Thesis abstract and approach

In machining processes, tools are one of the most dynamic and difficult to manage resources of the production system. This is mainly due to the wide diversity of existing tools, the need for various tools in order to process a batch, and the progressive loss of their cutting capacity. In order to ensure that the appropriate tools are available in the machines that need them to process the different batches, and at the required times, it is necessary to establish a tool scheduling and a management of cutting tools, that comprises those tasks necessary to prepare and transport the tools. In this way, production does not stop as a consequence of a lack of availability of the tool resource.
Cutting tools can be taken into account at different stages of production, form design to manufacturing. This thesis approach is dedicated at cutting tools in the most operational level of the shop floor. In this way, it only deals with tool scheduling and tool management at this level.
Tool scheduling and tool management cannot be carried out independently, but they must be integrated with the rest of functions related to the manufacturing process. Thus, this thesis takes into account process planning and production scheduling. Process planning is used to select the adequate cutting tools and working conditions for every machining operation. On the other hand, production scheduling assigns tasks to the machines.
The main objective of this thesis is to develop a proposal for scheduling and managing cutting tools that is integrated with process planning and production scheduling. The capacity of computer aided process planning of generating tool alternatives allow to realize job scheduling without taking into account tool resource. With these tool alternatives, it is possible solve interferences or incompatibilities because of the simultaneous use of the alternatives proposed by the process planner with the production scheduling, which involves the scheduling of tools on machines.
Tool scheduling, is the foundation that supports the proposal made in this thesis. The selection of all possible tool alternatives by the process planner for every operation creates incompatibilities or interferences with production scheduling, as the interaction with the tool resource is not taken into account. Those interferences arise from the simultaneous use of tools in the different operations, since the same tool cannot be used simultaneously by different machines. This thesis suggests solving those interferences iteratively, reducing the number of tool alternatives in the operations. The objectives set out in the resolution of interferences are the minimisation of tool movements, which enhances the stability of tools on machines, and the assignment of tools to the different operations according to their need for tools. Once the interferences have been resolved, different tool alternatives are assigned to each operation without any interference between them.
The existence of tool alternatives for the operations improves the management of the tool resource. Those alternatives are not only used to resolve the incompatibilities between operations by the tool resource with the production scheduling, but they also provide flexibility to the management of tools. The tool manager can use the alternatives to manage tool changes necessary due to cutting edge wear. Besides, these alternatives give some independence to the manager with regard to incidents, thus providing options that make it possible to continue the machining process when a particular tool is not available.