Preliminary evaluation of a multipass strategy in abrasive waterjet machining of an alloy UNS A92024.

Abrasive waterjet cutting is a valuable method for removing material without causing thermal damage, making it suitable for machining materials of different thicknesses and minimising waste. However, machining thicker materials requires higher flow rates and pressure, resulting in increased energy consumption and surface defects that increase costs. This study proposes a multi-pass strategy to improve the performance of abrasive waterjet machining. The study aims to investigate the impact of the number of passes on the efficiency of machining a thick UNS A92024 alloy. Surface integrity will be evaluated from two perspectives: macrogeometry (such as machining depth and taper) using image processing, and microgeometry (surface roughness). The study will also analyse the relationship between the number of passes and traverse speed to identify the optimal combination and develop a predictive model to enhance overall process performance.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Study of Abrasive Water Jet Machining as a Texturing Operation for Thin Aluminium Alloy UNS A92024

Surface modification of metallic alloys can create hydrophilic or hydrophobic surfaces that enhance the functional performance of the material. For example, hydrophilic surfaces have improved wettability, which improves mechanical anchorage in adhesive bonding operations. This wettability is directly related to the type of texture created on the surface and the roughness obtained after the surface modification process. This paper presents the use of abrasive water jetting as an optimal technology for the surface modification of metal alloys. A correct combination of high traverse speeds at low hydraulic pressures minimises the power of the water jet and allows for the removal of small layers of material. The erosive nature of the material removal mechanism creates a high surface roughness, which increases its surface activation. In this way, the influence of texturing with and without abrasive has been evaluated, reaching combinations where the absence of abrasive particles can produce surfaces of interest. In the results obtained, the influence of the most relevant texturing parameters between hydraulic pressure, traverse speed, abrasive flow and spacing has been determined. This has allowed a relationship to be established between these variables and surface quality in terms of Sa, Sz and Sk, as well as wettability.Partial funding for open access charge: Universidad de Málaga

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

Free surface energy evaluation in the laser texturing of a carbon steel s275

Currently, the manufacture of hybrid structures of dissimilar materials is generating great interest. These allow to combine mechanical properties of different materials to achieve a higher functional performance. To obtain these structures, different joining technologies are used, especially the use of adhesives. Nevertheless, for the correct application of an adhesive, the surface of the metal to be bonded must be prepared. Laser texturing has become a widely studied technology for this purpose because it allows very defined textures to be obtained. This technology allows to activate the surface and improve the application of the adhesive afterwards. In that sense, hydrophilic surfaces are generated and evaluated by wettability tests to know the surface free energy obtained in the texturing. In order to improve the bonding of dissimilar materials in the form of hybrid structure, a study has been carried out on the laser texturing of a carbon steel S275 and the relationship between the texturing parameters with its surface activation through wettability and surface free energy tests. Thus, the energy density obtained by the combination of power and scanning speed allows the generation of very defined textures that increase the surface activation of the steel. This has made it possible to establish a mathematical relationship between the texturing parameters and the results obtained. © 2022 The Authors

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

Evaluation of geometrical defects in AWJM process of a hybrid CFRTP/Steel structure

The bonding of Carbon Fibre Reinforced ThermoPlastic composites (CFRTP) and steel is of great interest nowadays. Nevertheless, the difference in machinability between dissimilar materials requires a specific machining process. Abrasive water jet machining is a flexible and environmentally friendly technology that can machine dissimilar materials at the same time with good results. However, due to the characteristics of the process and materials, geometrical defects such as taper angle can be caused by the loss of kinetic energy. In this research, the study of the final geometry in abrasive waterjet machining of a hybrid CFRTP/Steel structure. A new methodology for the evaluation of taper angle with high accuracy has been developed through image processing. In addition, the surface quality in terms of Ra and Rz has been assessed. A potential-type trend between taper and hydraulic pressure has been established for both materials. Minimum taper values between 1.5° and 5° have been obtained for both materials and stacking configurations with a combination of a hydraulic pressure of 420 MPa, an abrasive mass flow of 225 g/min and a traverse speed of 50 mm/min. © 2021 The Author(s

Predictive models based on RSM and ANN for roughness and wettability achieved by laser texturing of S275 carbon steel alloy

Laser texturing is increasingly gaining attention in the field of metal alloys due to its ability to improve surface properties, particularly in steel alloys. However, the input parameters of the technology must be carefully controlled to achieve the desired surface roughness. Roughness is critical to the activation of the surface before further bonding operations, and it is often assessed using several parameters such as Ra, Rt, Rz, and Rv. This surface activation affects the properties of the metal alloy in terms of wettability, which has been evaluated by the deposition of ethylene glycol droplets through a contact angle. This allowed a direct relationship to be established between the final roughness, the wettability of the surface and the texturing parameters of the alloy. This raises the interest of being able to predict the behaviour in terms of roughness and wettability for future applications in improving the behaviour of metallic alloys. In this research, a comparative analysis between Response Surface Models (RSM) and predictive models based on Artificial Neural Networks (ANN) has been conducted. The model based on neural networks was able to predict all the output variables with a fit greater than 90%., improving that obtained by RSM. The model obtained by ANN allows a greater adaptability to the variation of results obtained, reaching deviations close to 0.2 μm. The influence of input parameters, in particular power and scanning speed, on the achieved roughness and surface wettability has been figured out by contact angle measurements. This increases its surface activation in terms of wettability. Superhydrophilic surfaces were achieved by setting the power to 20 W and scanning speed to ten mm/s. In contrast, a power of 5 W and a scanning speed of 100 mm/s reduced the roughness values.Funding for open access charge: Universidad de Málaga / CBU