An Investigation into some Problems of Finished Vehicle Body Shell Production at Pressed Steel Fisher Ltd

Abstract

This thesis deals with some of the major problems involved in painting and trimming motor vehicles at a particular production unit of British Leyland. These problems were identified as :- (a) the procurement of sufficient quantities of component parts to fulfil a demand. (b) the allocation of the available stock to meet some objective when the supply of parts is interrupted. (c) the sequencing ‘and control of the painting and assembly functions. On the question of material procurement it was found that there was a remarkable lack of communication, on a sufficiently detailed level, between the sales organisation and the satellite production units. Vehicles were scheduled by the Sales Organisation for which there was insufficient stock and there were vehicles unscheduled, for which stock was available, and therefore could have been produced. Two stages of a solution are suggested. Firstly to form a feed forward information loop in terms of a formal communication link between sales and the provisioning organisations in order that future demand patterns can be detected and material provisioned accordingly. The next stage is to use a linear programming model to test various purchasing and order scheduling strategies prior to fixing a firm demand. The second problem area involved allocating the stock on hand, which due to extraneous factors may well not be of the ideal level, to meet some management objective. The problem was beyond manual solution and the technique of mathematical programming was used to determine optimum solutions. The problem was strictly an integer programming one but a technique was developed constraining a normal linear approach to give acceptable results without the unpredictability found with a pure integer technique. The solution produced an ‘optimum build program and illustrated strategies which could lead to an improvement in the objective. The third and final problem area investigated involved studying the reactions of the production system with the aid of a computerised simulation model. The model was found to be an accurate representation of the actual system and sensitivity testing indicated changes in strategy which would result in an improvement in production efficiency. These points were developed further and a strategy is submitted which will result in an improvement in the efficiency of the production system.