WSC 2007 Final Abstracts

Manufacturing Applications Track

Monday 10:30:00 AM 12:00:00 PM
Productivity Improvement

Chair: Charles McLean (National Insitute of Standards and Technology)

Manufacturing Process Management Using a Flexible Modeling and Simulation Approach
Duilio Curcio, Francesco Longo, and Giovanni Mirabelli (University of Calabria)

The focus of this paper is a manufacturing system placed in Calabria (Italy) which produces high pressure hydraulic hoses. The objective is to implement a simulator to be used both for carrying out specific analysis devoted to increase system efficiency and for supporting the manufacturing process management (implementation of all the features required for using real time the simulator). After the modeling phase, the simulation model has been validated comparing simulation results with real system performances. In this paper the authors test tool potentials investigating system behavior under different scenarios obtained varying manufacturing departments configuration. The utilization degree of each manufacturing department and its daily production measure system performance.

Application of Design of Experiments on the Simulation of a Process in an Automotive Industry
Jose Arnaldo Barra Montevechi (Universidade Federal de Itajuba) and Alexandre Ferreira de Pinho, Fabiano Leal, and Fernando Augusto Silva Marins (Universidade Estadual Paulista)

The objective of this article is to apply the Design of experiments technique along with the Discrete Events Simulation technique in an automotive process. The benefits of the design of experiments in simulation include the possibility to improve the performance in the simulation process, avoiding trial and error to seek solutions. The methodology of the conjoint use of Design of Experiments and Computer Simulation is presented to assess the effects of the variables and its interactions involved in the process. In this paper, the efficacy of the use of process mapping and design of experiments on the phases of conception and analysis are confirmed.

Productivity Improvement in Appliance Manufacturing
Charles Harrell (Brigham Young University) and Bruce Gladwin (ProModel Corporation)

Simulation can be a useful tool when analyzing complex manufacturing systems to help sort through cause-and-effect relationships and gain a better understanding of what is actually causing a particular problem in the system. Once cause-and-effect relationships are identified, changes for improvement can be made more intelligently and then verified using simulation. This paper describes an application in which simulation was used to identify the bottleneck of a dishwasher tub manufacturing line. Engineers were then able to determine and verify a solution to the bottleneck which resulted in an annual cost savings of $275,000.

Monday 1:30:00 PM 3:00:00 PM
Lean Manufacturing

Chair: Charles Standridge (Grand Valley State University)

Using Multicriteria Modeling and Simulation to Achieve Lean Goals
Gerald W. Evans and Suraj M. Alexander (University of Louisville)

Lean principles require the identification of an ideal system state along with an associated policy to achieve that state. This paper discusses the use of multi-criteria models in conjunction with optimization procedures and simulation in order to identify an ideal system state and associ-ated policy. An illustration involving the determination of a replenishment policy for a distribution system is described.

"Pull" Replenishment Performance as a Function of Demand Rates and Setup Times Under Optimal Settings
Silvanus T. Enns (University of Calgary)

The problem of optimizing decision variables in a single-stage replenishment loop with capacity-constrained batch processing is examined. Simulation and response surface methods are used to model total inventory and delivery performance for a continuous-review reorder point system and a single-card Kanban system. Performance tradeoff curves based on optimal settings are created using non-linear optimization. The area under these curves is used as a single response for comparison. If tradeoff curves are experimentally replicated, main and interaction effects can also be statistically analyzed. Results show that under time-varying demand the reorder point system performs slightly better. Improvements in performance with setup time reduction are similar for both systems.

Measuring Manufacturing Throughput using Takt Time Analysis and Simulation
Jun Duanmu and Kevin Taaffe (Clemson University)

This paper is motivated by a case study performed at a company that manufactures two main types of customized products. In an effort to significantly increase their throughput capability, the company created a new production scheme based on takt time calculations. To achieve a smooth flow of production, they desired low Work In Process (WIP) inventory in order to make all components move simultaneously. However, the order of operations in key shared resources implies that a simple takt time calculation cannot provide enough information in determining achievable throughput. The process includes several parallel assembly lines that converge to common resources. In certain cases, these components are joined into one unit; in other cases the components split again for further customization. We attempt to improve throughput using a combination of takt time and simulation by understanding how each stage of the system interacts with other stages.

Monday 3:30:00 PM 5:00:00 PM
Automation and Material Handling

Chair: Jun Duanmu (Clemson University)

Modeling and Simulation of Hard Disk Dive Final Assembly Using a HDD Template
Ahad Ali (Lawrence Technological University) and Robert De-Souza (The Logistics Institute - Asia Pacific)

A HDD template is designed and developed for modeling and simulation for final assembly of hard disk drive (HDD) manufacturing using Arena. The designed HDD template is a high flexibility and good performance at an internal supply chain level and self-development and improves the system performance significantly. It is developed the intelligent based dynamic machine knowledge, which can capture dynamic based activities with fuzzy system. The study shows how modeling and simulation tools can be used and integrated to implement highly automated systems for industrial processes and deal with flexible products. In such context we designed and developed a prototype for the final assembly of hard disk drive with dynamic and static behavior.

Evaluation of Operational Policies in the Design Phase of Material Handling Networks
Ardavan Asef-Vaziri (California State University, Northridge)

We compare quality of solution and solution times of alternative operational dispatching policies that are integrated into the design phase of a material handling network for automated guided vehicle systems. Exact formulations describe the problem of optimal concurrent design of the unidirectional loop track layout along with the locations of the pickup and drop-off stations. The objective is to minimize the total loaded and empty vehicle trip distances, which is the main driver of the fleet size of the vehicles. A primary interest of our work is to illustrate the superiority of the shortest-trip-distance-first (STDF) over the first-come-first-served (FCFS) when integrated into the design phase. We also show that optimization under STDF in the design phase produces the best solution for first-encountered-first-served (FEFS) in the operation phase. The findings of the optimization models in the design phase are supported by the outcomes of the simulation model in the operation phase.

