Surface Quality and Free Energy Evaluation of s275 Steel by Shot Blasting, Abrasive Water Jet Texturing and Laser Surface Texturing

Surface modification by different technologies prior to joining operations or improving tribological properties is a point of great interest. Improving surface activation by increasing the roughness of the metal is a relationship that is becoming more defined. In turn, an increase in surface wettability by evaluating contact angles indicates surface activation by obtaining a high surface free energy. Technologies such as shot blasting and laser surface texturing (LST) have generated several scientific studies where they have identified the influence of parameters on the formation of rough surfaces with defined patterns. However, the application of abrasive water jet texturing (AWJT) has been little studied as an alternative. This article compares these technologies in the texturing of a carbon steel s275 in order to identify the relationship between surface quality and surface activation. It has been determined that AWJT produces the highest Rt values close to 64 mu m with a cross feed of 0.45 mm and a traverse speed of 5000 mm/min. Furthermore, LST obtains the best values of free surface energy by combining a power of 20 W with a frequency of 20 kHz and a sweeping speed of 10 mm/s. Finally, contour diagrams have been obtained which relate these variables to the texturing parameter

On the Surface Quality of CFRTP/Steel Hybrid Structures Machined by AWJM

The joining of dissimilar materials in a hybrid structure is a line of research of great interest at present. Nevertheless, the machining of materials with different machinability requires specific processes capable of minimizing defectology in both materials and achieving a correct surface finish in terms of functional performance. In this article, abrasive water jet machining of a hybrid carbon fiber-reinforced thermoplastics (CFRTP)/Steel structure and the generated surface finish are studied. A parametric study in two stacking configurations (CFRTP/Steel and Steel/CFRTP) has been established in order to determine the range of cutting parameters that generates the lowest values in terms of arithmetic mean roughness (Ra) and maximum profile height (Rz). The percentage contribution of each cutting parameter has been identified through an ANOVA analysis for each material and stacking configuration. A combination of 420 MPa hydraulic pressure with an abrasive mass flow of 385 g/min and a travel speed of 50 mm/min offers the lowestRaandRzvalues in the CFRTP/Steel configuration. The stacking order is a determining factor, obtaining a better surface quality in a CFRTP/Steel stack. Finally, a series of contour diagrams relating surface quality to machining conditions have been obtained

Análisis, evaluación y propuesta de mejora del rendimiento del mecanizado de materiales compuestos de naturaleza termoplástica

En este trabajo se ha analizado el comportamiento de materiales compuestos de resina de poliuretano termoplástico reforzada con fibras de carbono (CFRTP) frente a diversos procesos de acabado (postprocesado) sustractivos, convencionales y no convencionales, eficaz para caracterizar el diseño de productos en piezas primerias y secundarias y aportar la calidad necesaria. El interés de esta investigación radica en la tendencia ascendente al uso de los materiales compuestos de matriz polimérica, entre los cuales se encuentra el poliuretano termoplástico. Las resinas termoplásticas presentan una serie de ventajas respecto a las termoestables, entre ellas su facilidad de procesamiento y su reciclaje. Esto ha permitido que el conformado de esta resina junta a fibras de carbono lleve a los CFRTPs a presentarse como una alternativa viable a los materiales compuestos más empleados en la industria.No obstante, el peso principal de este trabajo recae en el postprocesado de dichos materiales, entendiendo como postproceso aquellas operaciones secundarias capaces de obtener la geometría final, acabados y tolerancias requeridas. En esta ocasión, tras reiteradas revisiones de la literatura científica y experimentos llevados a cabo, se ha desarrollado el análisis del CFRTP en cuestión, frente a las tecnologías de fresado y chorro de agua con abrasivo