Browsing by Author "Ostra, Txomin"
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Item Analysis of the Machining Process of Inconel 718 Parts Manufactured by Laser Metal Deposition(2019-07-01) Ostra, Txomin; Alonso, Unai; Veiga, Fernando; Ortiz, Mikel; Ramiro, Pedro; Alberdi, Amaia; FABRIC_INTEL; Tecnalia Research & InnovationLaser metal deposition (LMD) is an additive manufacturing process that allows the manufacturing of near-net-shape products. This could mean significant savings in terms of materials and costs in the manufacturing of high-performance components for the aeronautical industry. In this work, an analysis of how the LMD processing of alloy 718 affects the final machining has been carried out. For this purpose, a comparative study has been done by means of the monitoring of the end milling process of a part manufactured by LMD and a rough-milled part from forged material. Differences between process outputs such as chip morphology and cutting forces were studied. Material characteristics such as microstructure, hardness and mechanical properties were also analyzed.Item Comparison of dry and liquid carbon dioxide cutting conditions based on machining performance and life cycle assessment for end milling GFRP(2022-09) Khanna, Navneet; Rodríguez, Adrián; Shah, Prassan; Pereira, Octavio; Rubio-Mateos, Antonio; de Lacalle, Luis Norberto López; Ostra, Txomin; FABRIC_INTELIn the present scenario, citizens’ concern about environment preservation creates a necessity to mature more ecological and energy-efficient manufacturing processes and materials. The usage of glass fiber reinforced polymer (GFRP) is one of the emerging materials to replace the traditional metallic alloys in the automotive and aircraft industries. However, it has been comprehended to arise a sustainable substitute to conventional emulsion-based coolants in machining processes for dropping the destructive effects on the ecosystem without degrading the machining performance. So, in this study, the comparison of the two sustainable cutting fluid approaches, i.e., dry and LCO2, has been presented based on machining performance indicators like temperature, modulus of cutting force, tool wear, surface roughness, power consumption, and life cycle assessment (LCA) analysis for end milling of GFRP. The cutting condition of LCO2 has been found to be superior in terms of machining performance by providing 80% of lower cutting zone temperature, tool wear, 5% lower modulus of cutting force, and reduced surface roughness with 9% lower power consumption that has been observed in the case of LCO2 in comparison with dry machining. However, to compress the CO2 for converting in liquid form, a higher amount of energy and natural resources is consumed resulting in a higher impact on the environment in comparison with dry machining. Considering the 18 impact categories of ReCiPe midpoint (H) 2016, 95% higher values of impacts have been observed in the case of LCO2 in comparison with dry machining.Item Low frequency vibration assisted drilling of PC1000 polycarbonate(2019) Alonso, Unai; Goirigolzarri, Borja; Ostra, Txomin; de Lacalle, L.N. Lopez; FABRIC_INTELA challenge in drilling polymers is their very low melting point, especially when holes with a large length-to-diameter ratio are required. One opportunity to avoid chip accumulation is the use of low vibration assisted drilling. In the present work, the comprehensive knowledge acquired from the machining of metals is transferred to drilling of polycarbonate PC1000. The first research objective of this work was to evaluate if the kinematic models proposed in literature could predict the onset of discontinuous chip generation. To do so, a series of drilling tests were performed with a MITIS tool holder varying vibration amplitude and hole length. During the tests, thrust force and workpiece temperature were registered and, afterwards, hole diameter and surface roughness were measured. The results showed that a kinematic model can be useful to predict the onset of discontinuous chip generation. It was also concluded that surface roughness increases with vibration amplitude until the onset of chip breakage is reached. Furthermore, a correlation between temperature and surface roughness was detected. Regarding cutting forces, a relationship was observed between the thrust force signal amplitude and the amplitude vibration of the MITIS tool-holder. This correlation could be useful to calibrate other future designs of tool holders.