Polyamide 6-Aluminum Assembly Enhanced by Laser Microstructuring

The presented work’s aim is the application of low-power laser treatment for the enhancement of interfacial micromechanical adhesion between polyamide 6 (filled with glass fiber) and aluminum. A fiber laser beam was used to prepare micro-patterns on aluminum sheets. The micro-structuring was conducted in the regime of 50, 100, 200 and 300 mm/s laser beam speeds, for both sides. The joining process was realized in an injection molding process. Metallic inserts were surface engraved and overmolded in one-side and two-side configurations. A lap shear test was used to examine the strength of the joints. Engraved metallic surfaces and adequate imprints on polyamide side were checked by optical microscope with motorized stages, and roughness parameters were also determined. Microscopic observations made it possible to describe the grooves’ shape and to conclude that a huge recast melt was formed when the lowest laser beam speed was applied; thus, the roughness parameter Ra reached the highest value of 16.8 μm (compared to 3.5 μm obtained for the fastest laser speed). The maximum shear force was detected for a sample prepared with the lowest scanning speed (one-sides joints), and it was 883 N, while for two-sided joints, the ultimate force was 1410 N (for a scanning speed of 200 mm/s).

Design and manufacturing of an innovative rolling ball tool: A step forward towards the development of SPIF process

Incremental sheet forming (ISF) is an innovative forming technology which is widely used in various sectors of mechanical production. This is particularly useful for rapid prototyping and limited batch without a specific die. A new class of this method is single-point incremental forming (SPIF). This paper presents a comprehensive experimental investigation on the SPIF of Aluminum sheets, and, in particular, the influence of the forming tool is taken into account. A new rolling ball tool is designed to follow this, and the formability of the Aluminum sheets under the SPIF procedure is investigated for both new and conventional tools. Moreover, a number of important process parameters such as the feed rate, forming force, and surface roughness are considered in the experiments’ design. Finally, the optimal conditions in achieving a developed SPIF procedure in terms of the mentioned factors are reported and discussed. The findings of this work suggest that the surface quality after the forming process can be enhanced by 55% when using the new designed tool, while the forming force is reduced by 38% at the same time.

Thermal Parametric Study of Butt Joints Using Friction Stir Welding

The purpose of this study is to look at the mechanical and microstructural properties of dissimilar 2024 and 7075 aluminum sheets that have been welded together using friction stir welding (FSW). The two sheets, which were aligned with perpendicular rolling directions, were successfully fused; the welded sheets were then tested under strain at room temperature to determine the mechanical response to the materials for the parents Since the fatigue behavior of light metals is known, the fatigue endurance (S–N) curves of welded joints have been achieved. A resonant electro-mechanical testing machine load is the best performance indicator for a significant part of industrial applications; welded sheets is the best performance indicator for a big part of industrial applications. At a load frequency of around 75 Hz, a constant load ratio R = 0.1 was employed. The microstructure that formed as a result of the FSW Optical and scanning electron microscopy have been used to investigate the process, both on ‘as welded’ specimens and on tested specimens following a rupture

Waste Aluminum Application as Energy Valorization for Hydrogen Fuel Cells for Mobile Low Power Machines Applications

This article proposes a new model of power supply for mobile low power machines applications, between 10 W and 30 W, such as radio-controlled (RC) electric cars. This power supply is based on general hydrogen from residual aluminum and water with NaOH, so it is proposed energy valorization of aluminum waste. In the present research, a theoretical model allows us to predict the requested aluminum surface and the required flow of hydrogen has been developed, also considering, in addition to the geometry and purity of the material, two key variables as the temperature and the molarity of the alkaline solution used in the hydrogen production process. Focusing on hydrogen production, isopropyl alcohol plays a key role in the reactor’s fuel cell vehicle as it filters out NaOH particles and maintains a constant flow of hydrogen for the operation of the machine, keeping the reactor temperature controlled. Finally, a comparison of the theoretical and experimental data has been used to validate the developed model using aluminum sheets from ring cans to generate hydrogen, which will be used as a source of hydrogen in a power fuel cell of an RC car. Finally, the manuscript shows the parts of the vehicle’s powertrain, its behavior, and mode of operation.

