Simulation Analysis of Mixed Bulk and Rack Warehouse Systems

With the growth of the supply chain and increased customer demand, warehouse operation has become very important. One of the critical functions of warehouse operation is to have a warehouse layout such that the day-to-day operations enable on-time delivery. Poor warehouse design can lead to ineffective warehouse space utilization and incur the cost associated with inefficient operations. The purpose of this study is to develop an analysis tool that enables companies to identify the appropriate mix of bulk and rack storage locations to utilize warehouse space effectively. A simulation-based methodology is used to determine the optimal mix of racks and bulk lanes for a warehouse layout considering inventory quantities and turnover rates. Evaluation parameters include the number of racks and storage locations, the number of bulk lanes and lane depth, and the velocity mapping of products based on demand. The experimental results demonstrate the trade-offs of key performance metrics for various system configurations

Integrated Models and Tools for Design and Management of Global Supply Chain

In modern and global supply chain, the increasing trend toward product variety, level of service, short delivery delay and response time to consumers, highlight the importance to set and configure smooth and efficient logistic processes and operations. In order to comply such purposes the supply chain management (SCM) theory entails a wide set of models, algorithms, procedure, tools and best practices for the design, the management and control of articulated supply chain networks and logistics nodes. The purpose of this Ph.D. dissertation is going in detail on the principle aspects and concerns of supply chain network and warehousing systems, by proposing and illustrating useful methods, procedures and support-decision tools for the design and management of real instance applications, such those currently face by enterprises. In particular, after a comprehensive literature review of the principal warehousing issues and entities, the manuscript focuses on design top-down procedure for both less-than-unit-load OPS and unit-load storage systems. For both, decision-support software platforms are illustrated as useful tools to address the optimization of the warehousing performances and efficiency metrics. The development of such interfaces enables to test the effectiveness of the proposed hierarchical top-down procedure with huge real case studies, taken by industry applications. Whether the large part of the manuscript deals with micro concerns of warehousing nodes, also macro issues and aspects related to the planning, design, and management of the whole supply chain are enquired and discussed. The integration of macro criticalities, such as the design of the supply chain infrastructure and the placement of the logistic nodes, with micro concerns, such the design of warehousing nodes and the management of material handling, is addressed through the definition of integrated models and procedures, involving the overall supply chain and the whole product life cycle. A new integrated perspective should be applied in study and planning of global supply chains. Each aspect of the reality influences the others. Each product consumed by a customer tells a story, made by activities, transformations, handling, processes, traveling around the world. Each step of this story accounts costs, time, resources exploitation, labor, waste, pollution. The economical and environmental sustainability of the modern global supply chain is the challenge to face

Robotized Warehouse Systems: Developments and Research Opportunities

Robotized handling systems are increasingly applied in distribution centers. They require little space, provide flexibility in managing varying demand requirements, and are able to work 24/7. This makes them particularly fit for e-commerce operations. This paper reviews new categories of robotized handling systems, such as the shuttle-based storage and retrieval systems, shuttle-based compact storage systems, and robotic mobile fulfillment systems. For each system, we categorize the literature in three groups: system analysis, design optimization, and operations planning and control. Our focus is to identify the research issue and OR modeling methodology adopted to analyze the problem. We find that many new robotic systems and applications have hardly been studied in academic literature, despite their increasing use in practice. Due to unique system features (such as autonomous control, networked and dynamic operation), new models and methods are needed to address the design and operational control challenges for such systems, in particular, for the integration of subsystems. Integrated robotized warehouse systems will form the next category of warehouses. All vital warehouse design, planning and control logic such as methods to design layout, storage and order picking system selection, storage slotting, order batching, picker routing, and picker to order assignment will have to be revisited for new robotized warehouses

