Publikationsserver der RWTH Aachen University
Methodisches System zur Auslegung von kostenoptimalen und prozessstabilen Fertigungsverkettungen
Abstract
dc:descriptionIntention of this task has been to verify that an optimal definition of manufacturing tolerances along the process chain can be achieved by a selective precocious, cost-optimal and stable manufacturing planning. This was carried out by a development of a framework system for the cost-optimal and stable design of manufacturing chains without prior definition of manufacturing tolerances along the process chain. The system starts with the assignment of design specifications with concrete manufacturing processes. A new model was developed, weighting the selected manufacturing processes on basis of their influence on product functionality, work piece characteristics and product purposes. Based on the methods of Fallböhmer and Trommer a manufacturing chain was generated using the selected manufacturing processes. In the following system modules, this manufacturing chain was used as basis for the creation of process alternatives. The process alternatives insist of the same manufacturing processes, which however differ in their parameters and actuating variables. Since the variation of the actuating variables within the allowed spread results in a huge quantity of process alternatives, initially a new model for the alternative reduction was developed. This model is based on the methodology for design of experiments and reduces the existing testing plans. By means of the testing plans, the influences of the manufacturing processes and their parameters on the work piece characteristics were determined. Therefore, an interface to a comprehensive manufacturing-orientated technology knowledgemanagement system was created by the first time. In this manner, the required criteria can be calculated on basis of existing technology knowledge. This can be achieved by practical tests, simulations and expert knowledge. As the determined criteria partially show variances which have direct influence on the resulting cost, the variances were considered in the next steps for the first time. Based on the resulting variances and work piece intermediate conditions, in the following a method for the identification of risky processes was presented. Hereunder those manufacturing processes are meant, which disperse without any mathematical law. In that case, an instable process can be assumed and reproducible process results can not be achieved. Similarly, processes resulting in work piece scrap are rejected. The remaining process alternatives are realisable and achieve the given design specifications. They merely differ in their cost and manufacturing times. For this reason, the manufacturing cost and times are being calculated on basis of technology knowledge and the work piece intermediate conditions. The allowed scrap has an essential influence on the cost and times. By defining a limit – alternatively for the scrap, the cost and/ or the times – a calculation of the allowed manufacturing tolerances along the process chain is performed. Finally, the new developed benchmarking of the process alternatives allows a quantitative comparison of the alternatives regarding the criteria cost, time and scrap. As support, the influence of the manufacturing process on the required product objectives and functionalities is being used. Where exists, sometimes already existing methods were used in the modules. This did not affect the development of the framework system for cost-optimal and stable design of process chains. The design of better methods would result in an increased accuracy of the calculated results. Concluding the review of the developed concept has been carried out by implementation within a software-demonstrator and tested by means of a case study.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2008
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Willms, Holger
- Contributors dc:contributor
-
- Klocke, Fritz
Subjects
dc:subject × 9Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger