Economic and Performance Analysis of Dual-Bay Vertical Lift Modules

Poster

Economic and Performance Analysis of Dual-bay Vertical Lift Modules

Warehouse picking is one of the most time and cost consuming activities in a warehouse, often requiring the presence of human operators, who travel within the aisles to retrieve the items needed by the customers. Several studies demonstrate that the travelling activity can represent even the 50% of the total picking time, with a subsequent creation of a separate storage and picking area for small objects. In the last years, new solutions for order picking systems have been developed, especially for small items. One of these solutions requires Vertical Lift Modules (VLMs), storage columns with extractable trays. In this paper, the employ of dual-bay VLMs, compared to a carton racks warehouse, has been analysed from an economic point of view. Some mathematical formulations have been developed, to estimate the total annual cost and the respective convenience limits of both systems, according to their productivity. Moreover, some useful guidelines for practitioners are derived

Multi-objective task allocation for collaborative robot systems with an Industry 5.0 human-centered perspective

The migration from Industry 4.0 to Industry 5.0 is becoming more relevant nowadays, with a consequent increase in interest in the operators' wellness in their working environment. In modern industry, there are different activities that require the flexibility of human operators in performing different tasks, while some others can be performed by collaborative robots (cobots), which promote a fair division of the tasks among the resources in industrial applications. Initially, these robots were used to increase productivity, in particular in assembly systems; currently, new goals have been introduced, such as reducing operator's fatigue, so that he/she can be more effective in the tasks that require his/her flexibility. For this purpose, a model that aims to realize a multi-objective optimization for task allocation is here proposed. It includes makespan minimization, but also the operator's energy expenditure and average mental workload reduction. The first objective is to reach the required high productivity standards, while the latter is to realize a human-centered workplace, as required by the Industry 5.0 paradigms. A method for average mental workload evaluation in the entire assembly process and a new constraint, related to resources' idleness, are here suggested, together with the evaluation of the methodology in a real case study. The results show that it is possible to combine all these elements finding a procedure to define the optimal task allocation that improves the performance of the systems, both for efficiency and for workers' well-being

preventing ergonomic risks with integrated planning on assembly line balancing and parts feeding

In this paper, we advise to perform assembly line balancing simultaneously with decision-making on parts feeding. Such integrated planning may open additional potential to reduce labour costs. Additional planning flexibility gained with the integrated planning may be used to mitigate ergonomic risks at workplaces. We formulate the integrated assembly line balancing and parts feeding planning problem, propose a mixed-integer model and compare integrated planning to a common hierarchical planning approach in a detailed case study on the assembly of a self-priming pump. Our case study illustrates that workplaces with high ergonomic risks may emerge even in productions that involve handling parts and workpieces of low weights and avoid static and awkward postures. We also show that the proposed integrated planning approach may eliminate excessive ergonomic risks and improve productivity indicators simultaneously

the response latency in global production and logistics a trade off between robotization and globalization of a chain

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INNOVATIVE METHODS AND MODELS FOR INTEGRATED WAREHOUSE PICKING SYSTEMS DESIGN