Warehousing: a comparative methodology approach

The aim of this study is to find ways to increase an agile flow of materials in a warehouse while comparing different methodologies. In order to achieve this goal, an analysis of the current status of a warehouse of raw material and packaging is carried out and some situations that lack improvements are highlighted. Afterwards enhancements are suggested in several dimensions: the analysis of the capacity, the allocation method and the layout. To analyse the current situation, two different tools are created in Excel, all from the beginning, taking into consideration the company’s point of view and the new one, proposed by the author. Regarding the capacity, a volume approach is suggested so as to understand the warehouse capacity. Thus, a change in the storage assignment policy is proposed which results in a different layout. Evidence leads to the conclusion that with the proposed methodology it is possible to see a warehouse with a more balanced occupation, a decrease in costs, in material damages, and in the travelling distance and time (29,96 km/year, approximately 32,52 hours). An increase in the warehouse capacity (9,77%) and in terms of safety can also be identified, leading to the conclusion that the suggested methodology could be implemented.O objetivo da presente dissertação é encontrar formas de fomentar um fluxo ágil de materiais num armazém, comparando diferentes metodologias. Para atingir este objetivo, é feita uma análise do estado atual de um armazém de matérias primas e produtos de embalagem. Após investigar e compreender o funcionamento do mesmo, algumas situações que carecem de melhoria são destacadas. Posteriormente, são sugeridos alguns aprimoramentos em várias dimensões: na análise da capacidade, no método de alocação e no layout. Para examinar a situação atual, são criadas duas ferramentas distintas em Excel, tendo em consideração o ponto de vista da empresa e o da nova proposta apresentada pela autora. Relativamente à capacidade, é sugerida uma abordagem que tem em consideração o volume por forma a identificar a verdadeira capacidade do armazém. Assim, é apresentada a possibilidade de uma mudança na política de armazenamento, que resulta num layout diferente. Os resultados levam à conclusão de que, com a metodologia da autora, é possível observar um armazém com ocupação mais balanceada, uma diminuição nos custos, nos danos dos materiais, na distância e no tempo de deslocação (29,96 km/ano, aproximadamente 32,52 horas). Também se consegue identificar um aumento de 9,77% na capacidade do armazém e um acréscimo de segurança, levando à conclusão de que a metodologia sugerida poderia ser implementada

Internal report cluster 1: Urban freight innovations and solutions for sustainable deliveries (1/4)

Technical report about sustainable urban freight solutions, part 1 of

Analytical and economic methodology for storage of large heavyweight equipment in industrial processes

Numerous studies concerning warehouse-design methodologies have been performed focused on the storage of products on pallets or of intermediate size and/or moderate weight loads. These studies, however, do not provide with optimal results for industries that work with equipment or objects of uncommon sizes and shapes and with large weights, which are difficult to move and involve high costs and complex operational actions, affecting to the production processes and interfering with the logistic processes or the supply-chain of a company. This study proposes an analytical methodology using economic and technical qualitative criteria that can be applied specifically to large and heavy equipment warehouses. Both quantitative aspects, such as availability and cost of space, and also qualitative considerations, such as flexibility requirements, impact on manufacturing process and risks associated, are evaluated. To determine an optimum implementation solution, several decision-making methods, such as Electra I & II and Analytic Hierarchy Process are employed with due consideration of multiple criteria. The results obtained are modulated and reinforced using a SWOT (strengths-weaknesses, opportunities- threats) and a Risk analysis to verify this single ultimate solution. The said process led to the establishment of a decision-making methodology suitable for any organization possessing large-scale storage systems

