Optimizing Retrieving Performance of an Automated Warehouse for Unconventional Stock Keeping Units

In recent years, the diffusion of automated warehouses in different industrial sectors has fostered the design of more complex automated storages and handling solutions. These circumstances, from a technological point of view, have led to the development of automated warehouses that are very different from the classic pallet Automated Storage and Retrieval Systems (AS/RS), both in terms of design and operating logic. A context in which these solutions have spread is the steel sector. Warehouses with innovative layouts and operating logics have been designed to move metal bundles of different sizes, weights and quality levels, instead of standard, interchangeable stock keeping units. Moreover, picking is often not allowed in these warehouses, due to the configuration of the loading units. In this work we propose a meta-heuristic algorithm based on the Simulated Annealing (SA) procedure, which aims to optimize performance during the retrieving phase of an automated warehouse for metal bundles. The algorithm translates the customers’ requests, expressed in terms of item code, quality and weight into a list of jobs. The goal is to optimize the retrieving performance, measured in missions per hour, minimizing the deviations in quality and weight between customer request and the material retrieved. For the validation, a simulation model of an existing warehouse has been created and the performance of the algorithm tested on the simulation model has been compared with the current performance of the warehouse

Estimating travel times in dual shuttle AS/RSs.: A revised approach

Automated Storage and Retrieval Systems (AS/RSs) effectively support warehouse operations in order to increase production and logistics efficiency. Literature about travel time computation in multi-shuttle AS/RSs still needs to be enhanced since most of the existing contributions rely on the same formulation, namely the Meller and Mungwattana’s equation. Based on well-established theoretical assumptions and on a simulation model, the present work puts forward a revised version of the Meller and Mungwattana’s formula for dual shuttle systems. In particular, the constant factor multiplying the travel between time is replaced by a coefficient depending on the rack configuration and on the input and output points of the storage system. The new equation is tested against widely applied models for AS/RS travel time calculation and proves to result in shorter times than the original Meller and Mungwattana’s equation. A linear regression analysis is completed in order to find a numerical formulation of the proposed coefficient. Taking into account some key physical characteristics of a warehouse while estimating travel times allows improving the design and management of storage areas. Future research will focus on deepening multi-shuttle travel time calculation by addressing crane acceleration and deceleration, different rack and crane configurations, as well as class-based storage

Order-picking workstations for automated warehouses

The FALCON (Flexible Automated Logistic CONcept) project aims at the development of a new generation of warehouses and distribution centers with a maximum degree of automation. As part of the FALCON project, this dissertation addresses the design and analysis of (automated) workstations in warehouses with an end-of-aisle order-picking system (OPS). Methods are proposed for architecting, quantifying performance, and controlling such a system. Four main topics are discussed in this dissertation. First, a modular architecture for an end-of-aisle OPS with remotely located workstations is presented. This architecture is structured into areas and operational layers. A hierarchical decentralized control structure is applied. A case of an industrial-scale distribution center is presented to demonstrate the applicability of the proposed architecture for performance analysis using the process algebra-based simulation language $\chi$ (Chi). Additionally, it is demonstrated how the architecture allows straightforward modification of the systems configurations, design parameters, and control heuristics. Second, a method to quantify the operational performance of order-picking workstations has been developed. The method is based on an aggregate modeling representation of the workstation using the EPT (Effective Process Time) concept. A workstation is considered in which a human picker is present to process one customer order at a time while products for multiple orders arrive simultaneously at the workstation. The EPT parameters are calculated from arrival and departure times of products using a sample path equation. Two model variants have been developed, namely for workstations with FCFS (First-Come-First-Serve) and for workstations with non-FCFS processing of products and orders. Both models have been validated using data from a real, operating workstation. The results show that the proposed aggregate modeling methodology gives good accuracy in predicting product and order flow time distributions. Third, the dissertation studies the design and control of an automated, remotely located order-picking workstation that is capable of processing multiple orders simultaneously. Products for multiple orders typically arrive out-of-sequence at the workstation as they are retrieved from dispersed locations in the storage area. The design problem concerns the structuring of product/order buffer lanes and the development of a mechanism that overcomes out-of-sequence arrivals of products. The control problem concerns the picking sequence at the workstation, as throughput deteriorates when a poor picking sequence is applied. An efficient control policy has been developed. Its performance is compared to a number of other picking policies including nearest-to-the-head, nearest neighbor, and dynamic programming. Subsequently, the resulting throughput and queue length distribution are evaluated under different settings. Insights for design considerations of such a system are summarized. Finally, the dissertation reflects on the findings from the proposed methods and uses them to come up with comprehensive design principles of end-of-aisle OPS with remotely located workstations. The various issues influencing the performance of such a system are highlighted. Moreover, the contribution of each proposed method with regards to these issues is delineated