Simulation of Continuous Behavior Using Discrete Tools: Ore Conveyor Transport
Marcelo Moretti Fioroni and Luiz Augusto G. Franzese (Paragon Tecnologia), Jose Furia, Luciano de Toledo Perfetti, Donizeti Leonardo, and Nilson Laudelino da Silva (Companhia Siderurgica Paulista) and Caio Eduardo Zanin (Paragon Tecnologia)

The modeling of systems mixing discrete and continuous behavior is a challenge for model builders. Sometimes, the continuous part is important, but small near the complex decision making situation involved, and the requirement to learn new tools to model that continuous part is an obstacle that delays the project. This paper presents a technique to model continuous behavior using just discrete modeling elements. The technique was applied to model the conveyor network of a great steelmaking company in Brazil, and the results proved that this technique is valid.

Tuesday 8:30:00 AM 10:00:00 AM
Resource Planning

Chair: Gerald Evans (University of Louisville)

Establishing Man-machine Ratio Using Simulation
Hoay Hoon Ong (Intel Technology Sdn. Bhd.)

Effective use of machines and headcounts is essential in manufacturing for high return of investment from expensive resources in today competitive business environment. It is thus crucial to establish optimal man-machine ratio to gain high resource utilization and output. In this paper, we discuss the deficiency of traditional static methods and how simulation can be applied to overcome this deficiency in order to establish optimal man-machine ratio. In addition, we discuss using simulation to facilitate decision making on headcount movement from non-constraint tool to constraint tool to boost productivity of constraint tool, and ultimately increase overall factory output.

Paintshop Production Line Optimization Using Response Surface Methodology
Berna Dengiz (Baskent University) and Onder Belgin (National Productivity Center of Turkey)

This paper deals with the problem of determining the optimum number of workstations to be used in parallel and workers at some stations using simulation optimization approach in a paint shop line of an automotive factory in Ankara, Turkey. In the optimization stage of the study Response Surface Methodology (RSM) is used to find the optimum levels of considered factors. Simulation model and optimization stage integration is used both to analyse the performance of the current paint shop line and determine the optimum working conditions, respectively, with reduced cost, time and effort.

A Test Implementation of the Core Manufacturing Simulation Data Specification
Marcus Johansson (Chalmers University of Technology), Swee Leong (National Institute of Standards and Technology), Bjorn Johansson and Anders Skoogh (Chalmers University of Technology), Frank Riddick (National Institute of Standards and Technology), Par Klingstam (Volvo Car Corporation) and Y. Tina Lee and Guodong Shao (National Institute of Standards and Technology)

This paper describes an effort of testing the Core Manufacturing Simulation Data (CMSD) information model as a neutral data interface for a discrete event simulation model developed using Enterprise Dynamics. The implementation is based upon a model of a paint shop at a Volvo Car Corporation plant in Sweden. The model is built for a Swedish research project (FACTS), which focuses on the work procedure of developing new and modified production systems. FACTS has found standardized simulation data structures to be of high interest to achieve efficient data collection in conceptual stages of production development programs. For the CMSD-development team, implementations serve as an approach to validate the structures in CMSD and to gather requirements for future enhancements. CMSD was originally developed to support job shops, but the results of this implementation indicate a good possibility to extend CMSD to also support flow shops.

Tuesday 10:30:00 AM 12:00:00 PM
Warehousing and Distribution

Chair: S.T. Enns (University of Calgary)

Modeling and Simulation of Retrieving Process
Chin Yung Shih (University of Sao Paulo) and Jose Hamilton Chaves Gorgulho Junior (Federal University of Itajuba)

This paper presents a model of Parts Distribution Center (PDC), developed in Arena 5.0, which aims at providing information about the total time of the retrieving process as the system is working under unexpected situations. This time is influenced by several variables such as shelves dimensions, routing velocity and mass of the parts. Elaborated solutions are presented to model those variables emphasizing the route, which is considered as the main factor that influences the process time. The results obtained in simulations make understandable the dynamic system and are also capable of supporting managers in decisions such as estimating the required number of employees responsible to order consolidation.

Determining Safety Stocks in the Presence of Workload-dependent Lead Times
Seza Orcun (Purdue University), Sila Cetinkaya (Texas A&M University) and Reha Uzsoy (Purdue University)

Most classical stochastic inventory models assume that replenishment lead times are independent of the amount of orders placed. This assumption is clearly problematic in capacitated production systems, where queueing models show that mean cycle time is a nonlinear increasing function of resource utilization. We use a simulation environment created for rapid prototyping of supply chains to examine the problem of setting safety stocks in environments with workload-dependent lead times. We show that even when extensive historical data is used, conventional approaches to setting safety stocks fail to provide the desired service level when lead times are load-dependent, and suggest directions for future research.

A Hybrid Inventory Control System Approach Applied to the Food Industry
David Claudio, Jie Zhang, and Ying Zhang (The Pennsylvania State University)

The appropriate production and inventory control policy is a key factor for modern enterprises' success in competitive environment. In the food industry, most of food manufacturers adopt the make-to-order policy to improve their punctuality and flexibility, while some scholars provided other different opinions. This study provides a hybrid policy combining a make-to-order push strategy with priority with a make-to-stock pull strategy. In this policy, the pull strategy is considered for the regular demands while customers who tell their demand needs in advance are treated with a push strategy and are given a higher priority than those who don't share information. Through a set of simulation experiments by AutoMod model, this policy is proved to be of great efficiency, effectiveness and applicability.

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