To meet the needs and demands of the costumer, accurate information about how much is available in stock is necessary. When the information in the system does not match the physical inventory, inventory inaccuracy occurs. Inventory inaccuracy is common among companies and may contribute to increased labor cost, excess inventory, production disruptions, waste of time, late deliveries, poor service and lost customers. The purpose of this study is to identify contributing factors to inventory inaccuracy for business with outdoor storage. The study also aims to investigate how efficiency factors can reduce the inventory inaccuracy for business with outdoor storage. A case study was conducted to answer the purpose. A company in the steel industry was chosen to examine inventory inaccuracy on business with outdoor storage. During the case study a series of interviews was conducted with employees and managers. Together with information from observations and documents the information from the interviews was compiled into flowcharts. Inventory inaccuracy affects companies with in many ways and leads to inefficiency. Incorrect inventory leads to unnecessary work and costs and can also contribute to a reduced efficiency for business with outdoor storage. Inventory inaccuracy may be reduced with continuous inventory checks, simplified processes, more automation, enhanced information and communication. Improved routines can also help reduce inventory inaccuracy. To increase efficiency, the staff must be seen as an important resource.

Contrairement à un système d'identification plus traditionnel tel que le code à barres, la nouvelle technologie RFID (Radio Frequency IDentification) utilise des ondes radio fréquence pour transmettre des données entre une étiquette et un lecteur pour pouvoir identifier, localiser ou suivre une entité dans une chaîne d'approvisionnement. Cette propriété lui procure certains avantages (facilité d'accès à l'information, suivi continu, amélioration de l'exactitude des données, détection du vol et de la contrefaçon, etc..) par rapport à d'autres systèmes d'identification et de capture de données. Nous partons du constat que l'utilisation de cette nouvelle technologie permettra aux acteurs de la chaîne logistique de pouvoir partager une information de meilleure qualité, plus exhaustive et fiable concernant le flux physique et le suivi de la localisation produits. Or, l'hypothèse implicite considérée dans la plupart des modèles classiques de gestion de stock est que l'on a une connaissance parfaite du flux entrant et sortant. L'objectif de recherche sera d'intégrer dans ces modèles des dégradations venant fausser le flux nominal et d'en analyser les conséquences (en termes de coût additionnel). Un accent fort sera mis sur le développement de solutions combinant efficacité et simplicité. L'accent sera mis aussi sur le mode de partage du coût de cette technologie entre plusieurs acteurs de la chaîne logistique : serait-il mieux de partager les bénéfices de cette technologie dans un environnement de coordination ou dans un environnement de compétitivité entre acteurs? Les résultas de cette thèse porte sur l'élaboration de modèles théoriques -de type gestion de stock – concernant la production, la distribution et l'approvisionnement dans une chaîne logistique et faisant intervenir et le coût et les gains potentiels de cette nouvelle technologie d'identification automatique.

This thesis is focused on a simulation modelling approach to address the inventory inaccuracy problems in a warehouse operation. The main motivation which led to this research was a desire to investigate the inventory inaccuracy issues that have been highlighted by a logistics company. Previous and current research into inventory inaccuracy issues is largely related to the development of RFID technology as a possible solution to inventory problems. Since the inventory inaccuracy related to RFID technology is focused on the overall measurement of inventory management and retail business, there are differences between this existing research and the research presented in this thesis which is focused on issues of inventory inaccuracy in a warehouse operation. In this thesis, warehouse operation is studied as a detailed sequence of processes that are involved in the flow of items physically in parallel with related information being stored in the computer system. In these processes there are many places where errors can occur in counting or recording details of inventory, or in physically moving, storing or picking items incorrectly. These details of a warehouse operation are used to develop a conceptual model of inventory inaccuracy in warehouse operations. The study also found that typically a product needs to be considered differently at different stages of its progress through a warehouse (and therefore within different sections of the conceptual model). This is because initially batches of a product are likely to be delivered from a supplier, therefore if errors occur soon after the product is delivered to the warehouse, the error might involve the whole batch (for example the batch may be misplaced and put in an incorrect storage location), or the error might involve just part of the batch (for example poor transportation by forklift truck may damage the packaging carton and some of the items within the carton). When the product is stored ready for meeting customer orders, it needs to be considered as individual items (and errors can occur in counting of individual items or individual items may be misplaced or stolen). Finally, when a customer order is received, the product will be picked and grouped to meet the requirements of the order (for example, one order may require 10 of the product whilst another order may require 20 of the product). Errors might again occur to the whole group or to just part of the group. (Continued ...)