Some aspects of the input/output methods for managing work-in-process inventories

The aim of the present paper is to analyse some aspects of the input/output control (IOC) methodology with respect to the following important factors: (a) decision level and planning horizon and (b) form of production organization. The concept of IOC was originally advanced in connection with individual work centres at the shop orders release decision level and this is how it has been incorporated in some standard production planning and control computer packages (e.g. the module SOLAR of the COPICS package by IBM 1983). This paper discusses how in certain cases the method can be extended to include the Master Production Schedule decision level forming a hierarchical input/output control system. As far as the form of production organization and the relevant variability of input and output work-flow are concerned it considers the following two different types of production which are thought to be of particular interest for the application of IOC methods: (1) general job-shop production of customized products and (2) production of standard products in sequenced operations.