Materials lead time reduction in a semiconductor equipment manufacturing plant : process flow planning

Thesis: M. Eng. in Manufacturing, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 90-92).Process flow at a semiconductor tool manufacturer was studied with the goal of reducing production order lead time to 8 hours. Current material flow systems were studied and interviews with the involved personnel were conducted. Additionally, data was extracted and analyzed from the company's SAP Extended Warehouse Management database to analyze the past performance of the material flow group. Three areas for improvement were analyzed and recommendations were made regarding each area. First, it is recommended that an additional truck driver is hired and that a final delivery is made after the last warehouse worked stops working. This will reduce the time that parts wait for the truck to pick them up and eliminate any parts that wait overnight. Second, warehouse employees should start work earlier in the morning to complete sales picks; this will allow the rest of the workers to work on production orders in the morning, immediately after they are placed. Third, the tracking scans to put parts into and out of the consolidation areas should be removed. This will allow workers to preform the picking and consolidation steps faster. These recommendations are to be combined with other material flow improvements. It was determined that the goal of 8 hours lead time was unrealistic. However, calculations suggest that lead time will be reduced to 16 hours.by Ryan Surveski.M. Eng. in Manufacturin

The design principles and success factors for the operation of cross dock facilities in grocery and retail supply chains

Dissertation (PhD)--Stellenbosch, 2004.ENGLISH ABSTRACT: The dissertation reflects the research done on the design principles and success factors for the operation of cross dock facilities in grocery and retail supply chains. The cross dock is a particular facility in the supply chain where goods are received from suppliers, sorted without storage of the goods, and then efficiently moved to downstream customers. Cross docks are not a new operation. However, the use in high volume grocery and retail operational capabilities is poorly understood and is not uniquely defined. The problem is that cross docks are often seen as extensions of warehouses. The same personnel, systems and processes are applied and the efficiency potential of the cross dock is not achieved. Warehouses are orientated towards storing the full range of product and allowing the pick to be done from this storage buffer to provide any or all of these products to a customer. Cross docks will only handle products that are used in larger quantities and that are sent to most, if not all, the customers. The cross dock is therefore distinct and very different from the traditional warehouse. The published research tends to focus on the technical aspects of the cross dock layout. This research is primarily in the scheduling of the trucks into the yard of the facility; the allocation of trucks to specific doors of the facility; and the allocation of doors to receiving and despatch functions within the facility. Very little information or research reflects the design principles and success factors for the cross dock and its supply chain. The only classification of the cross dock in the literature is whether the barcode is added to the item before or after receipt at the cross dock. For this research work a literature survey was conducted and five major operations were reviewed, in South Africa and the USA. The research empirically drew logical conclusions, which were tested in the operations and found to be correct. This allowed the design principles and success factors to be determined for a successful cross dock. The research extends the knowledge of the cross dock operation and design: - • A new classification for the feasible types of cross docks in the supply chain was developed. Three factors are shown to be of primary importance: - o Where in the supply chain the identification of specific items for a customer is done; o Where the sort is done for the items to be delivered to a customer; and o Whether the supplier is providing one product or multiple products to the sort. From these three factors, eight potential classifications could be defined. However, only three practical types of cross dock can be determined from these eight alternatives. These are named in this research as Cross Dock Managed Load (CML); Joint Managed Load (JML); and the Supplier Managed Load (SML). The cross dock is far more effective than the warehouse when the total work (excluding inventory) is considered. The earlier in the supply chain the product is identified for the use of the entire downstream supply chain, the more effective will be the total supply chain. Thus the greatest supply chain effectiveness possible is with the SML, then the JML and finally the CML. • The operation of a cross dock is very similar to a continuous manufacturing process. There is no buffer of stock to decouple the inbound and outbound processes, and the operation takes place in a restricted area. However, in the retail chain, the workload alters with different orders and different days. Daily load differences vary by as much as 90%. This results in vastly different workloads and variations of throughput. This is similar to a batch operation with highly variable workloads between batches. The literature recommends the use of Just in Time (JIT) practice for cross docks. This is inappropriate as its primary requirements are continuous full volume operation and continuous small improvements to achieve a balanced operation. The most appropriate method of process improvement is the Theory of Constraints (TO C) and not JlT. • The management must have a detailed, disciplined approach. This implies standardised methods of operation, and a high degree of training. Equally there is the requirement for a special type of personnel to operate the cross dock. These operating personnel must be able to operate with precision (i.e. very low error rates) and be able to maintain this capability for continuous periods. • The systems required for a successful operation must include the capabilities of Yard Management, WMS for cross docking, Order Management with Advanced Shipping Notice (ASN) capability and Track and Trace across the supply chain. The items need to be identified by a barcode. The information required on the barcode will be determined by. the information systems capability of the least advanced service provider in the supply chain. If this service provider can receive and transmit all the data required for the supply chain from and to the other members, then the barcode need only be an identification number of the specific item. The data pertaining to the items is then passed from system to system in the supply chain. If data movement is not possible between all the parties in the entire supply chain, then the barcode must contain the information that will identify the item, the origin and the final delivery destination. If the items are delivered as part of a consignment, a further quantum of information is required to identify the total number of items in the consignment and the specific item within the consignment. • The research shows that the overall capability of the cross dock or its maximum capacity is the combination of the capability of the personnel and the cross dock design. Restrictions on either the personnel capability or the design of the cross dock, or both, severely reduces the effectiveness of the cross dock. • The previous research on the sequence of allocation of trucks to specific doors within the cross dock can be enhanced with a new sequencing method. The new method allocates the transport, in sequence of arrival, to the open door that either numrruses the walk distance in the facility; or maximises the completion of the consignments in order to minimise the area required to build the consignments; or a combination of both. The choice of these will be determined by the constraints imposed by the design of the building. This is an important extension as this ties the supply chain into the cross dock operation, rather than looking at the cross dock in isolation as has been done in this previous research. • The factors that influence the design of a cross dock as to its size, shape, number of doors, and the specifically required additional areas, is defined in detail. The principles of these factors and their inter-relationships and dependencies are used in a detailed design for a cross dock. The detailed design process is set out from data analysis through to the actual size calculations and layouts. Measurements of walk distance and sort movement are used to determine the most effective design. The design is shown to be considerably more effective than the older designs. This work has significantly extended the research on the design principles and success factors for implementation of cross docks in retail supply chains. The research derives a unique new classification for cross docks. An improvement is made to existing research on the allocation of the transport to particular doors in the cross dock. The operation, management and personnel are shown to require specific characteristics. The information systems required for effective cross docks is determined and defined. The identification of the individual items by barcode and the information required within the barcode depending on the information sophistication of the service providers in the supply chain is defined. A detail process to design a cross dock is evolved, with the full knowledge of the factors that must be considered and their interrelationships. Measurements to determine the effectiveness of the design are used to choose the most appropriate design. All these are then synthesised into a new design, which is far more effective than any of the other designs researched. The design process will produce a very effective cross dock as has been demonstrated with a new facility.AFRIKAANSE OPSOMMING: geen opsommin

