The Layout of Workcentres in a Job Shop Situation.

Abstract

This thesis deals with an extended approach to the problems of rearranging the layout of workcentres within an existing job shop to suit a change in manufacturing conditions. Initially these problems are identified as: 1. The need to utilise an adequate representation of facilities and layout area. 2. The need to consider subjective and quantitative factors at a detailed level. 3. The influence of the overall manufacturing system on the arrangement of workcentres. 4. Whether in reality the benefits claimed of a layout arrangement are in practice obtained through the lifespan of the layout. To investigate these problems a two stage approach is suggested dealing firstly with the creation of static layout designs and secondly with the dynamic simulation of layout changeovers. The static layout model utilises materials movement as a quantitative criterion in an interactive designer-heuristic approach which firstly locates pregrouped sets of workcentrees and secondly locates individual workcentres within the areas allocated to each set. Having created an initial and a final layout arrangement an interactive simulation model is proposed for evaluating the changeover from initial to final layout under varying conditions. Features of the simulation model include: 1. A more complex but realistic evaluation of materials movement costs. 2. The use of workplace relocation and materials movement costs. 3. The use of a parallel present value financial analysis to account for the influence of time on costs. 4. An inbuilt automatic changeover heuristic. A computerised suite of programs is then introduced to include these models, giving consideration to the best possible combination of equipment and program for the design process. Finally a number of the new parameters introduced are examined using an industrial test case and conclusions drawn on their behaviour, with test results presented to support these.