Simulation as a Tool for Optimizing Logistics Flows to Increase Assembly Line Productivity

This work focuses on internal logistics (IL), which is defined as the flows of materials inside the same business or the same plant. We centre on the IL activities of a car-assembling company. The main objective is to propose simulation models’ concepts that evaluate assembling lines under the IL point of view. We present a real case study based on SEAT S.A., a company in the Volkswagen group. We developed a Discrete-Event Simulation model through the Plant Simulation software. The company set the main Key Performance Indicators, which are related to the logistics flows’ performance (LFP) and an assembly lines’ aisles utilisation. The results expose which aisles are overused, the disturbs among the logistics flows, and the LFP, regarding the total of backorders, the trips duration, and the routes’ length in terms of distances and time. Moreover, we offer aset of best practices for further applications in that field.

The loading and unloading process are activity of unloading goods from ships with cranes and then being brought and arranged in temporary warehouses. PT Prima Termina Petikemas is a subsidiary of Pelindo which is engaged in shipping container loading and unloading services. For customer satisfaction, one of the indicators of the company is the truck round time (TRT) which is 33 minutes. Currently, the external truck round time (TRT) for delivery is 43.62 minutes with waiting time by 16.32 minutes and truck round time (TRT) receiving is 37.72 minutes with waiting time by 9.75 minutes. The discrete event simulation method aims to evaluate the determination of effective alternative container yard locations to anticipate truck round time (TRT). For all improvement scenarios carried out, the selected scenario for delivery using 4 blocks and 6 units of Automated Rubber Gantry Tyred (1 unit reach stacker) and the percentage of each block load is 20%. This can reduce the truck round time (TRT) 27.37 minutes with the waiting time is to 8.93 minutes. For receiving activity using 5 blocks and 6 units of Automated Rubber Gantry Tyred (ARTG) and the percentage of each block load is 20%. The waiting time become 9.92 minutes and this reduces the truck round time (TRT) by 33.67 minutes.

This theoretical article explores logistic activity. It reviews, evaluates and compares definitions, explications and interpretations of logistic activity. The author offers and discusses four cases of interpretation of logistic activity, highlighting and focusing on logistic activity in a broad sense.The author discusses features of logistic activity, its links with logistics, supply chain and marketing. The article presents an overview of a series of terms related to logistic activity and logistics. An evaluation of a logistic approach as yet another candidate to be considered as a general scientific approach is presented.The author has performed an analysis of elements of logistic activity and its components and presents a classification of the components of logistic activity, namely phenomena and actions.Much attention is paid to the interaction between subjects of logistic activities, peculiarities of such interaction at the current stage of human activity, highlighting and discussing institutions performing control operations.The author discusses in detail the material flows in logistics and logistic activities and analyses the impact of logistic activities on these flows. In the article, a definition of the material flow in logistic activity, the properties of such flow are analysed, and several classifications of material flows are proposed. The performed flow analysis has shown that it is appropriate to distinguish and analyse not only material flows, but also the resources of logistic activities.The article contains a comprehensive analysis of the concept of logistic activity, which is the main goal of this publication.

PurposeThe purpose of this paper is to develop a computer simulation model to evaluate the bowl phenomenon and the allocation at the end of the line of stations with either greater mean operation times or higher variability of operation times.Design/methodology/approachThe model was developed on the basis of a realistic case problem and applied to a six‐station assembly line. The evaluation criteria were the: minimization of the total elapsed time; maximization of the average percentage of working time; and minimization of the average time in the system.FindingsThe performance of an assembly line with independently normally distributed operation times could be improved by applying the bowl phenomenon. The allocation of large operation mean times to stations located near the end of the line did not produce improved results. Instead a more balanced allocation proved to be more significantly effective. On the other hand, the assignment of larger variability of operation times to the stations near the end of the line improved the performance of the assembly line.Originality/valueThe investigation contributed to the computer simulation approach to solving assembly line problems that dealt with the impact of normally distributed operation times on the bowl phenomenon and assembly lines with increasing mean operation times and higher variability of operation times at the end of the line of stations.

Assembly logistics involves the material flow that is closely related to the assembly process of products. The optimisation of assembly logistics is of great significance for shortening the delivery period whilst improving the operating efficiency of the assembly lines. However, due to the uncertainties caused by the stochastic arrival sequence of customer orders in a build-to-order environment, it becomes difficult to find the optimal solution to assembly lines with pure mathematical methods. The objective of this paper is to optimise assembly process from the logistics simulation perspective. This paper begins with the analysis of logistics activities that occur at the assembly lines of a specific auto plant. Using the methodology of business process reengineering, several assembly lines are reengineered according to the assembly processes, product models and time of delivery. Secondly, a logistics simulation model of the assembly lines is established and major control variables of the model are specified. Taking an actual customer order for example, the paper finally presents the optimal operation parameters of the assembly lines based on the results of logistics simulation with the help of an interactive 3-dimensional animation and visualised analytical tool. The simulation results indicate that the operating efficiency of the optimised automobile assembly lines has been improved greatly; the occupation time of finished products warehouse and the time of delivery are shortened dramatically.

