No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 139-140). Also available via the Internet.

LD2668 .T4 1941 T71 / Master of Science

No description available.

No description available.

Thesis (M.Eng.(Industrial Engineering))--University of Pretoria, 2008. / Includes bibliographical references.

This research focused on an important aspect of production, machine changeover, or setup time. Setup time is defined as the elapsed time between producing the last part from the most recent lot to the first part of an incoming lot. The research had four objectives. First, an existing method to reduce machine changeover time was evaluated in a high-precision machine cell (HPMC). Second, the causes and effects of setup problems in an HPMC were identified. Third, a method to reduce setup time was developed to more fully address some of the identified problems. Fourth, the developed method was evaluated in another HPMC. After reviewing published setup reduction methodologies, the Single Minute Exchange of Dies (SMED) approach was selected for evaluation in machine cells. According to its developer, SMED can typically reduce setup time by 70 to 90%. The case study did not fully support this claim. Possible explanations for the mixed results were developed. Also, a number of setup problems were not fully corrected. These problems included machine and tooling failures, delays from tasks not completed at the machine area, and labor-related problems. A method to reduce setup time was developed. The method applied the work simplification approach to reduce setup time. The developed setup reduction method consisted of five steps: (1) document the existing method, (2) simplify the current method while using the same tooling and procedures, (3) identify opportunities to reduce setup time, (4) prioritize the opportunities and (5) implement the prioritized projects. The method includes the basic setup reduction principles of SMED and addresses problems that were not fully corrected by SMED. The developed method was tested in another high-precision machine cell. An additional 22% reduction in setup time occurred as a result of correcting problems not fully addressed by SMED. It was concluded that because the new method focused on the manpower, materials, and methodology used during a changeover, it reduced setup time further than existing methods. / Master of Science

Bending process is an important forming process in most industrial fields. Springback and cross-section distortion are commonly faced problems in bending process. Springback behavior of closed and open section beams changes with different parameters such as cross-section type, cross-section dimensions, bend radius and bend angle. For closed sections like tube, the dominating problem is cross-section distortion. The thickness of the tube at intrados (inner surface of tube being in contact with die) increases, whereas the thickness of the tube at extrados (outer surface of tube) decreases. Furthermore, another cross-section distortion type for tubes is flattening at extrados which is undesirable in some manufacturing operations. The present research, using finite element method, focuses on investigating the springback behavior of commonly used aluminum beams which are T-Shaped, U-Shaped and tubular for different cases. A series of analyses is performed for a beam and the changing parameters in the analyses are bend radius and thickness. Furthermore, for tubes, the effects of axial force on springback behavior are investigated. It is seen that the axial force causes stretching and the springback angles are decreased. Moreover, in order to overcome cross-section distortion in flattening for tubes, different internal pressures are used and the effects of internal pressure are investigated. By applying appropriate internal pressure, the flattening distortion is mostly eliminated. Conclusions are drawn revealing springback behaviors and cross-section distortions with respect to bend radius, bend angle, thickness, axial pull and internal pressures. They are in good agreement with other published researches and experimental results. Therefore, the models can be used to evaluate tooling and process design in bending operations.

In this study, an operational (short term) flexibility management approach is proposed for make-to-order companies with flexible shops. Order Review and Release (ORR) techniques and typical Flexible Manufacturing System (FMS) decisions are combined in this method. The proposed method prepares a shop environment by allocating process and routing flexibility types at different levels to the shop in each production cycle. Variety, volume, and criticality of the part types in the pool and the anticipated orders constitute the main inputs for flexibility allocation. A flexibility management policy is introduced and determination of the proper policy is realized with the integrated utilization of mathematical programming and simulation modeling. An experimental study is performed to investigate the effects of proposed method on a hypothetical flexible shop. Results show that with an appropriate policy, periodical and online flexibility management can be an effective tool to cope with uncertainty in demand if combined with ORR techniques.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaves 164-168. / by Joseph Githu Kimemia. / Ph.D.