In order to create a machining line layout that supports the principles of lean a systematic approach is needed to ensure that a wide range of factors are taken into consideration. Despite this, many companies today design new layouts mainly considering delivery times of machines and equipment, and available space in the factory. A combined literature and case study has aimed to identify the most important factors in a lean line layout and a supporting structure to apply these in the design or redesign of automated machining lines. Highly automated machining environments mainly distinguish themselves from the more thoroughly studied area of assembly line layouts in two ways. Primarily, automated machining lines separate the operator from the actual processing, making line balancing and productivity less dependent on the workstation design around the operator. Secondly, automated machining lines often involve a higher level of complexity, leading to a more comprehensive work load, requiring longer training times but also offering less repetitive assignments. Automation offers improved productivity, quality and ergonomics, but if the acquisition and allocation of automation is not substantiated by a well-developed strategy, automation risks contradicting lean principles by creating a more complex, rigid layout that places the machines in the center instead of the workers. Factors that are important in the design of the typically less automated assembly lines, such as minimizing the walking distance of the operator and rotating stations to provide meaningful work assignments, must in an automated machining environment give way to factors like visualization, material flow and maintenance. Visualizing a factory helps operators and managers learn and understand the factory better. Problems can be detected and corrected faster and disturbances in production can thus be reduced. A good material flow is straight with no intersecting flows, triggered by downstream demand and reduces unnecessary buffers and WIP that bind up capital and consume space. Finally, since the machines rather than the operators produce, a good maintenance is required to avoid unplanned stops. The value of teamwork and humans in production which are strongly advocated within lean remain important also in automated machining lines but acquires a new content compared to assembly lines. Teamwork in automated machining environments occur within a group of lines rather than in a single line and it is a major factor when it comes to competence development, production planning and worker satisfaction. While teamwork in assembly lines works to balance the production flow within the line, teamwork in automated machining lines has little or no effect on the line balancing. However, joint efforts in setups and in case of machine failures or worker absence help increasing productivity, and potentially smooth the production at the plant in its entirety. The empirical studies showed that there is no standardized way of working with machining line layout design and redesign, and factors considered were often coincidental and dependent on the functions and priorities of the participants at different layout meeting. To ensure that all factors are taken into consideration a supporting tool where the most important factors were divided into ten categories was developed. Layouts are evaluated and rated on one category at a time to support a systematic way of working. Ongoing discussions, adjustments and improvements to better comply with the factors are encouraged.

Thesis contains summarizing of main activities of technological projecting. The project itself analyzes the production of gear-boxes on a machine line, which caused transferring the production to a machining center. This real project is implemented on the basis of very detailed cost calculations substantiated by a positive result.

Actuellement, les fabricants sont soumis à une pression économique importante et à une concurrence internationale accrue due à la globalisation des marchés. Pour réussir, les fabricants doivent être capables de répondre rapidement aux changements de la demande en adaptant leurs systèmes de production. Cette adaptation aux changements peut être réalisée à travers multiples reconfigurations du système de production.Les travaux présentés dans ce mémoire portent sur l'élaboration des méthodes de recherche opérationnelle permettant d'accompagner le décideur lors de la reconfiguration d'une ligne de transfert ou d'assemblage. Ce problème apparaît lorsqu'un nouveau produit doit être fabriqué par une ligne existante ou lorsqu'il y a eu des changements dans les caractéristiques du produit. Par conséquent, il devient nécessaire de modifier la configuration du système de production tout en minimisant les coûts induits. Ces coûts sont évalués différemment pour les systèmes automatisésou manuels. Dans le premier cas, qui correspond au cas des lignes de transfert, pour limiter les investissements, il est souhaitable de réutiliser au maximum les équipements existants à condition que les contraintes techniques et technologiques soient respectées. Dans le cas des lignes manuelles qui sont représentées dans notre étude par les lignes d'assemblage, l'objectif est de minimiser les coûts liés à l'apprentissage des opérateurs causés par la réaffectation de leurs tâches.Les méthodes de résolution exactes basées sur la modélisation mathématique et la programmation linéaire en nombre mixtes ainsi qu'une méthode de type goal programming sont développées dans ce travail pour argumenter la prise de décisions lors de la reconfiguration des lignes de production. Les méthodes proposées ont été testées avec succès sur des échantillons de problèmes proches des cas industriels et ont montré leur efficacité. / Global competition causes fluctuations in product demand and requires more frequent modifications of product characteristics. As a consequence, the production systems have to be frequently adapted to new production requirements.This work develops new combinatorial optimization methods for supporting decision makers at the reconfiguration stage considered for transfer and assembly lines. If new products have to be manufactured at the line or existing products are modified, then the line has to be reconfigured in order to meet new production requirements. In highly automated lines, as the transfer lines, the reconfiguration problem is focused on the readjustment of the equipment. To reduce the investment costs, the decision makers aim to reuse the available equipment as much as possible. The existence of compatibility constraints between new operations to be performed and existing facilities makes the reconfiguration problem hard and combinatorial.In manual assembly lines also studied in this thesis, the reconfiguration problem mostly concerns the reassignment of tasks to workers ant the minimization of the cost of retraining operators.The developed methods are based on the mathematical modelling and mixed integer programming, a goal programming approach is designed as well. These methods were successfully tested on a dataset of problem instances close to real industrial problems. The obtained results show the effectiveness and the efficiency of the solution methods proposed.