Comprehensive machine cell/part family formation using genetic algorithmsSaeed Zolfaghari; Ming Liang
2004 Journal of Manufacturing Technology Management
doi: 10.1108/17410380410547843
The solution quality of a comprehensive machine/part grouping problem, where the processing times, lot sizes and machine capacities are considered, may not be properly evaluated using a binary performance measure. This paper suggests a generalized grouping efficacy index which has been compared favorably with two binary performance measures. A genetic algorithm using the generalized performance measure as the objective is developed to solve the comprehensive grouping problems. The algorithm has been tested using a number of reference problems with processing times being randomly assigned to all operations. The effects of three major genetic parameters (population size, mutation rate and the number of crossover points) have also been examined. The results indicate that, when the computational time is fixed, larger population size and lower mutation rate tend to improve solution quality while the number of crossover points has no significant impact on the final solution.
An application of design of experiments for optimization of plastic injection molding processesShad Dowlatshahi
2004 Journal of Manufacturing Technology Management
doi: 10.1108/17410380410547852
Making improvements in products or in processes can be one of the most challenging tasks confronting an organization. This paper uses design of experiment (DOE) to identify causes of defects associated with plastic injection molding processes at the early phases of designing processes and operations. A detailed eight‐phase methodology is offered through which an identification of defects and effective solutions for their removal could be done. The paper also shows how the parameters of the problem could be established and how DOE could be applied to achieve the stated objectives by using the results of only 18 and ten DOE test runs. The results of the initial experiments are subjected to a verification procedure to determine their viability and accuracy. As a result of this experiment, the company was able to make the changes needed to reduce the cycle time required to produce products and thus, increase productivity while maintaining high quality standards. In conclusion, an assessment of the results is provided and the necessary conditions and prerequisites for the effective utilization of the methodology are presented.
An empirical study of facility layout using a modified SLP procedureTe‐King Chien
2004 Journal of Manufacturing Technology Management
doi: 10.1108/17410380410547861
Although many new technologies have been developed in facilities design, the systematic layout planning (SLP) procedure is the most widely used among enterprises and the academic world. The practical applications in a traditional SLP require intricate steps yet their results lack stability. It is difficult to attain reasonable results from alternatives derived via traditional SLP. This study proposes concepts and algorithms such as grouping, compounding, and hypothetical distance to modify procedures and enhance practicality in traditional SLP. The proposed modifications were applied to a case study. The results were superior to solutions derived from computer software simulations and by supervisors of the case company. This study believes that the proposed modifications and procedures can enhance the enterprise's ability in facility design.
Manufacturing flexibility and variability: an overviewSami Kara; Berman Kayis
2004 Journal of Manufacturing Technology Management
doi: 10.1108/17410380410547870
Flexibility has become one of the most useful and necessary weapons in many of today's competitive markets. For companies in situations considering investments in flexibility, it is necessary to assess carefully exactly what flexibility could benefit the company's operations, and how this flexibility can be achieved. Different manufacturing situations are associated with different levels of uncertainty and variations, and therefore call for different sorts of flexibility. Although flexibility has been argued to be available (to a certain point) without major investments in technology, it can be assumed that flexibility is most likely to come at a price. A company should therefore spend considerable effort on identifying what flexibility would be of benefit to the organisation to enhance their performance, and thereafter assess how to achieve it. This paper provides a comprehensive analysis of variability and uncertainty, and therefore, the need for flexibility within an organisation by examining market and manufacturing process related factors. Each factor is further examined to find out relevant flexibilities and corresponding methods, tools, and techniques to be used by suggesting proposed manufacturing approaches to organisations. The human factor is suggested as an essential flexibility component as well as a key contributor for selecting, developing, improving and implementing flexibilities in order to succeed in markets that are accelerating and becoming more turbulent.
A production, distribution and investment model for a multinational companyZubair M. Mohamed; Mohamed A. Youssef
2004 Journal of Manufacturing Technology Management
doi: 10.1108/17410380410547898
Considerable research literature exists on production planning, distribution, and investment models. In most cases they have been treated independently in an environment of low inflation rates. Unfortunately, work extending these problems to multinational companies is sparse. This paper develops an integrated production planning, distribution, and investment model for a multinational firm that produces products in different countries and distributes them to geographically diverse markets. Since multinational corporations operate in different countries under varying exchange and inflation rates, varying opportunities for investing, and differing regulations, these factors should be included in the decision process. In the modeling, the paper incorporates these factors and elicits the performance of the model through an example and discusses the results. The results indicate that the exchange rates and initial capacity levels of the firms have significant effects on the production, distribution, and investment decisions, and consequently, on the profit.