M. Bulent Durmusoglu

A team-oriented design methodology for mixed model assembly systems

Team-oriented approaches are widely being used in modern real life assembly systems, as are other modern systems. In this paper, first the literature of single and mixed model assembly line balancing, which plays an important role for the design of assembly systems, is reviewed. The associated literature matrixes reveal that team-oriented approaches do not have an intensive research area. Second, a team-oriented mathematical programming model for creating assembly teams (physical stations) in mixed model assembly lines is devised. Owing to the fact that this model is NP hard, a scheduling based heuristic algorithm is developed. The mixed model assembly line design methodology, which includes a team-oriented algorithm as a step, is proposed. Both model sequencing and worker transfer systems are included in the methodology. The algorithms for each step of the methodology are also coded by using MATLAB and MS Excel is used as the user interface. Furthermore, the presented methodology was applied in a chosen segment of a real life mixed model tractor assembly system.

GT cells design and implementation in a glass mould production system

Cellular production is maintained to be a popular manufacturing and management philosophy, which is increasingly interested and intensified. In this study, group technology cells design and implementation project in a real life glass mould production system is described. All the stages of the project, the difficulties encountered, the strategies developed that overcome these difficulties and the performance improvements after the implementation of cellular production are explained in detail.

Analysis of the conversion from a job shop system to a cellular manufacturing system

Abstract Cellular Manufacturing System is an efficient manufacturing system which can be directly integrated with the production functions. However the conversion from an existing job shop system to a cellular manufacturing system is a huge job. In this study, modelling and economic analysis of this conversion are performed in order to justify the cellular manufacturing system. A selected real life manufacturing system operating under job shop system conditions is designed as ten cells. This new system and the existing system are modelled and simulated by SIMAN. Then an economic analysis is performed using the simulation results. Inventory carrying cost and machine and materials handling equipment duplication costs are primarily considered in this economic analysis.

Integrating parts design characteristics and scheduling on parallel machines

Setup times have an important effect on providing quick response to the external besides internal customers. As well as eliminating setup activities, jobs with sequence-dependent setup times should be scheduled efficiently so as to reduce setup times. In this paper, a scheduling methodology which considers parts design characteristics is presented for parallel machines. With respect to the roadmap of the methodology, a parts design characteristics based scheduling algorithm is developed in order to reduce total setup times. When evaluating the performance of sequencing methods, the cable cutting-stripping-crimping (CSC) process of a real life wiring harness production system is focused. In the current scheduling system of CSC division, cable sequences are developed semi-manually by CSC supervisors. Making the proposed methodology compatible with cable sequencing, an expert system is developed so as to reduce the burden of supervisors and improve effectiveness. Performance comparison of scheduling algorithms is based on deviation from the lower bound for the total setup time as well as previously implemented semi-manual cable sequences. With respect to performance comparison, parts design characteristics based scheduling algorithm has resulted in 6.81% reduction of the total setup time compared to implemented semi-manual cable sequences (MCS) for 45-day production data.

An integrated job release and scheduling approach on parallel machines

We integrate the mathematical programming models of JR with job scheduling.We present a methodology which integrates JR and job scheduling on parallel machines.Application of the methodology in electric wire-harness industry through VSM. This paper presents a new job release (JR) and scheduling methodology for one-stage parallel machines where sequence dependent setup times exist. A decision support system (DSS) based on job release is developed in order to enable the application of the methodology. First, mathematical programming models for both job release and job scheduling are devised. Then, due to the NP-hard nature of the problems, heuristics are proposed. As for the interaction between JR and scheduling, job scheduling is integrated with job release for the proposed heuristic solutions so that the capacity achievement provided by scheduling can be utilized for job release. In brief, product design characteristics oriented scheduling affects JR in the proposed approach. Moreover, value stream mapping (VSM) approach is used with the aim of stating the effect of the proposed methodology. Furthermore, the presented methodology was applied in a real life electric wire-harness production system. The application, based on 120-day production data, revealed that the proposed methodology provided 25% decrease in in-plant manufacturing lead time.

