Planning

SEQUENCING IN MIXED MODEL NON-PERMUTATION FLOWSHOP PRODUCTION LINES USING CONSTRAINED BUFFERS

Author: FÒRBER GERRIT HARTMUT.
Year: 2006.
University: POLITÉCNICA DE CATALUÑA [www.upc.edu].
Place of defense: aula 28.8. ETSEIB. CAMPUS SUD.
Place of preparation: ETSEIB, Edifici H PLANTA 11 SD.

Summary: In a classic production line, only produced products with the same options. To manufacture variations of the same commodity used a different line or significant changes were necessary machinery. In recent years has been heightened the need to consider methods that allow more flexibility by offering a greater variety of products to customers. In general these methods are to produce different types of products on the same production line. Moreover, the philosophy of Just-In-Time, stocks and their derivatives costs, especially the stock of finished products are reduced significantly and consistently with a production batch is no longer favorable. With this background the production of various products or models on the same line simultaneously, without lots, acquires a large boom, and thus the complexity of managing the line increases. Most decisions on the phases of sequencing and scheduling becomes essential. There are several designs of lines that can allow resecuenciación, such as department stores use (Automatic-Storage-and-Retrieval-System), a part of the process to decouple from the rest of the line; have stores with limited spaces outside the line ; existence of hybrid lines or flexible, enabling the division and union lines, or change the attributes of the pieces rather than changing the position on the stream. The resecuenciación pieces inside the line becomes more effective when it presents a time or extra cost, known as setup-time and setup-cost necessary in many cases, when a station, the next piece is another model. This thesis considers the case of a flow line with the possibility of resecuenciar pieces between consecutive seasons. The stores are located outside the line and in a first step accessible from a single station (case of intermediate storage). Then use a single warehouse, centralized, accessible from several stations. In both cases it is thought that a piece, because of its size, may not be able to fill certain vacancies warehouse either intermediate or centralized. As a result of the study and analysis of the State of the Art, which led to delimit the case study, proposes a Novel Classification flow lines not permutation. This classification was essential, because in the current literature has not been classified in depth this type of production, so far existing classifications do not consider the many options presented to include the possibility of resecuenciar pieces in the line. This thesis presents different formulations: an exact method, using a programming model restrictions (PLC), several hybrid method, based on PLC, and a heuristic method, using a Genetic Algorithm (GA). During the course of this work, the studies that have been conducted show the effectiveness of resecuenciar. The results of simulated experiments show the benefits dipped to a centralized warehouse, compared with the intermediate warehouses. The issue is considered important for a variety of applications flow lines such as the chemical industry, where customer orders have different volumes and on the same line there tanks different volumes for resecuenciar. Also, lines which are used lots divided (split-lot) in order to investigate changes in processes, as well as in the semiconductor industry, or in the production of prefabricated houses, where they make big and small walls passing for consecutive seasons in which electrical circuits are installed, pipes, doors, windows and insulation.

PLANNING