The warehouse picking area is the zone within a warehouse in which the shipping units for the customers are created, through the pick of the required products from the various stocking locations. When there is the presence of human operators, walking or travelling within the warehouse aisles to retrieve the items needed by the customers and reported on their picking lists, the picking system is called manual picker-to-parts picking system. Although several automated solutions have been developed so far, these kind of systems are still the most widespread ones, since the presence of human pickers warrants great flexibility as well as relatively low investment costs. Due to its peculiarities, warehouse picking is often referred to as the most cost- and time-consuming activity in a warehouse, accounting for about 50% of all operating costs. Furthermore, this aspect becomes even more critical considering the recent trends that characterise the current logistics context, in which the goods are expected to be delivered always in a faster way, in small quantities and with a high service level. This need of fulfilling the customer orders in a very small time window translates into a consequent deep necessity for practitioners and warehouse managers of improving the performances of the picking activities. In such a background, the present dissertation aims at proposing a set of innovative methods and procedures useful for warehouse manual picker-to-parts picking systems design. In particular, it is based on the main assumption that the improvement of the picking performances can be achieved by reducing the time needed to process the picking orders. Following the research by Tompkins et al. (2010), reporting which time components are the most impacting ones during a picking tour, this thesis proposes some actions and, subsequently, some methods leading to travel time reduction, product search time reduction, item physical pick time reduction and, finally, overall time reduction. The thesis is structured into 4 main parts: (1) Analysis of the current logistics context to define the operating conditions of the warehouse picking systems (2) Proposal of actions for travel time reduction, arriving to the development of integrated procedures for the reduction of the distances travelled by the operators (3) Proposal of actions for search and pick time reduction, defining the need of paperless picking adoption (4) Proposal of actions for overall time reduction, through the study of the ergonomic impact of the picking activities Part of the research has been carried out as a visiting Ph.D. Student at the Department of Law and Economics of the TUD - Technische Universität Darmstadt in Darmstadt, Germany, in collaboration with prof. Christoph Glock and Dr. Eric Grosse. The research work presented in this thesis has also led to several scientific contributions, both in international conferences and international journals.L’area di picking (o prelievo frazionato) all’interno di un magazzino è la zona in cui vengono create le unità di spedizione dei clienti, attraverso il prelievo dei prodotti richiesti dalle varie locazioni di stoccaggio. Se in questa area vi è la presenza di operatori umani, che camminano o viaggiano all’interno dei corridoi del magazzino per recuperare gli oggetti richiesti dai clienti, e riportati sulle loro liste di prelievo, il sistema di picking viene chiamato sistema di picking manuale operatore-verso-materiale. Nonostante nel tempo siano state inventate e sviluppate numerose soluzioni automatizzate, questo tipo di sistema è ancora il più diffuso, dato che la presenza degli operatori garantisce una grande flessibilità così come dei costi di investimento relativamente contenuti. A causa delle sue peculiarità, l’attività di picking di magazzino viene spesso indicata come l’attività che richiede maggiori sforzi in termini di costo e tempo, costituendo da sola il 50% di tutti i costi operativi di un magazzino. Inoltre, questo aspetto diventa ancora più critico se si considerano le ultime tendenze che caratterizzano l’attuale contesto logistico, nel quale i clienti richiedono che la merce venga consegnata rapidamente, in piccole quantità e con un elevato livello di servizio. Questa necessità di soddisfare gli ordini cliente in una finestra temporale molto ristretta si traduce in una conseguente necessità per i professionisti e i manager logistici di un miglioramento delle prestazioni delle attività di picking. All’interno di questo contesto, la presente trattazione si pone come obiettivo quello di proporre un insieme di metodi e procedure innovativi utili alla progettazione di sistemi di picking manuale operatore-verso-materiale. In particolare, questa si basa sull’assunzione principale secondo la quale il miglioramento delle prestazioni di picking può essere raggiunto riducendo il tempo necessario all’evasione degli ordini di prelievo. Partendo dalla ricerca proposta da Tompkins et al. (2010), in cui vengono riportate quali sono le maggiori componenti di tempo che caratterizzano una missione di picking, questa tesi propone alcune azioni e, successivamente, alcuni metodi che portano alla riduzione del tempo di percorrenza, del tempo di ricerca del prodotto da prelevare, del tempo di prelievo fisico del prodotto e, infine, del tempo complessivo. La tesi si compone di 4 parti principali: (1) Analisi dell’attuale contesto logistico al fine di definire le condizioni di funzionamento dei sistemi di picking di magazzino (2) Proposta di azioni per la riduzione dei tempi di percorrenza degli operatori, giungendo allo sviluppo di procedure integrate per la riduzione delle distanze percorse dagli operatori (3) Proposta di azioni per la riduzione del tempo di ricerca del codice da prelevare e del tempo di prelievo, definendo la necessità di adozione di sistemi di paperless picking (4) Proposta di azioni per la riduzione del tempo globale, attraverso lo studio dell’impatto ergonomico delle attività di picking Parte di tale ricerca è stata svolta presso il Dipartimento di Diritto ed Economia del TUD - Technische Universität Darmstadt, a Darmstadt, Germania, in collaborazione con il prof. Christoph Glock e il Dr. Eric Grosse. Il lavoro di ricerca presentato in questa tesi ha portato anche alla formalizzazione di diversi contributi scientifici, sia in conferenze internazionali che in riviste scientifiche, sempre a carattere internazionale

