Carmine Lucignano

Artificial neural networks to optimize the extrusion of an aluminium alloy

Extrusion of aluminium alloys is a complex process which depends on the characteristics of the material and on the process parameters (initial billet temperature, extrusion ratio, friction at the interfaces, die geometry etc.). The temperature profile at the die exit, largely influences microstructure, mechanical properties, and surface quality of an extruded product, consequently it is the most important parameter for controlling the process. In turn the temperature profile depends on other process variables whose right choice is fundamental to avoid surface damage of the extruded product. In the present work, two neural networks were implemented to optimize the aluminium extrusion process determining the temperature profile of an Al 6060 alloy (UNI 9006/1) at the exit of induction heater (ANN1) and at the exit of the die (ANN2). The three-layer neural networks with Levemberg Marquardt algorithm were trained with the experimental data from the industrial process. The temperature profiles, predicted by the neural network, closely agree with experimental values.

Dynamic Mechanical Performances of Polyester–Clay Nanocomposite Thick Films

Dynamic mechanical properties of polyester—montmorillonite nanocomposite thick films, prepared by the in situ intercalative polymerization method, were evaluated in a tensile mode. A fast fabrication procedure was chosen to allow industrial applications. A total time less than 1 h was sufficient to obtain a thick film which could be cut for the specimen preparation. The final films had a thickness of 250 μm and a nano-clay content ranging from 0 to 10 wt%. A differential scanning calorimeter was used to investigate the effect of the clay content on the resin polymerization kinetics whereas tensile tests were performed to make a comparison with dynamic mechanical results. The maximum in the mechanical performances was obtained at the clay content of 1 wt% at which an increase of about 55% for the storage modulus was measured in comparison with the unfilled resin.

Compression Moulding of Rubber Powder from Exhausted Tyres

Compression moulding of rubber powders can be used to produce large products without using any linking agent or virgin material. In this study, medium-size rubber particles (1.2 mm on average) were obtained by mechanical grinding of spent rubbers and used to mould square plates with a length of 150 mm and a weight of 400 g. By changing the moulding pressure, different plate thicknesses were obtained (about 20 mm) as well as different densities and mechanical performances. Moreover, the moulding pressure could be changed to tailor final properties and aesthetics of products. However, a maximum pressure was observed over which it was not possible to increase significantly plate density or strength.

Recycling of Waste Epoxy-Polyester Powders for Foam Production

This paper proposes a new foaming technology (solid-state foaming) to produce structural foams from waste thermosetting resins. The proposed technology is easy and does not require specific and expensive equipments. Solid tablets are produced by cold compaction of resin powder, and foam by heating in an oven. Composite foams can be produced by mixing fillers and resin powder before the cold compaction. In the experiment, an epoxy-polyester (EP-PE) resin powder, deriving from the waste of a manufacturer of domestic appliances, was used with montmorillonite (MMT) particles. Resulting foams with a filler content ranging from 0 to 10 wt% were characterized in terms of physical and mechanical properties (by compression tests). Although the effect of the MMT content seems to be negative for the adopted resin, the feasibility of producing composite foams by recycling waste industrial powders is shown. The properties of the unfilled foams are sufficient for many industrial applications.

Instrumented flat indentation on polyester nanocomposite coatings

Polyester-montmorillonite nanocomposite coatings were prepared by the in situ intercalative polymerisation method and deposited on aluminium (Al) and High-Density Polyethylene (HDPE) substrates by the spin coating method. A fast fabrication procedure was utilised, as 1 h was sufficient to prepare each coated sample. Different coating thicknesses and filler contents were considered for the experimentation. Mechanical tests were carried out on the nanocomposite coatings by macro-indentation with a 2 mm flat punch made of tungsten carbide. An increase in the coating strength was measured up to 3 wt% nanoclay content for both the thicknesses and substrates.

New Technological Solutions for Recycling Spent Tire Rubber

To recycle spent tires, the combination of powder comminution and compression molding of resulting powders (without virgin rubber or linking agent) is an efficient solution to produce rubber components with good mechanical properties. Previous studies showed the feasibility of this recycling technology but new efforts are necessary to increase the rubber part size and complexity as well as to find new industrial applications. In this study, some important technological aspects of direct powder molding have been analyzed for the first time: the ability of giving a complex shape to the rubber part or performing secondary works to improve aesthetics and functions.

The Role of Mixing Time in the Production of Nanocomposite Thermosetting Coatings

In this study, nanocomposite coatings have been produced by mixing unsaturated polyester resin with 1 and 5 wt% of montmorillonite (MMT). Nanocomposites were studied as bulk and as coatings to accurately evaluate the combined effect of mixing time and MMT content on final performances of the mixtures. Rheological analyses, mechanical and dynamic mechanical tests, tribological tests and scratch tests were performed on samples. Results show the strong effect of the mixing time on the performance of MMT-filled coatings: this effect is never negligible and can overcome the effect of the MMT content.

Production of Tribological Composites by Recycling Dust of Friction Products

Polymeric matrix composites were prepared by mixing a tribological dust in a polyester resin. The dust resulted from the fabrication process of friction products and was initially destined for disposal. Composite specimens were fabricated with different dust content (up to 70wt%) and cured in an oven at 80°C for 30min. Flexure tests and dynamic mechanical analysis (DMA) were carried out together with pin-on-disc tests to quantify mechanical and tribological performances. Flexural modulus and strength generally increased by increasing the filler content as well as the friction coefficient. At the highest values (60—70 wt%), mechanical and tribological properties were damaged by the dust clustering during mixing.

Fatigue strength of hard-chromium-plated handlebars

Prototypes of handlebars for motorcycles were fabricated by rotary bending and hard-chromium electrodeposition. Fatigue tests were carried out on rough handlebars and hard-chromium plated handlebars; the former resisted over 200.000 cycles, the latter failed at about 50.000 cycles. Scanning Electron Microscopy (SEM) allowed one to observe the presence of sub-surface cracks, which probably originated during the tube bending. Moreover numerical simulation permitted one to identify the occurrence of buckling during the bending process. The combination of buckling, cracks and residual stresses from the chromium electrodeposition results in a very poor behaviour of the handlebar under fatigue test.