Comparative Study of Popular Deep Learning Models for Machining Roughness Classification Using Sound and Force Signals

This study compared popular Deep Learning (DL) architectures to classify machining surface roughness using sound and force data. The DL architectures considered in this study include Multi-Layer Perceptron (MLP), Convolution Neural Network (CNN), Long Short-Term Memory (LSTM), and transformer. The classification was performed on the sound and force data generated during machining aluminum sheets for different levels of spindle speed, feed rate, depth of cut, and end-mill diameter, and it was trained on 30 s machining data (10–40 s) of the machining experiments. Since a raw audio waveform is seldom used in DL models, Mel-Spectrogram and Mel Frequency Cepstral Coefficients (MFCCs) audio feature extraction techniques were used in the DL models. The results of DL models were compared for the training–validation accuracy, training epochs, and training parameters of each model. Although the roughness classification by all the DL models was satisfactory (except for CNN with Mel-Spectrogram), the transformer-based modes had the highest training (>96%) and validation accuracies (≈90%). The CNN model with Mel-Spectrogram exhibited the worst training and inference accuracy, which is influenced by limited training data. Confusion matrices were plotted to observe the classification accuracy visually. The confusion matrices showed that the transformer model trained on Mel-Spectrogram and the transformer model trained on MFCCs correctly predicted 366 (or 91.5%) and 371 (or 92.7%) out of 400 test samples. This study also highlights the suitability and superiority of the transformer model for time series sound and force data and over other DL models.

Corrosion Protection of Nano-Silica Powder Coatingon Artificial Seawater

Sea water resources are extensive and can be used to extinguish fires, but their corrosiveness is a major problem. Using the method of electrochemical workstation, the electrochemical corrosion behavior of aluminum sheet in artificial sea water solution and silica-coated artificial seawater was studied; by analyzing the surface morphology, polarization curve and electrochemical impedance spectroscopy, the electrochemical corrosion behavior of aluminum sheets under different immersion times and different immersion media is obtained. The conclusion is that the coating of nanosilica powder has a certain corrosion protection effect on artificial seawater.

Microstructure and Mechanical Performances Analyses on Probeless Friction Stir Spot Welds of AA6061-T6 Aluminum Sheets

Probeless friction stir spot welding (PFSSW) is a variation of conventional friction stir spot welding (CFSSW), which solves the keyhole defect in CFSSW welds. In this work, four types of probeless tools were designed based on helix and spiral feature: small curvature helix (involute tool, IT), large curvature helix (archimedes tool, AT), spiral line (scroll tool, ST) and no feature (flat tool, FT). AA6061-T6 sheets with a thickness of 1.5 mm were welded using the designed probeless welding tools. The effect of tool shapes on the microstructure and mechanical properties of friction stir spot welded AA 6061-T6 aluminum alloy sheets was investigated using different rotational speeds, plunging depths and dwell times. The Taguchi method was utilized to obtain the optimal welding parameter combination for the four tools. And, the tensile-shear mechanical properties of FSSW specimens were characterized under the optimal parameters. The results show that a basin-shaped profile appeared in the weld metallography using the groove tools. The tensile shear failure load (TSFL) of IT (~6.97 kN) was higher than that of ST (~6.49 kN), AT (~6.19 kN) and FT (~5.67 kN), sequentially. Three different fracture modes, interfacial fracture, plug fracture and mixed-mode fracture were observed in the tensile-shear tests of weld specimens.

MANUFACTURING THINNED FRICTION-STIR WELDED 1050 ALUMINUM BY POST ROLLING: MICROSTRUCTURE AND MECHANICAL PROPERTIES

One of the friction-stir welding (FSW) limitations is joining thin sheets in sheet-metal manufacturing. To solve this limitation, thicker sheets can be welded with FSW and then rolled to a thinner thickness. This can improve the mechanical properties and save the weld zone soundly. In this work, 3-mm aluminum sheets were joined with FSW. The microstructure and mechanical properties of the samples were assessed at various rotational speeds (w) and travel speeds (v). Then, the welded samples were cold worked (CW) by rolling them at different percentages so that the samples were 2 mm and 1 mm thick. The effects of welding and post rolling on the mechanical properties and a failure analysis were deliberated. It was shown that welding reduces the transverse ultimate tensile strength (UTS) of FSWed samples by up to 29 % compared to the UTS of the base metal (BM), while rolling FSWed samples increased the UTS of the cold-worked FSWed samples by up to 94.7 % in comparison to the UTS of FSWed samples. Also, during the tensile test of the specimens FSWed at a lower travel speed, a fracture occurred at the stir zone (SZ)/thermo-mechanically affected zone (TMAZ) interface, on the advancing part; however, at a higher travel speed, it occurred at the interface of the heat-affected zone (HAZ) and TMAZ, on the retreating part. Moreover, during the tensile test of the cold-worked FSWed samples, the failure took place at the HAZ and the interface of the SZ and TMAZ, respectively. The UTS was risen by increasing the cold work. The UTS of a specimen FSWed at 50 mm/min and 1200 min–1 went up from 76 MPa to 124 MPa due to 33-% cold work and to 148 MPa due to 66-% cold work; meanwhile, the fracture occurred at the SZ/TMAZ interface or TMAZ of most of the post-rolled FSWed samples.