Synchronizing the Retail Supply Chain

Dit proefschrift ontwerpt een retail supply chain, die beter en goedkoper is dan de gangbare. Dit wordt bereikt door de distributie te synchroniseren op de productie¬momenten. Goederen zouden direct uit productie al stroomafwaarts moeten bewegen, van fabrikant naar retailer, tegen lage kosten, in volle pallets en in volle auto’s en in hoeveel¬heden die groot genoeg zijn om de vraag tot het volgende productiemoment te dekken. Door de formules van de "Krantenverkoper" en die van de economische ordergrootte (EOQ) aan te passen aan een multi-echelon divergerend distributienetwerk, kan ook theoretisch worden bewezen dat het stroomafwaarts positioneren van voorraden inderdaad optimaal is en dat de voorraden daardoor zullen dalen. De huidige magazijnen van de leveranciers kunnen worden gereduceerd tot overslagpunten, waar goederen van de verschillende fabrieken van een leverancier worden samengebracht om rijden met vollere vrachtwagens mogelijk maken. Kleinere hoeveelheden kunnen leveranciers beter afleveren bij het dichtstbijzijnde distributiecentrum van een retailer, waarna de retailer zelf het deel met bestemming elders verder vervoert. Tenslotte kan de winkelbevoorrading worden aangepast aan de schapruimte, waardoor de werkwijze in de distributiecentra kan worden gerationaliseerd.Piet van der Vlist (1947) was born in Ouderkerk aan den IJssel. He received his high-school diploma from the Marnix Gymnasium in Rotterdam. Also in Rotterdam he graduated as Electronics Engineer at the University of Applied Sciences. He obtained a Master of Science in Electronics at the Delft University of Technology and one in Management Sciences at the University of Twente. He worked 15 years with the Dutch Ministry of Defense on the design and realization of the first generation digital communications systems. Then he joined Bakkenist Management Consultants and later Deloitte Consultancy, together for over 20 years. As consultant he was involved in numerous projects on Data exchange and Supply Chain redesign. Besides that, he was for 11 years (part-time) professor in ICT and Logistics at the Eindhoven University of Technology. Piet wrote and edited several books on data exchange and published numerous articles in business and scientific journals. A fairly good overview of his scientific career can be found in the "Liber Amicorum" that his friends wrote when he left Eindhoven University1. His current research interests lie in the design and management of retail supply chains, all the way from production down to the shelves. He found that the supply chain with the overall lowest costs requires synchronization of distribution to production and not the other way around as current practice seems to dictate. When he had to quit his jobs for health reasons, he finally found the opportunity to devote his time to research and extend the theory that supports Supply Chain Synchronization. He programmed built to purpose simulation models to get a better insight in the dynamics of synchronized supply chains. He joined both the Rotterdam Erasmus University to work with Professor Jo van Nunen and the Eindhoven University of Technology to work with Professor Ton de Kok. This PhD thesis is the result of that effort.This thesis is a design of a retail supply chain that is better and cheaper than the usual one. This is achieved by synchronizing distribution to production. Right from production goods should move downstream the supply chain at low cost in full pallets and in full truckloads, in quantities large enough to cover the needs till the next production run. By extending both the Newsvendor- and the EOQ-formulae to a multi-echelon divergent network, it can be proved that such forward positioning of inventory indeed is optimal and that overall supply chain inventories will drop. The suppliers’ warehouses become stockless cross docking points, where goods from the supplier’s various sourcing plants are brought together to consolidate them into full truckloads. Whenever suppliers deliver lower volumes, they better bring these goods to the nearest retailer’s facility; thereafter the retailer himself should move these goods onward to the proper destination within the retailer’s network. And finally shop replenishment should be rationalized based on shelf coverage, so as to enhance the retailer’s warehouse operations

