A lean assessment tool based on systems dynamics

Lean manufacturing is synonymous with a set of practices used in the identification and elimination of waste related with the manufacturing system, and focusing on what creates value for the customer. Lean assessment tools enable an overall audit of the performance of lean practices, and so are able to identify lean improvements. The interactions between lean practices and their improvements are often latent and need to be investigated: a systems approach can be used to disclose these hidden interactions. In this article, system dynamics is used as a lean assessment tool to assess and improve lean performance for a print packaging manufacturing system

Takt Time Grouping: A Method to Implement Kanban-Flow Manufacturing in an Unbalanced Process with Moving Constraints

One-piece flow and kanban/pull methods have been used to reduce WIP and speed flowtime in manufacturing flow processes; however, these methods have limitations. For example, one-piece flow does not work well when there are relatively large set-up times required between different components. One-piece flow also requires operations to be well-balanced. Unfortunately, these conditions often do not exist. The Theory of Constraints drum-buffer-rope (DBR) method is designed for unbalanced processes, and it has been shown to be effective for products with large operation time variation. However, DBR does not generally optimize flowtime and cannot handle a process with moving constraints (bottlenecks). Recognizing that there are manufacturing applications that have these limitations, we have developed a method called Takt Time Grouping (TTG) for implementing kanban-flow manufacturing when one-piece flow or DBR do not perform well. TTG combines one-piece flow, transfer-batch sizing and DBR concepts through the use of a grouping algorithm. Using a discrete event simulation model, the application of TTG, one-piece flow, DBR and a dynamic version of DBR, that moves the time-buffer and drum when it is known that constraints move (DynDBR), was investigated under varying conditions and production processes. Generalized findings of TTG’s advantages over competing methods are presented

A Simulation Analysis of Constrained Rate and Line Assembly Processes

Simulation presents a way to analyze the performance of a system with zone capacity constraints, operator constraints, and precedence constraints in an assembly line using takt analysis. A small-scale model of an aircraft assembly line is built in Simio and precedence constraints are modified in independent simulations. The primary performance metric is traveled work, for which a definition is given. A method of calculating traveled work is presented, as well as an interpretation that states the effect on throughput. These results show that, ceteris paribus, traveled work increases flowtime, which decreases throughput. Modifications to the system are suggested that can reduce traveled work

Manufacturing enhancement through reduction of cycle time using time-study statistical techniques in automotive industry

Within the complex and competitive automotive manufacturing industry, manufacturing Cycle Time (CT) remains one of the Key Performance Indicators (KPIs). Its reduction is of strategic importance as it contributes to time-to-market shortening, faster bottleneck detection, achieving throughput targets and improving production-resource scheduling. This paper presents a case study on CT analysis for early stage identification of the bottleneck stations and the processes in a manual assembly line that is responsible for increased manufacturing CT. The case study is conducted on an automotive seat manufacturing plant in the UK. For detailed CT analysis, CT of each station is recorded. Results of the case study shows that bottlenecks identification at an early stage can significantly enhance the overall performance of the production line

Novel availability and performance ratio for internal transportation and manufacturing processes in job shop company

Purpose: Purpose of this study includes the quantification of the impact of transportation efficiency onto the workstations the transportation serves in term of throughput and total lead time elapsed by product. Besides, it aims to synchronize the capacity available among workstations throughout a production line by studying the upper limit of throughput could be afforded by each workstation as well as their connection with each other. This study is also done on the purpose of promoting fulfillment of customer demand at shorter delivery time and minimal equipment utilization. Investigation on implementation of Overall Equipment Effectiveness (OEE) in an aerospace part-manufacturing company is studied to track out the potential opportunities to be improved. Design/methodology/approach: Site observation is conducted on all the five manufacturing workstations in the aforementioned aerospace part manufacturing company. Time data of both automated processes and manual processes are collected and they are used to construct simulation model. From that, various scenarios of transportation efficiency are simulated in Experiment 1. In addition, Experiment 2 is also set to examine the maximum capacity of each workstation. All of these are to highlight the relationship between workstation and processes and to verify the condition of imbalanced capacity among workstations in the company. In short, this has necessitated the integration of workstation and transportation activities within the company. These are followed by proposal of measures to quantify the wastes identified. Findings: The paper finds that implementation of OEE alone does not consider the reasonability of customer demand fulfillment. The results show that both transportation efficiency and imbalanced capacity throughout production system are not emphasized by OEE implementation in the case company. Therefore, responsibility of all workstations and transportation process in delivering demand on time are quantified. Transportation process which serves as the connectors of manufacturing processes is quantified and monitored by proposed Transportation Measure (TM) whereas workstations are measured using novel availability and performance ratio. Research limitations/implications: Future research should be conducted to examine the impact of other station within a company such as warehouse and logistic department to the performance of equipment and materials in manufacturing workstation. Besides, the material availability as well as the skills or performance of man power could be further incorporated into the measures to consider all the entities involved in manufacturing processes. Practical implications: The proposed availability and performance ratio for both transportation and manufacturing processes, which are related to each other, help in promoting better effectiveness of production system in terms of production amount and lead time. Besides, reasonable utilization equipment and minimal consumption of material are incorporated in the measures to promote Lean way in fulfilling customer demand. The effectiveness of entire production line is examined as a unity with joint responsibility under varying transportation efficiency and cycle time of each workstation. Both measures could be implemented together to optimize the production system and quantify the hidden wastes which are neglected in the OEE implementation. Originality/value: The novel availability and performance ratio are proposed to consider customer demand, historical equipment utilization and Takt time of each workstation to examine the possibility and reasonability of demand fulfillment. This prevents both over-processing and overproduction issues which are invisible in OEE. Furthermore, delay propagation throughout production system and interrelationship between processes are quantified under transportation measure. Other novelty of the paper is that it monitors the waiting time and lead time spent in each workstation at the same time considering utilization of workstation. The proposed Transportation Measure (TM) aims to reduce the queue length and waiting time at destination workstation at minimal utilization of forklift. It also promotes less capacity investment in transportation and prioritizes its scheduling according to urgency of destination workstation.Peer Reviewe

