A. Gisario

Production of open cell aluminum foams by using the dissolution and sintering process (DSP)

The manufacture of open cell metal foams by dissolution and sintering process (DSP) is the matter of the present work. Aluminum foams were produced by mixing together carbamide particles with different mesh sizes (i.e., space-holder) and very fine aluminum powders. Attention was first paid at understanding the leading phenomena of the different stages the manufacturing process gets through: Compaction of the main constituents, space-holder dissolution, and aluminum powders sintering. Then, experimental tests were performed to analyze the influence of several process parameters, namely, carbamide grain size, carbamide wt %, compaction pressure, and compaction speed on the overall mechanical performance of the aluminum foams. Meaningfulness of each operational parameter was assessed by analysis of variance. Metal foams were found to be particularly sensitive to changes in compaction pressure, exhibiting their best performances for values not higher than 400 MPa. Neural network solutions were used to model the DSP. Radial basis function (RBF) neural network trained with back propagation algorithm was found to be the fittest model. Genetic algorithm (GA) was developed to improve the capability of the RBF network in modeling the available experimental data, leading to very low overall errors. Accordingly, RBF network with GA forms the basis for the development of an accurate and versatile prediction model of the DSP, hence becoming a useful support tool for the purposes of process automation and control.

Hybrid forming process of AA 6108 T4 thin sheets: modelling by neural network solutions

Abstract The highly non-linear deformation processes occurring in most dynamic sheet metal forming operations cause large amounts of elastic strain energy to be stored in the formed material and massive related springback phenomena. Therefore, this paper investigates how effective a laser source is in reducing the extent of springback in mechanical contact forming operations. The hybrid forming process investigated was composed of using a high-power diode laser to induce local heating of mechanically bent AA 6108 T4 thin sheets in order to minimize the extent of the springback. In particular, experiments were carried out to assess the influence of the leading process parameters such as laser source power, scan speed, and starting elastic deformation of the mechanically bent sheets. It was found that the trends in the experimental response of residual deflection were always consistent with the operating parameters. Artificial intelligence techniques were then used to model the hybrid forming process. The extent of the springback in the hybrid forming process of AA 6108 T4 thin sheets was predicted by using different neural network models and training algorithms. Lastly, the reliability of the best neural network solutions was checked by comparing these solutions with experimental results and by developing an ad hoc first approximation technical model.

Dissimilar joining of transparent Poly(ethylene terephthalate) to aluminum 7075 sheets using a diode laser

Laser welding has improved the manufacturing productivity and made a great opportunity over conventional joining methods. Producing hybrid metal-polymer components is drawing more attention in terms of their aptitude specifically in the aerospace and automotive industries. The joining of a hybrid metal and a polymer can be troublesome due to some drawbacks in chemical and physical properties or incompatible structures. Diverse techniques are applied for joining dissimilar materials, specifically polymers and metals with the purpose of achieving high flexibility. Laser welding is an effective technology to join dissimilar materials with considerable advantages such as flexibility, low environmental impacts, noncontact, high speed, and accuracy. In fact, the main challenge for manufacturers is still on how to choose the input process parameters to get the best joint performance. This paper investigates an experimental study of dissimilar welding of transparent Poly(ethylene terephthalate) to aluminum 7075 sheets by a diode laser. Laser joining parameters play a crucial role in determining the quality of joining between PET films and aluminum plates. In the present work, laser power and scan speed were considered as operational parameters, which have a significant influence on the quality of the joint zone. Laser transmission joining was optimized using response methodology for achieving good joint strength with minimal barriers.Laser welding has improved the manufacturing productivity and made a great opportunity over conventional joining methods. Producing hybrid metal-polymer components is drawing more attention in terms of their aptitude specifically in the aerospace and automotive industries. The joining of a hybrid metal and a polymer can be troublesome due to some drawbacks in chemical and physical properties or incompatible structures. Diverse techniques are applied for joining dissimilar materials, specifically polymers and metals with the purpose of achieving high flexibility. Laser welding is an effective technology to join dissimilar materials with considerable advantages such as flexibility, low environmental impacts, noncontact, high speed, and accuracy. In fact, the main challenge for manufacturers is still on how to choose the input process parameters to get the best joint performance. This paper investigates an experimental study of dissimilar welding of transparent Poly(ethylene terephthalate) to aluminum 7075 s...

