Proposal for a Constraint Satisfaction Based Method for Capacity Management in uncertain Manufacturing Environments

The best way to disappoint your customers is to promise what you cannot maintain”. This sentence should remind companies to stick to reality, avoiding unreal promises that could result in customer’s dissatisfaction. This also means that when a company is requested to commit an order, it should check its potentiality in terms of available resources and already committed orders, in order to provide a realistic due-date. The complex set of activities devoted to manage the potentiality of the company against customers’ demand is referred with the term of capacity management. The problem of capacity management in industrial manufacturing companies has been tackled in various ways with the aim at defining the best due-date promise. For example the concepts of Available to Promise (ATP) and Capable-to-Promise (CTP) have been widely implemented. An emerging problem is that all these systems (as well as other purely mathematical models) show inadequacy and lack in managing production capacity in uncertain environments. This paper addresses the problem of production capacity management in presence of uncertain lead times (i.e. in presence of not fixed working time due to manual operations) by combining the characteristics of two different tools: the Constraint Satisfaction Problem (CSP) approach and the simulation. The final goal is to propose an efficient method in which the production system is represented by a CSP formulation, whose solutions are evaluated by means of a simulator in order to consider stochastic elements. The aim of the method is to allow an efficient evaluation of several scenarios under different types of uncertainties, supporting companies during the analysis of the needed production resources and in defining realistic due-dates.