Design and Control of Efficient Order Picking Processes

Binnen een logistieke keten dienen producten fysiek te worden verplaatst van de ene locatie naar de andere, van producenten naar eindgebruikers. Tijdens dit proces worden producten gewoonlijk opgeslagen op bepaalde plaatsen (magazijnen) voor een bepaalde periode. Orderverzameling – het ophalen van producten uit de opslaglocatie in het magazijn naar aanleiding van een specifieke klantorder – is het meest kritieke magazijnproces. Het is een arbeidsintensieve operatie in handmatig bestuurde systemen, en een kapitaalintensieve operatie in geautomatiseerde systemen. Een niet optimaal functionerend orderverzamelingsproces kan leiden tot onbevredigende service en hoge operationele kosten voor het magazijn, en dientengevolge voor de hele keten. Om efficiënt te kunnen functioneren dient het orderverzamelingsproces robuust te zijn ontworpen en optimaal te worden bestuurd. Dit proefschrift heeft als doel analytische modellen te ontwerpen die het ontwerp en de besturing van efficiënte orderverzamelingsprocessen ondersteunen. Verschillende methoden worden voorgesteld voor het schatten van de route langs de locaties van de te verzamelen producten, het bepalen van de optimale grenzen van zones in het magazijn die bestemd zijn voor opslag, de indeling van het magazijn, het aantal producten die tegelijk (in één ronde) worden verzameld (de batch size) en het aantal zones in het magazijn die worden ingericht voor het verzamelen en gereedmaken van orders. De methoden worden getest middels simulatie experimenten en worden inzichtelijk gemaakt met behulp van rekenexperimenten.Tho Le-Duc was born in 1974 in Quang Ninh, Vietnam. He received a Bachelor degree in Navigation Science from the Vietnam Maritime University in 1996 and a Postgraduate Diploma in Industrial Engineering from the Asian Institute of Technology Bangkok Thailand (AIT) in 1998. Thanks to the financial support from the Belgian Development and Co-operations, he obtained his master degree in Industrial Management from the Catholic University of Leuven in 2000. Since May 2001, he started as a Ph.D. candidate (AIO) at the RSM Erasmus University (formerly Rotterdam School of Management/Faculteit Bedrijfskunde), the Erasmus University Rotterdam. For about more than four years, he performed research on order picking in warehouses. As the results, Tho Le-Duc has been presented his research at several conferences in the fields of operations research, material handling, logistics and supply chain management in both Europe and North America. His research papers have been published or accepted for publication in several refereed conference proceedings, scientific books and international journals.Within a logistics chain, products need to be physically moved from one location to another, from manufacturers to end users. During this process, commonly products are buffered or stored at certain places (warehouses) for a certain period of time. Order picking - the process of retrieving products from storage (or buffer area) in response to a specific customer request - is the most critical warehouse process. It is a labour intensive operation in manual systems and a capital intensive operation in automated systems. Order picking underperformance may lead to unsatisfactory service and high operational cost for the warehouse, and consequently for the whole chain. In order to operate efficiently, the order picking process needs to be designed and optimally controlled. Thesis Design and Control of Efficient Order Picking Processes aims at providing analytical models to support the design and control of efficient order picking processes. Various methods for estimating picking tour length, determining the optimal storage zone boundaries, layout, picking batch size and number of pick zones are presented. The methods are tested by simulation experiments and illustrated by numerical examples

Material flow design in a warehouse - The case of S:t Eriks

The proposed evaluation process concluded with providing some suggestions for the stockyard that helps S:t Eriks Staffanstorp to work in a more time efficient way, to achieve a better customer service related to shipping times. The solution is divided into two different ideas: storing according the ABC analysis assigning the areas close to the shipping area the A products, and the second one is focus on the implementation of a pre-order area next to the shipping positions

Optimizing the Performance of Robotic Mobile Fulfillment Systems

A robotic mobile fulfillment system is a novel type of automated part-to-picker material handling system. In this type of system, robots transport mobile shelves, called pods, containing items between the storage area and the workstations. It is well suited to e-commerce, due to its modularity and it's ability to adapt to changing orders patterns. Robots can nearly instantaneously switch between inbound and outbound tasks, pods can be continually repositioned to allow for automatic sorting of the inventory, pods can contain many different types of items, and unloaded robots can drive underneath pods, allowing them to use completely different routes than loaded robots. This thesis studies the performance of robotic mobile fulfillment systems by solving decision problems related to warehouse design, inventory and resource allocation, and real-time operations. For warehouse design, a new queueing network is developed that incorporates realistic robot movement, storage zones, and multi-line orders. For inventory allocation, we develop a new type of queueing network, the cross-class matching multi-class semi-open queueing network, which can be applied to other systems as well. Resource (re)allocation is modeled by combining queueing networks with Markov decision processes while including time-varying demand. This model compares benchmark policies from practice wit