Sequencing and Routing in a Large Warehouse with High Degree of Product Rotation

The paper deals with a sequencing and routing problem originated by a real-world application context. The problem consists in defining the best sequence of locations to visit within a warehouse for the storage and/or retrieval of a given set of items during a specified time horizon, where the storage/retrieval location of an item is given. Picking and put away of items are simultaneously addressed, by also considering some specific requirements given by the layout design and operating policies which are typical in the kind of warehouses under study. Specifically, the considered sequencing policy prescribes that storage locations must be replenished or emptied one at a time by following a specified order of precedence. Moreover, two fleet of vehicles are used to perform retrieving and storing operations, whose routing is restricted to disjoint areas of the warehouse. We model the problem as a constrained multicommodity flow problem on a space-time network, and we propose a Mixed-Integer Linear Programming formulation, whose primary goal is to minimize the time traveled by the vehicles during the time horizon. Since large-size realistic instances are hardly solvable within the time limit commonly imposed in the considered application context, a matheuristic approach based on a time horizon decomposition is proposed. Finally, we provide an extensive experimental analysis aiming at identifying suitable parameter settings for the proposed approach, and testing the matheuristic on particularly hard realistic scenarios. The computational experiments show the efficacy and the efficiency of the proposed approach

Una revisión al manejo y transporte de carga paletizada en el sector alimentos y su importancia en la reducción de costos logísticos

