A jobshop is a manufacturing system well-known for its operational complexity due to the conditions under which it operates, such as instability of order volumes, product mix, product routings, customer bases, and etc. A fundamental approach to improve the performance and efficiency of jobshops has been to transform the Functional Layout that they traditionally use into a Cellular Layout. Functional Layouts have noticeable advantages such as flexibility and machine utilization; however, they also have major disadvantages such as high production lead times, high WIP (work-in-progress) inventory levels, and complex scheduling. In comparison, Cellular Layouts provide shorter production lead times, lower WIP inventory levels, simpler scheduling, and better control of product quality.
However, Cellular Layouts have major disadvantages such as low machine utilization, high cost of cell reconfiguration when demand or product mix change, and high risk of disruption to production due to machine breakdowns and operator absenteeism. These disadvantages are especially harmful for jobshops because they operate in a high-mix low-volume (HMLV) environment. Therefore, a complete reorganization of the Functional Layout of a jobshop into a Cellular Layouts, especially when operating in a HMLV environment, is never advisable. At the same time, retaining the existing Functional Layout does not make a jobshop-type manufacturer competitive. These major shortcomings of these two extremes of facility layouts for jobshops encouraged as to investigate alternative layouts that retain the advantages of both layouts, and mitigate their disadvantages and the weaknesses.
In this dissertation, two novel layouts that integrate the attributes of the traditional Functional, Cellular and Flowline layouts are introduced. These layouts are a Modular Layout and a Hybrid Flowshop Layout. The mathematical models, optimization methods and heuristics for design of these two novel layout configurations are introduced. Performance analyses were done to compare the traditional and proposed layouts. The role of the PFAST software, which was developed during the course of the dissertation, in a man-machine interactive process to design any facility layout is explained.
|Commitee:||Mount-Campbell, Clark, A, Sadayappan, Ponnuswamy|
|School:||The Ohio State University|
|Department:||Industrial and Systems Engineering|
|School Location:||United States -- Ohio|
|Source:||DAI-B 78/11(E), Dissertation Abstracts International|
|Keywords:||Facility layout, Hybrid flowshop layout, Layout simulation, Modular layout, PFAST|
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