Financial and environmental sustainability in manufacturing of crepe rubber in terms of material flow analysis, material flow cost accounting and life cycle assessment

Queueing-model based analysis of assembly lines with finite buffers and general service times

The aim of this research is to reveal the overall money flows and physical flows of the livestock and feed production supply chain in Thailand in order to analyze the resource use and cost and assess material use efficiency of the whole supply chain. Another aim is to evaluate the options to improve and evaluate trade-off between economic and environmental performance. This research conducted material and monetary flow modeling using material flow analysis (MFA) and input output analysis (IOA). Data collected from the Thai Input-Output Tables 2005 were employed to develop the monetary flow model. Direct and indirect resource consumption (energy, water, and land use) and turnover along the supply chain were assessed using environmentally extended input-output analysis model (EEIOA). Scenario analysis with improvement options was applied to the model to evaluate the effectiveness of the improvement options. One third of energy and water consumption were from the animal farm itself. The rest were from feed production and upstream raw material production. Land use in the system was mainly from maize and paddy field. Feed conversion ratio improvement should play an important role in the strategy for resource efficiency and reduce environmental impact in the whole supply chain. Energy intensity reduction, the best option in overall energy reduction, is the policy that the government is pushing to be implemented in all sectors, and it can also easily be applied along with the other options. Therefore, it should be applied with the other options for improvement. The results from monetary flow and physical material flow can visually show the holistic view of the Thai livestock production supply chain quantitatively and allow the stakeholders to understand the economic structure of the supply chain system. This can enable the decision makers to analyze the interrelation effect and impact of changing one sector demand or changing resource efficiency to impact other sectors in the system.

Growing production volumes and high-quality requirements are some of the main challenges faced by manufacturing industries today. End of line rejections and rework contribute towards increasing the component costs, which in turn affects the customer pricing or company profits. The workaround created due to rework increases the complexity of flow and contributes to the hidden factory. This paper elaborates a step-by-step approach using a case study to develop a quality filter mapping for an engine assembly line which eliminates end-of-line rejections and rework. A pareto analysis reveals the vital few defects that are occurring along the assembly line. The root causes of these defects are identified using a cause-and-effect diagram and are mapped along material flow in the assembling plant. The quality filter map can be used to integrate quality control into the process flow and thereby prevent the flow of defectives in assembly and manufacturing lines.

This paper presents a compelling argument for optimizing the logistics flow of wiring harnesses within the automotive industry to address the rising production demands of vehicle manufacturers. It introduces an innovative assembly line structure specifically designed to boost efficiency and enhance responsiveness to client needs. Drawing from data gathered from an actual assembly line dedicated to producing engine harnesses for K9K engines, this study offers a practical and impactful foundation for its proposed optimization strategies. The new assembly structure effectively merges the benefits of a dynamic line—which emphasizes efficient space utilization and flexibility—with the strengths of a rotary line, particularly in light of the increasing complexity associated with harness production. The paper features a mathematical model that calculates cycle times for workstations within this new system architecture, optimizing the entire production process. Moreover, it illustrates how advanced modeling, simulation, and optimization techniques using WITNESS Horizon Version Release 25.0 can identify necessary adjustments for achieving optimal assembly line balance. Additionally, this research addresses pressing environmental concerns by proposing a robust recycling strategy for the scrap produced during wiring harness manufacturing. By advocating for sustainable practices and responsible waste management, the study highlights the importance of minimizing the ecological footprint of the automotive manufacturing process. In summary, this research provides essential insights and practical solutions for optimizing wiring harness logistics flow in the automotive industry. By implementing these strategies, manufacturers can significantly enhance their production capacity, improve operational efficiency, and maintain competitiveness in an ever-evolving market landscape.

This article delves into the significance of logistics process optimization in the construction industry and its direct impact on productivity. Construction companies face unique challenges in managing the flow of materials, equipment, and personnel, making streamlined logistics crucial for efficient project delivery. By examining key strategies and approaches to logistics optimization, this article aims to provide insights into how construction companies can increase productivity and maximize project outcomes. The construction industry is a complex and dynamic sector that relies heavily on effective logistics processes to ensure the smooth flow of materials, equipment, and personnel. In an era where efficiency and productivity are key drivers of success, construction companies are increasingly focusing on optimizing their logistics operations. By streamlining and enhancing these processes, companies can significantly improve productivity, reduce costs, and ultimately deliver projects more efficiently. This article explores the importance of logistics optimization in construction and provides insights into key strategies for achieving enhanced productivity, because optimizing logistics processes in construction is instrumental in increasing productivity and achieving successful project outcomes. By focusing on effective planning, technology adoption, lean principles, collaboration, and modular construction, companies can streamline operations, reduce costs, and enhance resource utilization. The article emphasizes that logistics optimization is an ongoing journey that necessitates adaptability and awareness of industry trends. By prioritizing logistics optimization, construction firms can position themselves for success, deliver projects on time and within budget and ultimately gain a competitive advantage in the market.

