Material Extrusion (MEX) additive manufacturing (AM) of ABS polymer components often requires post-process machining to achieve the necessary dimensional precision and surface quality. However, the influence of printing parameters and tool–material interaction in hybrid manufacturing remains insufficiently explored. This study investigates the impact of initial hole size (D_start), build orientation, and cutting parameters (cutting speed and feed rate) on the dimensional accuracy and surface roughness of machined holes in ABS-M30 specimens. Samples were fabricated in vertical and horizontal orientations and subjected to drilling in solid material and enlargement of printed pilot holes using a twist drill on a 5-axis machining center. Dimensional deviation and surface roughness (Ra, Rz) were evaluated using coordinate metrology and profilometry. The results showed that the smallest machining allowance (0.062 mm per side) was insufficient to completely remove the printing-induced surface texture, resulting in significantly higher and more variable Ra and Rz values. This distinct low-machining-allowance regime was confirmed by statistical analysis and representative optical observations. Conversely, a machining allowance of 0.565 mm per side (corresponding to D_start = 9 mm) resulted in substantially lower surface roughness (Ra ≈ 1.6 µm). Vertical build orientation generally provided better surface quality than the horizontal orientation, which was consistent with fewer visible surface features in the selected optical fields of view. All machining conditions resulted in negative dimensional deviations, indicating elastic recovery of the ABS material after machining. An exploratory multi-response ranking showed that the lowest composite quality scores for overall final hole quality were associated with D_start = 10 mm (machining allowance of 0.062 mm per side). When the analysis was limited to the machining-dominated regime, the lowest score was obtained for the vertical build orientation, D_start = 9 mm, a cutting speed of 40 m/min, and a feed rate of 0.2 mm/rev. These findings provide preliminary guidelines for selecting hybrid manufacturing conditions for MEX-manufactured ABS-M30 components.

La microgeometría del filo de las herramientas de corte tiene un efecto determinante tanto en su duración como en la calidad del acabado de la pieza. Actualmente se están logrando avances significativos en la implementación de técnicas que permiten obtener con elevada precisión redondeos de arista de corte tanto simétricos como asimétricos. Para aprovechar el potencial de estas tecnologías es necesario determinar el efecto de los distintos tipos de redondeo de filo sobre el rendimiento de la herramienta en función de los parámetros de corte y material mecanizado. En este trabajo se han desarrollado modelos numéricos bidimensionales de procesos de mecanizado de la aleación Ti6Al4V considerando distintas preparaciones de filo y parámetros de corte. Estos modelos han sido validados a partir de resultados experimentales obtenidos de referencias científicas internacionales. Los resultados obtenidos confirman la necesidad de emplear elevadas densidades de mallado para poder reproducir el efecto de las distintas preparaciones de filo y la relevancia de establecer redondeos de filo adecuados a cada proceso de mecanizado. El incremento del radio de la arista de corte incrementa la robustez de la herramienta frente a determinados tipos de desgaste como el astillado, pero provoca mayores esfuerzos de corte y temperaturas que aceleran otros mecanismos de desgaste como la abrasión o la difusión. Este efecto es especialmente relevante en los procesos de mecanizado de titanio debido a que este material se vuelve extremadamente reactivo por encima de aproximadamente 600ºC.

This work presents an approach to the detection of catastrophic tool breakage in automatic drilling processes that take place during the assembly phase of aeronautical structural components. During the drilling phase, fuselage components are arranged in hybrid stacks, including carbon fiber composite and titanium alloy. Machining conditions vary along each drilling operation depending on the material and number of components, their thicknesses, cutting parameters, the cooling and/or lubrication system, and workpiece clamping. In the machining process of these hybrid stacks, the level of complexity can lead to critical conditions that result in catastrophic tool failure. This scenario is particularly problematic due to the cost and time involved, especially in automatic processes. To detect the moment when these events occur in real-time, a detection method based on the time-frequency domain analysis of the main spindle power consumption signals is proposed. Specifically, the feasibility of using the Haar, Daubechies, Symlet and Coiflet discrete wavelet transforms with different decomposition levels is studied to detect breakages considering signals corresponding to a 4.6 mm diameter tool in the production system. Keywords: Discrete Wavelet Transform, Multiresolution Analysis, Time-frequency analysis, Tool breakage detection, Drilling monitoring, CFRP/Ti6Al4V hybrid stacks, Industry 4.0

Durante décadas, un buen maquinista podía detectar que una herramienta estaba a punto de romperse con solo escuchar el sonido del torno. Hoy, esa intuición tiene un nuevo aliado: sensores, datos e inteligencia artificial capaces de detectar señales invisibles y anticiparse a los problemas antes de que lleguen.