Minimising utility work and utility worker transfers for a mixed-model assembly line

Mixed-model assembly lines (MMALs) are types of production lines that are able to respond to diversified costumers’ demand for a variety of models without holding large inventories. The effective utilisation of a mixed-model assembly line requires the determination of the assembly sequence for different models. In this paper, two objectives are considered in a sequential manner, namely minimising: (i) total utility work, which means work from an additional worker to assist an operator for completion of an assembly task; and (ii) utility worker transfer which states the move of a utility worker to a different segment of the assembly line. First, due to the NP-hard nature of the problem, three heuristic methods are proposed with the aim of minimising total utility work. Then, the solutions which are obtained from the heuristics are improved in terms of the total number of utility worker transfers via a local search based method. Furthermore, the solution approach was applied in a real life mixed model tractor assembly line. Results validated the effectiveness of sequencing approach in terms of solution quality.

Team based labour assignment methodology for new product development projects

We develop a team based labour assignment methodology for NPD projects.Proposed hierarchical methodology integrates VSM, DSM and clustering techniques.The aim is to eliminate waste and create flow to reduce lead time.A real life application is performed to evaluate the proposed methodology.The results tested by simulation have promised significant lead time reduction. This study explores the organizational aspects of new product development projects and proposes a new team-based labour assignment methodology. The proposed hierarchical methodology focusses on the project value stream and aims to shorten lead time through waste reduction. Lean product development tools, such as clustering and design structure matrix tools, are integrated with the methodology. A detailed real-life case study is presented and the proposed methodology is evaluated using discrete event simulation. Experiment results show that the proposed methodology and team-based structure provide superior lead time performance when compared to conventional organizational setting. This study contributes to existing literature by presenting evidence of the effect of teams on NPD lead time performance.

Axiomatic Design for Lean-oriented Occupational Health and Safety systems

We provide an axiomatic design (AD) for OHS system under lean production principles.Standard Risk Model is integrated with Kinney Risk Assessment Method.The developed roadmap by AD was planned to apply in a real life shipyard system. The use of facilities provided by industrialization and technological developments has led to increase in occupational diseases and accidents in workplaces. A sheer success in Occupational Health and Safety (OHS) is possible when safety activities for employees, production and business are considered synchronously. OHS systems, where scientific research oriented technological advances applied, are required to be designed with the aim of preventing OHS related problems and their effects in sustainable manner. In this study, a systematic approach is proposed for design of Lean-oriented OHS systems by using Axiomatic Design principles. A holistic roadmap is obtained as the output of the study for the application of OHS system to a production system. The proposed OHS system design is applied to a real life shipyard system from shipbuilding industry and its feasibility is demonstrated.

Model Sequencing and Worker Transfer System for Mixed Model Team Oriented Assembly Lines

Assembly lines are the most commonly used method for a mass production environment. Their main purpose is to increase efficiency by maximizing the ratio between throughput and required costs. However, in the last few decades, market demands have changed enormously. The emphasis is now on shorter lead times, larger product variety, higher quality and more customized options. At the same time, socioeconomic conditions have improved and workers have a greater interest in work satisfaction. Increasing the importance of quality and flexibility of the assembly system, while providing a satisfying work environment, these changes lead to the utilization of teamwork for assembly line design. Unlike conventional assembly lines, team-oriented assembly lines consist of multimanned workstations, where workers’ groups simultaneously perform different assembly works on the same product and workstation. In addition, it is also different from installing parallel (multiple) stations, where individual products are distributed among several workers who perform the same tasks but on different products (Dimitriadis, 2006). Team-oriented assembly systems in which workers are organized in groups outperform traditional assembly systems in terms of cost, lead time, flexibility, quality, and worker satisfaction. However, in such lines, performance is affected in a negative way on the condition that high level of variability among station times result in utility and idle times. Some research in the literature states the convenience of team oriented assembly systems for current market needs when compared to conventional assembly lines the stations of which consists of one worker. For instance, Wild, R. (1975) examined the types, basic design considerations and benefits of teamwork. The author stated that implementing teamwork yields good results in quality development and workers may benefit via increased confidence through the development of social skills in a teamwork environment. Groover, M. P. (2001) maintained that compared with workers on a conventional line, the members of an assembly team achieved a greater level of personal satisfaction at having accomplished a major portion of product. Bukchin, J. et al. (1997) provided a straightforward study applying teamwork approach to assembly line design. According to the authors, team-oriented assembly system approach should be used to overcome the disadvantages of classical assembly design: low quality, poor working environment, long flow time and high costs of material handling. In spite of the fact that teamwork approach is applied in assembly lines frequently, very few reported studies have utilized. Johnson, R. V. (1991) discussed the fact that labor cost increases with both the number of the teams and the percentage of tasks that