[en] The micromachining process, the same as any other industrial process, must offer high reliability so that it can be integrated in the manufacturing industry. In order to ensure their reliability, machining processes like micro milling, must obtain, without error, the precision and surface roughness required for a predetermined amount of time. To achieve such reliability, it is essential to ensure a long and stable tool life. In this doctoral thesis these three concepts have been analyzed, some of them in an experimental way and others in both a theoretical and an experimental way. The influence of the cutting conditions on the tool's life and the surface finish, have been studied experimentally. The precision has been studied both theoretically and experimentally. The study of accuracy has been approached from different angles since its loss depends on several factors. On the one hand, the effect of temperature on accuracy has been studied. The principal responsible for the thermal expansion suffered in the Z axis is the heat generated in both the head's motor and in its bearings. As a result of this research, a compensation model of these expansions has been proposed. On the other hand, a protocol has been developed in order to reduce the expansions' negative effect. Thanks to this protocol, it has been managed to reduce the effect of these expansions in the workpiece's accuracy. To improve accuracy in the X-Y plane, a method has been developed to compensate the machine and the process's repetitive errors which damage the workpiece's accuracy. After having measured and analyzed the repetitive errors generated in the machined workpiece, this method properly modifies the X-Y coordinates of the CNC machining program, in order to reduce errors in further machining workpieces. Furthermore, an experimental analysis has been carried out of the variables that can compromise the micromachining success, such as, cutting forces, minimum chip thickness, tool's stiffness and radial run-out. Due to the added difficulty that micro scale generates, new testing systems and protocols have had to be developed. Owing to the high cost of the experimental tests, a strength model, which is adapted to micro milling, has been developed. Finally, using the previously mentioned model, a theoretical study has been carried out on the effect that certain parameters have in the workpiece's accuracy. Such parameters are the following: the micro milling's cut's direction (climb milling- conventional milling), the tool's helix angle and tool's wearing.

[eu] Mikromekanizazioak, beste edozein prozesu industrialek bezala, ekoizpen industrialean txertatu ahal izateko fidagarritasuna behar du. Mikrofresaketa bezalako txirbil-harroketazko prozesuek fidagarritasuna bermatzeko, piezaren zehaztasun eta gainazal zimurtasun egokia lortu behar dute denboran zehar hutsik egin gabe. Hori lortzeko beharrezkoa da erremintaren bizi iraupen luze eta egonkorra. Doktoretza tesi honetan hiru kontzeptu horiek aztertu dira, batzuk era esperimentalean eta beste batzuk era teoriko eta esperimentalean. Erremintaren bizi iraupena eta gainazal zimurtasuna esperimentalki aztertu dira, ebaketa baldintzek hauengan duten eragina jakiteko. Zehaztasuna era esperimentalean eta teorikoan aztertu da. Zehaztasunaren azterketa, hainbat esparrutan jorratu da, bere galera eragiten duten faktoreak iturri askotakoak baitira. Alde batetik, tenperaturak zehaztasunean duen eragina ikertu da. Z ardatzean sortzen diren dilatazioen eragile nagusia, makinaren buruko motorrak eta errodamenduek sortzen duten berotasuna da. Ikerketa honen ondorio gisa, dilatazioen konpentsazio eredua proposatu da. Bestalde, dilatazioen ondorio kaltegarriak ekiditeko, azterketa esperimentalean oinarriturik lan protokoloa garatu da. Protokolo honi esker, dilatazio hauek piezaren zehaztasunean duten eragina gutxitzea lortu da. X-Y planoan zehaztasuna hobetzeko, makinaren akats errepikakorrek piezarengan sortzen duten zehaztasun galera konpentsatzeko ere metodo bat garatu da. Metodo honek, makinak berak dituen akats geometrikoen ondorioz eta prozesuaren kontrolik gabeko akatsen ondorioz sortzen diren akats errepikakorrak aztertu ondoren, zenbakizko kontroleko programa modifikatzen du, hurrengo piezetan akatsak txikiagotuz eta zehaztasuna hobetuz. Bestalde, mikrofresaketa eragiketa baten arrakasta baldintzatu dezaketen ebaketa indar, gutxieneko txirbil lodiera, erremintaren zurruntasun eta eszentrikotasunaren azterketa esperimentala egin da. Azterketa esperimental hauek mikroeskalan egiteak zailtasun handia duenez, hauek egin ahal izateko ekipamendu eta metodo bereziak ere garatu behar izan dira. Azterketa esperimentalak duten koste handia dela eta, mikrofresaketara egokitutako ebaketa indar eredu bat garatu da. Eredu hau erabiliz, piezaren zehaztasunean zenbait parametrok duten eragina teorikoki aztertu da. Hala nola, ebaketa-norantzak, erremintaren helize angeluak edota erremintaren zorroztasunak ebaketa indarretan duten eragina. Tesian zehar egin den beste eginkizun nagusi bat, Mondragon Unibertsitateko Goi Eskola Politeknikoko Mekanika eta Ekoizpen Industrialeko sailean mikromekanizazio entsegu esperimentalak egiteko laborategia garatzea izan da.