PurposeThe purpose of this paper is to ascertain and expose considerations related to the division of assembly lines into segments, and to develop a framework for assessing the impact of line segmentation. In particular, the paper aims to investigate the decision regarding the number of stations in each segment, and its impact on costs, throughput, and span of control.Design/methodology/approachThe paper analyzes the literature, identifies the main considerations related to assembly line segmentation, and develops a mathematical model that reflects important factors related to the impact of segment length on the throughput and costs. The paper derives several important bounds on the number of stations (length) of a line's segment, which should be incorporated in the final design of the line sections.FindingsA trade‐off was found between the revenue (and throughput) and the buffer spaces located between each pair of sections of an assembly line. The higher the product price, the shorter the segments are. On the other hand, when buffer costs are higher, the line segments are longer (fewer sections and buffers are used). Interestingly, except of stoppages, the other two dominant factors in the segmentation decision are: absenteeism, and span of control. Using these factors, various upper bounds were found on the number of stations per section (which determine the total number of sections). The tightest upper bound is the active one, and this ensures line sections with a small number of stations.Practical implicationsThe model provides a framework of considerations to help designers of assembly lines and production lines determine the appropriate division of the line into sections and zones, and the best allocation of stations to sections. In addition, finding effective upper bounds for the number of stations in a line section establishes the practicality of exact methods for designing and balancing each section.Originality/valueThis is the first paper to offer a quantitative treatment of the various factors affecting assembly line segmentation. By finding the upper bound on the number of station per section, the paper establishes the practicality of exact methods for designing and balancing each section separately. Moreover, it provides a sound basis for future research related to design of assembly and production lines, and management of sequential processes.

Background: To remain relevant in the customer-oriented market, hospitals must pay attention to the quality of services and meet customers' expectations from admission to discharge stage. For an outpatient customer, pharmacy is the last unit visited before discharge. It is likely to influence patient satisfaction and reflect the quality of hospital's service. However, at certain hospitals, the waiting time is long. Resources need to be deployed strategically to reduce queue time. Objective: This research aims to arrange the number of staff (pharmacists and workers) in each station in the pharmacy outpatient service to minimise the queue time.Methods: A discrete simulation method is used to observe the waiting time spent at the pharmacy. The simulation run is valid and effective to test the scenario. Results: It is recommended to add more personnel for the non-compounding medicine and packaging to reduce the waiting time by 22.41%Conclusion: By adding personnel to non-compounding and packaging stations, the system performance could be improved. Cost-effectiveness analysis should be done to corroborate the finding. Keywords: Discrete Event Simulation, Hospital, Outpatient Service, Pharmacy Unit, System AnalysisBackground: To remain relevant in the customer-oriented market, hospitals must pay attention to the quality of services and meet customers' expectations from admission to discharge stage. For an outpatient customer, pharmacy is the last unit visited before discharge. It is likely to influence patient satisfaction and reflect the quality of hospital's service. However, at certain hospitals, the waiting time is long. Resources need to be deployed strategically to reduce queue time. Objective: This research aims to arrange the number of staff (pharmacists and workers) in each station in the pharmacy outpatient service to minimise the queue time.Methods: A discrete simulation method is used to observe the waiting time spent at the pharmacy. The simulation run is valid and effective to test the scenario. Results: It is recommended to add more personnel for the non-compounding medicine and packaging to reduce the waiting time by 22.41%Conclusion: By adding personnel to non-compounding and packaging stations, the system performance could be improved. Cost-effectiveness analysis should be done to corroborate the finding. Keywords:Discrete Event Simulation, Hospital, Outpatient Service, Pharmacy Unit, System Analysis

A Knowledge Based Design Methodology for manufacturing assembly lines

Complexity is an important quantification of uncertain operation in assembly lines and the key source of invisible uncertainty problems in smart manufacturing. The purpose of this paper is to propose a complexity measurement approach to assess the complexity of assembly lines integrating humans, machines and configurations. First, the complexity models of the three states of the operation related to humans and machines are built based on information entropy and the operation time model. Then, an operational complexity model is built at the station level; it is constructed with a single station, parallel stations and sublines based on Kolmogorov entropy. The model quantitatively describes the cumulative complexity along with the material flow. Furthermore, the complexity model of the overall system is given, and the Lempel–Ziv algorithm is applied to measure the complexity flow along with the stations. The complexity equilibrium index is derived to quantify the balancing degree among the stations. The model incorporates uncertain operation into system modeling to quantify the influence of uncertainties on the state of the assembly line. An engine assembly line is used to validate that the approach can measure the complexity from operation to station to system.