks that are portable and easy to rearrange, together with free space, greatly facilitate handling of new product introductions or modifications of products. The new and old component can be displayed and fed to the same workstation, and if there is a larger change a whole segment of a component rack can easily be replaced by a new one between work shifts. Research limitations/implications - The scope of the study is limited to the conditions at workstations. Consequences for the materials flow upstream (i.e. internal materials handling, warehousing, transport, supplier processes, etc.) are not included, but must in further studies also be considered to avoid sub-optimisation. Originality/value - The paper highlights the fact that a shift in focus is necessary when designing workstations with component racks in Swedish companies, meaning that operators become the customers rather than the transport company or materials handler.

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.

Kitting and time efficiency in manual assembly

The present paper focuses on parts presentation in manual assembly. Its aim is to determine how kitting affects the time spent by the assembler fetching parts and, more specifically, what is the impact of the proportion of parts included in the kit. The present paper is based on four case studies of automobile assembly, in which parts presentation by kitting is compared with parts presentation in component racks. In the case studies, kitting enabled shorter distances between parts presentation and assembly object and thereby a potential reduction in the time spent fetching parts. However, when only a proportion of parts were kitted, the time spent fetching parts was not always reduced, in spite of this potential. The present paper finds that when deciding which parts should be kitted, attention should be paid to how and in what order assembly operations are performed.