En el presente trabajo encontrara una minuciosa y muy estudiada revisión al manejo y traslado de las diferentes cargas existentes de manera paletizada en la industria alimenticia y la importancia que esta aporta a la reducción de costos y al logro de los diferentes objetivos trazados por las diferentes empresas. Este trabajo se ha enriquecido paso a paso con la inclusión de contenido bibliográfico que soporta las ideas, conocimiento y creencias respecto a los beneficios que tiene unitarizar cargas considerando su naturaleza, los costos dependiendo de la operación y de su tipo pueden reducirse considerablemente en tiempos de operación y conservar la integridad de los bienes. El problema planteado en este estudio está relacionado con la unitarización de carga en pallets, proceso en el que se apilan bienes sobre una plataforma para facilitar su manipulación, dando lugar a la optimización de las operaciones logísticas otorgando beneficios en tiempos y costos (Feng, S.2021, Pag 1-6). Existen formas adecuadas y económicas para el trasporte de mercancías a nivel nacional e internacional que por su naturaleza pueden ser transportadas de un lugar a otro de manera paletizada , sin embargo, el desconocimiento y falta de análisis del costo beneficio que esta actividad puede traer al proceso y en general a toda la red logística, ha hecho que no siempre se tenga en cuenta a la hora de establecer un mecanismo de carga y transporte de productos, cabe aclarar, que todo depende de la naturaleza de las cargas , porque existen algunas que no pueden ser trasportadas de esta manera , sin embargo, en general la gran mayoría se pueden unitarizar, y establecer mecanismos como el paletizado para la optimización de costos operativos y tiempos de alistamiento, cargues y descargues y demás actividades incluidas en la de manipulación de cargas que ayuden a minimizar los traslados y las averías por el trasporte hasta sus destinos finales. Por otra parte, el daño que pueden tener las mercancías durante el transporte, ocasionado por vibraciones y otros factores, puede ser irreversible y causar en esos casos no sólo pérdidas de producto y económicas si no, un nivel de servicio al cliente deficiente, más allá de recuperar el costo del producto mediante una póliza, finalmente todo bien y servicio tiene el propósito de satisfacer una necesidad, no llegar a ese fin es una gran pérdida para la organización, al mismo tiempo, la disposición final de éstos bienes, causa un alto perjuicio al medio ambiente. Muchas de las mercancías que llegan a los puertos lo hacen de manera paletizada, pero en estos desconsolidan las cargas y despachan a los diferentes clientes los productos a granel o arrume negro que llaman, lo que hace que el receptor tenga que asumir un costo adicional para el descargue, si se mantuviera la cadena de paletizado las operaciones finales serían más productivas y rentables para el cliente final. Dentro de la cadena logística, la manipulación de los productos se debe hacer bajo las mejores prácticas para conservar la integridad de los bienes, la elección del pallet correcto es fundamental para que el resultado de paletizar sea efectivo, existen varias clases de pallet de acuerdo con la necesidad y normatividad, de plástico, de madera, de aluminio, con tacos, dos entradas, tres entradas, entre otros. (Navascues R, 2001,) Los Pallets son excelentes aliados para los sistemas de información y de inventario, bien sea por código de barras, o por RFID o por cualquier otro tipo de tecnología, tener un tag o un código que permita llevar la trazabilidad del inventario, ayuda a conservar la integridad y confianza de la información (Navascues R, 2001,) ¿El envío de carga de manera paletiza es verdaderamente rentable para las operaciones logísticas dentro del proceso de transporte y traslado de mercancías? Con base en lo anteriormente expuesto, el objetivo general del presente estudio es documentar el proceso logístico de trasporte relacionado con el paletizado de mercancías en pro de determinar los diferentes beneficios para las operaciones logísticas de cargue y descargue. Por lo anterior, se plantean los siguientes objetivos específicos: - Analizar fuentes bibliográficas que contengan información sobre el manejo y transporte de carga paletizada y sus aportes en procesos