Build orientation effect on Ti6Al4V thin-wall topography by electron beam powder bed fusion

Additive Manufacturing is a key enabling technology for Industry 4.0 and the Green Deal, allowing more efficient resources exploitation while providing innovative design to critical components. Electron Beam Powder Bed Fusion (EB-PBF) is an edge technology for many sectors, i.e. aerospace, medical, and automotive. The control of the surface finish by surface topography measurements is essential to engineer surface functional properties, whose specifications are application specific. This works investigates the effect of thin-wall orientation and surface inclination on the topography, described by areal field and feature parameters, to provide designers with a useful tool in the early stage of product development and tolerance specification and verificatio

Analysis of residual plastic deformation of blanked sheets out of automotive aluminium alloys through hardness map

Reducing overall vehicle weight is essential to reduce fuel consumption and pollutant emission and to improve noise, vibration, and harshness (NVH) performances. The substitution with lighter alloys can involve the grand majority of vehicle components, depending on the market sector. In several applications, e.g., chassis, pulleys, and viscodampers, metal sheets are formed in several steps, each of whom work-hardens the material reducing the available residual plasticity. Typically, the process is designed via FEM, whose results are affected by the initial conditions, often neglected, and is performed on pre-processed materials from suppliers. In this regard, correctly simulating the first step of the process is critical. However, the related initial conditions, in terms of residual stress and strain induced by former preliminary operations, are often neglected. This work proposes a quick and economical experimental procedure based on a hardness map to estimate initial conditions and to validate FEM results. The procedure allows evaluating the material's residual plasticity, which is necessary to process engineers to design following manufacturing steps. The approach is demonstrated on an industrially relevant case study, i.e., the blanking of an AA 5754, in use for water pump pulleys

Development of a low-cost monitoring system for open 3d printing

3D printers for Rapid Prototyping and Additive Manufacturing have been widely accepted by large and small-scale industries or by many hobbyists. Due to its nature of layer by layer addition of material, identifying defects between the layers can be a crucial strategy to determine the quality of a 3D printed product by carefully monitoring the layerwise process during part building. This kind of approach gives an advantage in the applications where 3D printing of products requires high customization without compromise on part quality. In this work, a low-cost camera is installed in an open 3D printer, and computer vision algorithms are used to implement an in-situ monitoring system. The defects can be evaluated by comparing the printed layer to the deposition path of the open ISO G-code. The G-code printing file is modified to introduce the image capture step after each layer. The value of the area of missing or exceeding material is returned to the user with the corresponding images. A decision can be made to abort the job in case of important defects to avoid unnecessary waste in material, time, and costs

Benchmarking analysis of digital light processing resins in terms of dimensional accuracy and geometric tolerances

Additive Manufacturing (AM) is a groundbreaking fabrication technology that is revolutionizing traditional manufacturing processes. Generally, following a layer-by-layer approach, in AM the final shape of the product is built through the progressive deposition of one or more materials. The most common extrusion-based AM technique for thermoplastic polymers is Fused Filament Fabrication (FFF), whilst for photopolymer resins, Digital Light Processing (DLP) and Stereolithography (SLA) are widely used. In the last years, DLP has spread rapidly, due to its low average cost and simple use. Moreover, a lower layer thickness can be used in DLP if compared to the FFF process. Therefore, hobbyists or amateur end users and many companies use DLP to achieve high dimensional accuracy and smooth surfaces for small products. This work aims to evaluate the performance of three different DLP resins in terms of dimensional and geometrical accuracy. A benchmarking activity is carried out using a Rover printer by Sharebot to produce replicas of a reference part using Sharebot resins. After production, the replicas were inspected using a Coordinate Measuring Machine (CMM) for comparing the dimensional accuracy of the geometric features according to ISO IT grades and tolerances of the GD&T system. The results of this study are also compared with previous works from the literature in the conclusions

Ti-6Al-4V lattice structures produced by EBM: Heat treatment and mechanical properties

Additive manufacturing (AM) processes allow producing the complex components in a layerwise fashion. The complexity includes the design of lighter and stronger components by using lattice structures that can be quickly realized through AM technologies. However, the mechanical behaviour of lattice structures is not completely known, especially in the post-treated state. Thus, this work aims to explore the effect of post-treatment on the compressive strength of specimens with lattice structures. The samples are produced using Ti-6Al-4V powder processed by Electron Beam Melting (EBM). The outcomes of this work confirm the correlation between the heat treatment and final mechanical properties

Reverse Engineering approach for a joystick handgrip re-styling with ergonomic features

Ergonomics plays a more and more important role in product development, ensuring a better quality of life and work and also contributing to enrich the product image. If the importance of an ergonomic design is commonly recognized, no stated procedures for the development of an ergonomic product are still available. This is probably due to the fact that ergonomics is a qualitative subjective characteristic, that can’t be reduced to a list ofspecifications. In agreement with the opinion that a product can be defined ergonomic only in reference to a precise target of users and for a definite application [1], this paper regards aninnovative user-based procedure for the re-styling of a commercial handgrip. The proposed procedure, combining traditional modeling and Time Compression techniques, guarantees the time- and cost-saving development of a product ensuring comfort of use and minimizing pressure concentrations on the user’s hand [2] that can be defined ergonomic since it directly derives from users’ physical characteristics