Additive manufacturing of metallic components – Process, structure and properties

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

Additive manufacturing of metals

Consolidation phenomena in laser and powder-bed based layered manufacturing

Welding Metallurgy of

This paper explores the effects of the scanning strategy and several fundamental process parameters, like laser power, scanning speed and frequency, on the quality of a carbon-fiber reinforced polymer (CFRP) component processed by laser scarfing. Specifically, the composite consisted of an epoxy resin matrix with woven carbon fibers reinforced with copper wires. Particular attention was paid to the ablation depth and to the quality of the scarfing area. The integrity of the copper fibers is intrinsically correlated to the functionality of the material after the scarfing process, which was assessed in the paper.

On the laser scarfing of epoxy resin matrix composite with copper reinforcement

The implementation of iterative learning control algorithms on a real mechanical manipulator is discussed. The algorithms rely on off-line estimates of generalized velocity and acceleration errors, and on their boundedness in presence of noisy measures. A class of robust estimators is introduced, based on the theory of the spectral analysis of descriptor systems. The use of these estimators in the implementation of learning control algorithms has been tested on a prototypal manipulator at DIST and experimental results are reported. >

http://ieeexplore.ieee.org/iel4/564/6178/00240680.pdf

Experimental experience on iterative learning control implemented on a prototypal manipulator

In this paper, we describe a quadrotor able to land autonomously on a moving platform by employing on-board sensors. The full pose of the platform is estimated using a vision system. Furthermore, an ultrasonic sensor is used to compute the relative vertical position and velocity of the platform w.r.t. the quadrotor. This redundant information is used to achieve greater robustness during the final landing phase. The landing algorithm is presented and an overview of the overall architecture is provided. Software-in-the-loop simulations have been performed to evaluate the performance and to analyse in a safe way the entire landing procedure. We have finally tested our landing system in a real world environment using a customized quadrotor. Results of the landing procedure performed with real quadrotor are presented.

Visual Servoed Autonomous Landing on a Surface Vessel

The layers fabrication technique, known as Selective Laser Sintering SLS, is widely used. A basic investigation on its application in the field of the fabrication of transitory molds in the foundry industry is the object of this work. In fact, the Selective Laser Sintering (SLS) of pre­covered foundry sands allows the aggregation of adjacent particles with the possibility to realize molds and cores not obtainable with conventional methods.Since LaserCron is widely used for sand casting (by EOS) with SLS, the authors investigated its CO2 laser behavior. The laser effect on sand has been evaluated in terms of sintering thickness and deformations of layers along the z-axis. A full factorial approach has been used in order to evaluate the effects of three controllable factors, i.e. laser power, scan speed, scan spacing, and their interactions, on the layers adhesion, surface quality, and accuracy of the obtained product. Response surface methodology and Analysis of Variance have been used to evaluate SLS process performance, in terms of process parameter evaluation and optimization.The layers fabrication technique, known as Selective Laser Sintering SLS, is widely used. A basic investigation on its application in the field of the fabrication of transitory molds in the foundry industry is the object of this work. In fact, the Selective Laser Sintering (SLS) of pre­covered foundry sands allows the aggregation of adjacent particles with the possibility to realize molds and cores not obtainable with conventional methods.Since LaserCron is widely used for sand casting (by EOS) with SLS, the authors investigated its CO2 laser behavior. The laser effect on sand has been evaluated in terms of sintering thickness and deformations of layers along the z-axis. A full factorial approach has been used in order to evaluate the effects of three controllable factors, i.e. laser power, scan speed, scan spacing, and their interactions, on the layers adhesion, surface quality, and accuracy of the obtained product. Response surface methodology and Analysis of Variance have been used to evaluate SLS proc...

Preliminary experience with sand casting applications of rapid prototyping by selective laser sintering (SLS)

In this paper a study on some aspects of the weldability of a copper aluminum alloy to an austenitic stainless steel through a MIG-Laser combined heat source is presented.In particular the effect of the heat source position over the welding sheets on the interface between the two metals was investigated.Using a steel feed wire the combined heat source was positioned in several working positions. Firstly, the axis connecting the torch to the laser beam was set parallel to the seam in the laser leading layout.Alternatively, the axis was rotated respect to the seam so the filler material dropped on the steel or the aluminum side. In the latter case an aluminum alloy feed wire was used.The different layouts had some goals to reach. In the first position it was aimed to maximize the welding penetration and evaluate the brittle intermetallic phases that form in different material joint. The second position aimed to limit the stirring effect of the two alloys and in turn the formation of the brittle phases by fu...

Giuseppe Casalino

Papers

On the laser scarfing of epoxy resin matrix composite with copper reinforcement

Experimental experience on iterative learning control implemented on a prototypal manipulator

Visual Servoed Autonomous Landing on a Surface Vessel

Preliminary experience with sand casting applications of rapid prototyping by selective laser sintering (SLS)

MIG-laser combined welding of aluminum alloy to 304 stainless steel