Modelling of Fluidized Bed Degreasing (FBD) process by ANNs

This paper is focused on a relatively novel eco-efficient degreasing technique, namely Fluidized Bed Degreasing (FBD), based on a fluidised bed of hard particles. An experimental campaign was aimed to investigate the relationship between FBD operational parameters and degreasing effectiveness. Consistent trends of residual oil according to FBD process parameters were found and both a related power dissipation analytical model and a neural network were developed and verified by comparison with experiments. The Multi-Layer Perceptron (MLP) neural network, trained with Back-Propagation (BP) algorithm, gave the best performance. Finally, Genetic Algorithms (GAs) were used to improve the predicting capability of the neural network solution. In detail, an experimental plan was performed to check the generalisation capability of the neural network model with GA.

The mechanisms of material removal in the fluidized bed machining of polyvinyl chloride substrates

In this paper, the mechanisms of material removal during the fluidized bed machining (FBM) of polymeric substrates are analyzed. Cylindrical components composed of polyvinyl chloride (PVC) were exposed to the impact of abrasives while rotating at high speed within a fluidization column. The interaction between the Al2O3 abrasive media and the PVC surfaces was studied to identify the effect of the main process parameters, such as the machining time, the abrasive mesh size, and the rotational speed. The change in the surface morphology as a function of the process parameters was evaluated using field emission gun—scanning electron microscopy (FEG-SEM) and contact gauge profilometry. An improvement in the finishing of the processed surfaces was achieved, and the related mechanisms were identified. The roles of the impact speed and the contact conditions between the abrading particles and the substrate were also investigated.

Advances in laser processing of Metal Matrix Composites (MMCS)

The present work deals with the application of a High Power Diode Laser (HPDL) to improve the mechanical properties of Al2O3 particle-reinforced Aluminum Matrix Composites (AMCs). An experimental plan in which laser power and interaction time were individually varied was carried out to evaluate the influence of both process parameters on the surface performance of the AMCs. In this respect, the evolution of their surface morphology was assessed by contact-gauge profilometry. Further samples were, then, analyzed by FIMEC micro-indentation test, depth-sensing load controlled scratch and wear test. Experimental findings show that mechanical and tribological proprieties of the laser treated substrates can be considerably improved, although in an operating range of process parameters rather narrow. Finally, an analytical model was proposed to correlate the wear performance of the AMCs investigated to their morphological and mechanical properties.The present work deals with the application of a High Power Diode Laser (HPDL) to improve the mechanical properties of Al2O3 particle-reinforced Aluminum Matrix Composites (AMCs). An experimental plan in which laser power and interaction time were individually varied was carried out to evaluate the influence of both process parameters on the surface performance of the AMCs. In this respect, the evolution of their surface morphology was assessed by contact-gauge profilometry. Further samples were, then, analyzed by FIMEC micro-indentation test, depth-sensing load controlled scratch and wear test. Experimental findings show that mechanical and tribological proprieties of the laser treated substrates can be considerably improved, although in an operating range of process parameters rather narrow. Finally, an analytical model was proposed to correlate the wear performance of the AMCs investigated to their morphological and mechanical properties.

On the use of Fluidised Bed Coating (FBC) to deposit thin Al 2O 3 films onto metal substrates

Fluidised Bed Coating (FBC) is a viable and low-cost technique to apply, at ambient temperature, thin adherent ceramic coatings onto metal and non metal substrates. Al2O3 films, by virtue of its special thermo-mechanical, chemical, electrical and optical properties, belong to a class of ceramic coatings of particular interest in several manufacturing processes. In this respect, the present paper reviews selected applications in manufacturing of Al2O3 coated aluminium substrates. In particular, the use of fluidised bed deposited thin Al2O3 films has been reported as surface overlay coatings to improve the fatigue behaviour of aluminium components, as absorption and thermal barrier coatings in sheet laser forming and, finally, as anti-wear protective coatings.