A computer model for investigating the relayout of batch production areas

Abstract

Abstract The requirement to be increasingly adaptable in methods of engineering production has brought forward the need to closely examine the methods and criteria used when changing from obsolete to new plant layouts within factories. The plant layout problem is particularly significant in the batch production environment, where a new generation of automated workcentres. more thorough analysis of product ranges via group technology orientated procedures and the wider application of flexible manufacturing methods results in higher rates of product obsolescence and a reduced effective life for manufacturing systems, In this paper, a computer simulation model is described which is designed to assist the layout engineer in scheduling the changeover from old to new layout. The changeover from initial to final layout within an existing production area is considered to take place in non–production intervals so as to exclude production time losses. Consequently, a limit is placed on the number of relocations per period, resulting in the possibility of interim layouts with lower efficiency of material movement existing before the final layout arrangement is achieved As relocation progresses, the layout engineer selects workcentres for relocation either by using a heuristic computer baaed minimum-cost selection or by manual input of alternative choices. The method of evaluating relayout strategies is a two-part model, contrasting the cost of relocating individual workcentres against the savings in materials movement, period by period, over the anticipated life of the layout. The model further examines the anticipated gains of relayout by contrasting costs at constant money values against discounted costs at specific rates of discounting. Comments and conclusions are drawn on the need, in general, for layout engineers to examine more closely the plant relocation problem. Specific comments are made with respect to four variables that can affect the financial viability of particular projects. Expected rate of return and relocation to movement costs levels are two of the financial variables which are examined. Limits imposed on the number of workcentre relocations per period and the expected life of a new layout arrangement are two of the manufacturing variables which are discussed.