INNOVATIVE METHODS AND MODELS FOR INTEGRATED WAREHOUSE PICKING SYSTEMS DESIGN

The warehouse picking area is the zone within a warehouse in which the shipping units for the customers are created, through the pick of the required products from the various stocking locations. When there is the presence of human operators, walking or travelling within the warehouse aisles to retrieve the items needed by the customers and reported on their picking lists, the picking system is called manual picker-to-parts picking system. Although several automated solutions have been developed so far, these kind of systems are still the most widespread ones, since the presence of human pickers warrants great flexibility as well as relatively low investment costs. Due to its peculiarities, warehouse picking is often referred to as the most cost- and time-consuming activity in a warehouse, accounting for about 50% of all operating costs. Furthermore, this aspect becomes even more critical considering the recent trends that characterise the current logistics context, in which the goods are expected to be delivered always in a faster way, in small quantities and with a high service level. This need of fulfilling the customer orders in a very small time window translates into a consequent deep necessity for practitioners and warehouse managers of improving the performances of the picking activities. In such a background, the present dissertation aims at proposing a set of innovative methods and procedures useful for warehouse manual picker-to-parts picking systems design. In particular, it is based on the main assumption that the improvement of the picking performances can be achieved by reducing the time needed to process the picking orders. Following the research by Tompkins et al. (2010), reporting which time components are the most impacting ones during a picking tour, this thesis proposes some actions and, subsequently, some methods leading to travel time reduction, product search time reduction, item physical pick time reduction and, finally, overall time reduction. The thesis is structured into 4 main parts: (1) Analysis of the current logistics context to define the operating conditions of the warehouse picking systems (2) Proposal of actions for travel time reduction, arriving to the development of integrated procedures for the reduction of the distances travelled by the operators (3) Proposal of actions for search and pick time reduction, defining the need of paperless picking adoption (4) Proposal of actions for overall time reduction, through the study of the ergonomic impact of the picking activities Part of the research has been carried out as a visiting Ph.D. Student at the Department of Law and Economics of the TUD - Technische Universität Darmstadt in Darmstadt, Germany, in collaboration with prof. Christoph Glock and Dr. Eric Grosse. The research work presented in this thesis has also led to several scientific contributions, both in international conferences and international journals.L’area di picking (o prelievo frazionato) all’interno di un magazzino è la zona in cui vengono create le unità di spedizione dei clienti, attraverso il prelievo dei prodotti richiesti dalle varie locazioni di stoccaggio. Se in questa area vi è la presenza di operatori umani, che camminano o viaggiano all’interno dei corridoi del magazzino per recuperare gli oggetti richiesti dai clienti, e riportati sulle loro liste di prelievo, il sistema di picking viene chiamato sistema di picking manuale operatore-verso-materiale. Nonostante nel tempo siano state inventate e sviluppate numerose soluzioni automatizzate, questo tipo di sistema è ancora il più diffuso, dato che la presenza degli operatori garantisce una grande flessibilità così come dei costi di investimento relativamente contenuti. A causa delle sue peculiarità, l’attività di picking di magazzino viene spesso indicata come l’attività che richiede maggiori sforzi in termini di costo e tempo, costituendo da sola il 50% di tutti i costi operativi di un magazzino. Inoltre, questo aspetto diventa ancora più critico se si considerano le ultime tendenze che caratterizzano l’attuale contesto logistico, nel quale i clienti richiedono che la merce venga consegnata rapidamente, in piccole quantità e con un elevato livello di servizio. Questa necessità di soddisfare gli ordini cliente in una finestra temporale molto ristretta si traduce in una conseguente necessità per i professionisti e i manager logistici di un miglioramento delle prestazioni delle attività di picking. All’interno di questo contesto, la presente trattazione si pone come obiettivo quello di proporre un insieme di metodi e procedure innovativi utili alla progettazione di sistemi di picking manuale operatore-verso-materiale. In particolare, questa si basa sull’assunzione principale secondo la quale il miglioramento delle prestazioni di picking può essere raggiunto riducendo il tempo necessario all’evasione degli ordini di prelievo. Partendo dalla ricerca proposta da Tompkins et al. (2010), in cui vengono riportate quali sono le maggiori componenti di tempo che caratterizzano una missione di picking, questa tesi propone alcune azioni e, successivamente, alcuni metodi che portano alla riduzione del tempo di percorrenza, del tempo di ricerca del prodotto da prelevare, del tempo di prelievo fisico del prodotto e, infine, del tempo complessivo. La tesi si compone di 4 parti principali: (1) Analisi dell’attuale contesto logistico al fine di definire le condizioni di funzionamento dei sistemi di picking di magazzino (2) Proposta di azioni per la riduzione dei tempi di percorrenza degli operatori, giungendo allo sviluppo di procedure integrate per la riduzione delle distanze percorse dagli operatori (3) Proposta di azioni per la riduzione del tempo di ricerca del codice da prelevare e del tempo di prelievo, definendo la necessità di adozione di sistemi di paperless picking (4) Proposta di azioni per la riduzione del tempo globale, attraverso lo studio dell’impatto ergonomico delle attività di picking Parte di tale ricerca è stata svolta presso il Dipartimento di Diritto ed Economia del TUD - Technische Universität Darmstadt, a Darmstadt, Germania, in collaborazione con il prof. Christoph Glock e il Dr. Eric Grosse. Il lavoro di ricerca presentato in questa tesi ha portato anche alla formalizzazione di diversi contributi scientifici, sia in conferenze internazionali che in riviste scientifiche, sempre a carattere internazionale

