Cranfield University at Silsoe (1975-2008)

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Browsing Cranfield University at Silsoe (1975-2008) by Supervisor "Baines, Tim"

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    Impact of human performance variation on the accuracy of manufacturing system simulation models
    (Cranfield University, 2004-10) Siebers, P-O.; Baines, Tim
    The research described in this thesis is concerned with human performance modelling as an aid in the process of manufacturing systems design and re-design. Most manufacturing systems are highly complex constructs and their behaviour is of a dynamic and stochastic nature. They have to be constantly designed and re-designed as organisations are continually being pressured to change their manufacturing facilities, technologies, methods, people and products. All design methods have some form of evaluation where discrete event simulation models are usually used to undertake a comparative analysis of different system designs. Within these discrete event simulation models it is common practice to represent workers as simple resources, often using deterministic performance values. Conversely, the work measurement literature indicates that worker task performance varies between different workers carrying out the same task and moreover for the same worker when repeating a task. The current approach of representing workers within discrete event simulation models ignores the potentially large effect that human performance Variation can have on system performance. This omission affects in particular simulation models of labour intensive manufacturing systems like manual assembly flow lines. It appears that this adds to the inaccuracy of the simulation model output and that consequently the simulation model does not react the behaviour of a real system in an appropriate way. A research programme has been designed to investigate these issues. First, a long term data collection exercise has been conducted to quantify the performance Variation of workers in a typical automotive manual assembly flow line. The data have then been used in form of frequency distributions to represent worker performance Variation at individual Workstations within manual assembly line simulation models. Through designed simulation experiments the impact that this form of worker performance Variation representation has on the accuracy of manual assembly line model behaviour has been investigated. Overall this research has found that adding worker performance Variation models into manual assembly flow line models has an impact on the accuracy of these simulation models. The magnitude of the impact depends very much on the type of Variation to be represented as well as on the system to be modelled. This evidence is an important result to support justification for further research in this area. For a more sophisticated approach of modelling worker performance Computational Organisation Theory using the multi-agent paradigm has been identified as the most suitable way forward.
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    Investigating the effects of the physical working environment upon direct manufacturing workers
    (Cranfield University, 2005-02) Mason, J. P.; Baines, Tim
    Within any developed nation a thriving manufacturing industry is a major driver behind economic prosperity. Key to maintaining a competitive manufacturing capability is the manufacturing system design process and the decisions made within it. The Ford Motor Company manufacturing design teams recognise that key decisions, regarding the physical working environment, can impact upon manufacturing workers, a key resource in maintaining competitiveness. The current problem centres on the lack of confidence among manufacturing system designers, in the tools and guidelines currently available to assess these effects. The working environment can be considered to consist of 'variable' factors (light, noise, temperature, etc.) and 'fixed' factors (equipment layout, hygiene facilities, resting areas, etc.). The aim of the research presented in this thesis, has been to identify the impact of the physical working environment upon manufacturing worker performance. Studies carried out within United Kingdom manufacturing facilities, provided an assessment of the impact of the variable and fixed physical working environment. The variable environmental factors were measured simultaneously against manufacturing worker performance and analysed for any relationships. The fixed environment factors were assessed to see whether their effect upon manufacturing worker motivation could be prioritised within a hierarchy. These studies have provided manufacturing system designers with the ability to make a more confident assessment of the physical working environment and its effect upon manufacturing worker performance. The contribution of this research is therefore, within the context of manufacturing system design, an improved understanding of the effects of the physical working environment upon the performance of manufacturing workers. Specifically, key findings identify the limits in which manufacturing worker performance is not affected by the variable working environment. Also identified, are a set of fixed environmental factors considered to impact the motivation of manufacturing workers. These findings are then used to present manufacturing system designers with a set of guidelines, that can provide assistance with the design of the physical working environment.
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    Understanding human variability to improve manufacturing system design
    (Cranfield University, 2004) Fletcher, Sarah; Baines, Tim; Asch, Rachel
    The way in which a manufacturing system is designed is a crucial determinant of its operational efficiency and profitability. System design is, therefore, a major consideration for organisations. However, the efficacy of current system design techniques could be improved. Designers still do not often construct assembly line layouts that provide the high level of efficiency and flexibility that is required by today's highly competitive organisations. One aspect of system design processes that has been found particularly deficient is the way in which human labour is considered. Current system design practices tend to disregard that workers may vary as they perform production tasks and the impact that this may have on the assembly line. In particular, system designers appear to have little understanding of how production work may be affected by workers' personal attributes. The research presented in this thesis sought to identify the nature and impact of human work performance to inform design stage practices. In particular, the research aimed to establish the extent to which the personal attributes of workers influence variations in their performance of production tasks. The research involved parallel data collection studies in a real manufacturing system where workers' performance of production tasks and their personal attributes in respect of work-related attitudes were measured and analysed. Overall, this research did not nd evidence of relationships between the particular work- related attitudes and production task performance that were measured in the study. However, indications were found that suggest production task performance variations may be produced by interactions between task characteristics and workers personal attributes. This evidence is an important development in understanding worker behaviour and informing manufacturing system designers that their neglect of worker performance variation in design stage evaluations may be a major cause of current design weaknesses.