Development of the framework for a lean, energy efficient, and environmentally friendly port: umm qasr port as a Case Study

The research focus is to examine rigorously how the implementation of Lean within the Umm Qasr Port improves the operation processes and to explore the Lean impact on environment improvement and energy efficiency management. In this research, the ROPMEE model has been developed by the researcher to evaluate the service quality in the cargo delivery process in the Port of Umm Qasr as it covers all the functional and non-functional areas in the cargo delivery process compared to other quality dimensions. The findings confirm that the process quality dimension is the most influential factor in service quality in the Port of Umm Qasr. The reasons for the poor performance of current practices adopted by the port are the use of traditional ways of information flow and a decision-making process that requires more time and steps within the whole process. The lack of smooth process flow is a potential cause of bottlenecks within port operation that create serious problems not only for the customer but also for the port itself. In this research, a visual representation is created of how the current value stream map for different port processes has been established on the identification and elimination of non- value-added activity or “waste” involved in delivering services in Umm Qasr port for customers. A VSM tool was applied to visually map the cargo handling flow, ship entrance, ship maneuvering and cargo clearance to display the current and future states of processes in a way that highlights opportunities for improvement. Based on the defined and classified waste according to the seven deadly wastes of Lean, this research suggests a future value stream map for port processes. The impact of the identified wastes has been quantified in terms of cost, carbon dioxide emissions working time efficiency, and energy consumption cost. This research is the first attempt to develop a Lean port model for improving port processes, as there have been no previous studies aimed at providing a holistic framework for improving port performance, which can be used by other ports. Implementing the Lean approach requires a gradual shift in work culture by involving all port employees and customers in the continuous improvement process and changing the service delivery from a push to pull system

Model Development of a Virtual Learning Environment to Enhance Lean Education

AbstractModern day industry is becoming leaner by the day. This demands engineers with an in-depth understanding of lean philosophies. Current methods for teaching lean include hands-on projects and simulation. However, simulation games available in the market lack simplicity, ability to store the results, and modeling power. The goal of this research is to develop a virtual simulation platform which would enable students to perform various experiments by applying lean concepts. The design addresses these deficiencies through the use of VE-Suite, a virtual engineering software. The design includes user-friendly dialogue boxes, graphical models of machines, performance display gauges, and an editable layout. The platform uses laws of operations management such as Little's law, economic order quantity (EOQ) models, and cycle time. These laws enable students to implement various lean concepts such as pull system, just-in-time (JIT), single piece flow, single minute exchange of dies (SMED), kaizen, kanban, U-layout, by modifying the process parameters such as process times, setup times, layout, number, and placement of machines. The simulation begins with a traditional push type mass production line and the students improve the line by implementing lean techniques. Thus, students experience the advantages of lean real time while facing the real life problems encountered in implementing it

Towards a unified descriptive framework for industrial objective declaration and performance measurement

International audienceExpressing the performance of industrial companies is an important feature for their continuous improvement. As the performance concept refers to the objective one, our idea is to relate the performance expression mechanism to that of the objective declaration. We propose a variable tree framework to describe the break-down of objectives and the expression of the performances, highlighting the multicriteria aspect of both the performance and the objectives. Moreover, the temporal aspects of the objective declarations are emphasised, leading to the introduction of both the objective and the performance temporal trajectories. Such trajectories take into account the whole of the temporal horizon that is associated with the achievement of the objective. The link between the provided trees and trajectories is established through the elementary objective notion which corresponds to the leaves of the trees. A conventional recursive depth-first search algorithm is applied to the variable tree for the computation of the corresponding performances, at any considered milestone of the temporal horizon. Finally, the overall throughput time of the hydraulic cylinders manufacturing line of the Bosch Rexroth Company is considered to illustrate the proposed ideas

Extending the production dice game.

The production dice game is a powerful learning exercise focusing on the impact of variability and dependency on throughput and work-in-process inventory of flow lines. In this paper we will extend the basic dice game along the following lines. First, we allow that the operations take place concurrently as opposed to the more traditional way of playing the game sequentially. Second, we allow both starvation and blocking of the line. Third, we consider balanced lines with work stations characterized by different degrees of variability. Fourth, we use different sets of dice in order to represent a wide range of coefficients of variation of the production line. The game can be played manually in a classroom setting, but it is also modelled as an easy-to-use simulation tool.

Process Improvement at Source International

The objective of this Major Qualifying Project was to help Source International to optimize their manufacturing process for the Modular product line while reducing costs, non-value added time, and employee motion within their work area. The methods used to accomplish this included axiomatic design matrix, Lean Methodologies comprised of value stream map, spaghetti diagram, DMAIC, 5S methodology, 7 Wastes, and Arena® Simulation. The team’s recommendations included implementing these Lean Methodologies tools in order to improve the Modular product line. In conclusion, the application of Lean Analytic tools would yield substantial savings in time and money, and increasing efficiency of the manufacturing process that Source International uses