A case study on improving logistics by using vending machines for supplying personal protection items in mining operations

Abstract

Personal protection elements (PPE) such as safety glasses, work clothing,  ear plugs, are fast-moving, low cost items in most industrial settings for which warehousing and dispatching is required. In some cases, such warehousing is centralized and therefore personnel must deliver in large amounts such elements to workers, thus demanding man hours, space, and transportation for miners and other workers to centralized facilities.  Automating the delivery by using vending machine technology located at critical locations is a natural way to deal with the problem.  However, the number of machines, locations, replenishment times and quantities, communication links, backup modes, and supplier modes (internal or outsourced) will define different design configurations given the number of alternatives that can arise during conceptual design of the network.  In this paper we present a mathematical model for optimizing the logistics costs involving this kind of decisions: such as inventory costs, stock out costs, transportation, and equipment operational costs.  An example and numerical analysis is provided.