Papers by Author: S. Martínez

Abstract: The best is to read these instructions and follow the outline of this text. The text area for your manuscript must be 17 cm wide and 25 cm high. The High Performance Manufacturing Group of the Faculty of Engineering of Bilbao has a workshop fully-equipped. In this way, these machine tools are valid both to support research carried out by the Group and also to improve teaching lessons, both theoretically and practically. In this paper, the case of a five-axis milling machine was presented and analyzed. Each year, the new students are taught to design various systems of the machine and they are also encouraged to make some practical tests. This dual use of machines is very useful since it allows to carry out high level researches, as well as to train new students in theoretical and practical issues.

Abstract: The main disadvantage for industrial application of new processes based on laser surface treatments, such as laser hardening, quenching or precipitation hardening, is the prior experimentation needed to determinate the optimum conditions for processes. The presented work is focused on the development of a tool based on a semi-empirical model to predict accurately the thermal field and thickness of the head affected zone in laser surface treatments in order to avoid the previous experimental setups of this processes. The conventional thermal models are focused on solving the differential equation of temperature field, considering the laser as heat source and thermal properties of each material. However, during the rapid heating treatment processes of metal surfaces are some unknown heat sinks such us metallurgical transformations or a changeable material absortivity that must be taken into account. The model has been adjusted and validated with experimental data for AISI 1045.

Abstract: In laser surface treatment the laser beam is used as energy source for surface modification improving aspects such as mechanical properties, tribology or surface texture. Modeling tools have special interest in processes with many variables, like laser surface processing, in order to minimize the tryout testing to find the optimal process parameters. The work presented here focuses on the prediction of the final topography in laser polishing process. By FFT analysis of the surface profile it is possible to get the different frequency components of the initial topography. On the other hand, thermal field simulation was carried out to evaluate the melt duration. Matching this with the spatial frequency damping during process, the reconstruction of the processed topography was obtained.

Abstract: The laser cladding process is based on the generation of a melt-pool in a substrate where a filler material is injected, generating a high quality clad with a minimum heat affected zone. This process is industrially used to generate coatings over wear or damaged surfaces, being an alternative to traditional deposition techniques. One of the most important aspects for its industrial application is to know the clad geometry in order to calculate the deposited layer thickness. This work presents a model in which, starting from the concentration of injected material and the melt-pool geometry, clad height is finally estimated. Both input variables are obtained by two previous validated models. On one hand, the melt pool is estimated by a thermal model based on the finite difference method, and on the other hand, concentration of injected material is provided by a particle concentration CFD model. This data is used in a mass balance over melt-pool area in order to estimate the deposited clad height.