Modelling time efficiency of cobot-supported kit preparation

Kitting – meaning to supply assembly with components in pre-sorted kits – is widely seen as beneficial for assembly quality and efficiency when there is a multitude of component variants. However, the process by which kits are prepared – the kit preparation – is labour intensive, and kit errors are problematic at assembly processes. The use of robotics to support kit preparation has received some attention by researchers, but literature is lacking with respect to how collaborative robots – cobots – can support kit preparation activities. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. To address the purpose, the paper presents a mathematical model for estimation of the cycle time associated with cobot-supported kit preparation. The model is applied in a numerical example with experimental data from laboratory experiments, and cobot-supported kit preparation is compared with manual kit preparation. The findings suggest that cobot-supported kit preparation is beneficial with diverse kits and smaller components quantities per SKU (Stock Keeping Unit) and provides less variability of the outcome, when compared to manual kit preparation. The paper reveals several insights about cobot-supported kit preparation that can be valuable for both academics and practitioners. The model developed can be used by practitioners to assess the potential of cobots to support kit-batch preparation in association with assembly, spare parts, repair and maintenance, or business to business industry

Throughput models for a dual-bay VLM order picking system under different configurations

Purpose Vertical lift module (VLM) is a parts-to-picker system for order picking of small products, which are stored into two columns of trays served by a lifting crane. A dual-bay VLM order picking (dual-bay VLM-OP) system is a particular solution where the operator works in parallel with the crane, allowing higher throughput performance. The purpose of this paper is to define models for different operating configurations able to improve the total throughput of the dual-bay VLM-OP system. Design/methodology/approach Analytical models are developed to estimate the throughput of a dual-bay VLM-OP. A deep evaluation has been carried out, considering different storage assignment policies and the sequencing retrieval of trays. Findings A more accurate estimation of the throughput is demonstrated, compared to the application of previous models. Some use guidelines for practitioners and academics are derived from the analysis based on real data. Originality/value Differing from previous contributions, these models include the acceleration/deceleration of the crane and the probability of storage and retrieve of each single tray. This permits to apply these models to different storage assignment policies and to suggest when these policies can be profitably applied. They can also model the sequencing retrieval of trays