logísticos. - Estudiar bases de datos relacionadas con paletizado y transporte de cargas con el fin de validar sus beneficios. - Demostrar que unitarizar carga es una decisión acertada en los procesos logísticos. En ese sentido, este estudio está justificado en los costos de los procesos logísticos en una operación que están directamente relacionados con el costo total del producto a comercializar y del que dependerá su precio de venta. En una economía tan vulnerable a causa de situaciones sociopolíticas y sumada una pandemia (COVID-19) que no dio tiempo de reaccionar, el poder adquisitivo de los consumidores disminuyó y ha dado pie a preferir los productos de menor precio, por consiguiente, es necesario buscar mecanismos para el traslado de mercancías que generen un valor agregado a la operación logística. La disminución de costos en todas las operaciones será la clave para mejorar los costeos de los diferentes productos, de tal manera que aumente su competitividad y buscar una preferencia en el mercado sin sacrificar la calidad del producto, el objetivo es disminuir de manera significativa todos los procesos en términos de dinero y tiempos de ejecución, también disminuir la carga laboral de los empleados involucrados en las diferentes actividades y contribuir al manejo adecuado de pesos por persona. Por lo anterior, esta investigación tiene como propósito brindar información clara sobre los beneficios en tiempos y movimientos, costos, integridad del producto, seguridad, entre otros, que otorga la unitarización de carga en pallets de acuerdo con la naturaleza y destino del producto. El trabajo está abordado de la siguiente manera: - Marco Conceptual y teórico: Respalda el proyecto con fuentes y referentes bibliográficos que comparten la misma teoría. - Metodología: da a conocer el conjunto de métodos de investigación y procedimientos para lograr los objetivos propuestos. - Resultados obtenidos: presenta los beneficios que se pretenden obtener al finalizar la elaboración y puesta en marcha del proyecto. - Discusión: expone de manera argumentativa los resultados esperados. - Bibliografía: Fuentes de consulta para el desarrollo del proyecto.In the present work you will find a meticulous and well-studied review of the handling and transfer of the different palletized loads in the food industry and the importance that this brings to the reduction of costs and the achievement of the different objectives set by the different companies. . This work has been enriched step by step with the inclusion of bibliographical content that supports the ideas, knowledge and beliefs regarding the benefits of unitizing loads considering their nature, the costs depending on the operation and its type can be considerably reduced in times of operation and preserve the integrity of the assets. The problem posed in this study is related to the unitization of cargo in pallets, a process in which goods are stacked on a platform to facilitate their handling, leading to the optimization of logistics operations, granting benefits in time and costs (Feng, S .2021, Pages 1-6). There are adequate and economical ways to transport merchandise at a national and international level that by their nature can be transported from one place to another in a palletized manner, however, ignorance and lack of cost-benefit analysis that this activity can bring to the process and in general to the entire logistics network, has meant that it is not always taken into account when establishing a mechanism for loading and transporting products, it should be clarified that everything depends on the nature of the loads, because there are some that do not can be transported in this way, however, in general the vast majority can be unitized, and establish mechanisms such as palletizing to optimize operating costs and set-up times, loading and unloading and other activities included in the handling of loads that help minimize transfers and breakdowns due to transportation to their final destinations. On the other hand, the damage that the goods may have during transport, caused by vibrations and other factors, may be irreversible and in these cases cause not only product and economic losses, but also a poor level of customer service, beyond to recover the cost of the product through a policy