On the friability of mussel shells as abrasive

The spread of raft-farming of mussels in river estuaries around the world produces about 1.4 million tons of shell waste which mainly ends up in landfills. In addition, the United Nations and the European Union promote the sustainable development goals (SDG) for sustainable food production, which requires adequate waste management to analyse the life cycle and reuse of goods and materials. This work proposes to use mussels shells by-products created by the canning industry as abrasive in the sandblasting process. One of the main characteristic of abrasive grains is the friability, which determines the behaviour of the abrasive in the sandblasting process. Shells need to be prepared before using in sandblasting, a conditioning that involves cleaning, grinding and sieving of shells. The purpose of this work is to examine the friability of mussel shells from two points of view, the effect of the cleaning process and a comparison with a common abrasive material, the garnet. The characterisation of the friability of mussel shells allows to foresee the behaviour as abrasive and to define the most suitable applications. The obtained results reveal that garnet is four times more friable than shells thanks to shells biocomposite nature. This interesting feature enlarges the life of sand in close cycles and foresees a promising future to the new abrasive.This work has been performed within the MIT-Spain INDITEX Sustainability Seed Fund'' student exchange program (Grant n. 208749). The project has been carried out with the collaboration of La Mejillonera'' (San Sebastian), Evlox'' (Bergara, formerly Tavex Europe''),Koopera'' (Mungia), and Washedcolors'' (Famalicao, Portugal). Open Access funding provided by University of Basque CountryUPV/EHU

An Analysis of Electroplated cBN Grinding Wheel Wear and Conditioning during Creep Feed Grinding of Aeronautical Alloys

Cubic boron nitride (cBN), in addition to diamond, is one of the two superabrasives most commonly used for grinding hard materials such as ceramics or difficult-to-cut metal alloys such as nickel-based aeronautical alloys. In the manufacturing process of turbine parts, electroplated cBN wheels are commonly used under creep feed grinding (CFG) conditions for enhancing productivity. This type of wheel is used because of its chemical stability and high thermal conductivity in comparison with diamond, as it maintains its shape longer. However, these wheels only have one abrasive layer, for which wear may lead to vibration and thermal problems. The effect of wear can be partially solved through conditioning the wheel surface. Silicon carbide (SiC) stick conditioning is commonly used in the industry due to its simplicity and good results. Nevertheless, little work has been done on the understanding of this conditioning process for electroplated cBN wheels in terms of wheel topography and later wheel performance during CFG. This work is focused, firstly, on detecting the main wear type and proposing a manner for its measurement and, secondly, on analyzing the effect of the conditioning process in terms of topographical changes and power consumption during grinding before and after conditioning.The authors gratefully acknowledge the funding support received from the Spanish Ministry of Economy and Competitiveness and the FEDER operation program for funding the project "Optimizacion de procesos de acabado para componentes criticos de aerorreactores" (DPI2014-56137-C2-1-R)

Five-Axis Milling of Large Spiral Bevel Gears: Toolpath Definition, Finishing, and Shape Errors

In this paper, a five-axis machining process is analyzed for large spiral-bevel gears, an interesting process for one-of-kind manufacturing. The work is focused on large sized spiral bevel gears manufacturing using universal multitasking machines or five-axis milling centers. Different machining strategies, toolpath patterns, and parameters are tested for both gear roughing and finishing operations. Machining time, tools' wear, and gear surface are analyzed in order to determine which are the best strategies and parameters for large modulus gear manufacturing on universal machines. The case study results are discussed in the last section, showing the capacity of a universal five-axis milling for this niche. Special attention was paid to the possible affectations of the metal surfaces, since gear durability is very sensitive to thermo-mechanical damage, affected layers, and flank gear surface state.Thanks are addressed to the Department of Education, and to the Universities and Research of the Basque Government for their financial support, by means of the ZABALDUZ program. We thank also the UFI in Mechanical Engineering department of the UPV/EHU for its support to this project

Five-Axis Milling of Large Spiral Bevel Gears: Toolpath Definition, Finishing, and Shape Errors

In this paper, a five-axis machining process is analyzed for large spiral-bevel gears, an interesting process for one-of-kind manufacturing. The work is focused on large sized spiral bevel gears manufacturing using universal multitasking machines or five-axis milling centers. Different machining strategies, toolpath patterns, and parameters are tested for both gear roughing and finishing operations. Machining time, tools' wear, and gear surface are analyzed in order to determine which are the best strategies and parameters for large modulus gear manufacturing on universal machines. The case study results are discussed in the last section, showing the capacity of a universal five-axis milling for this niche. Special attention was paid to the possible affectations of the metal surfaces, since gear durability is very sensitive to thermo-mechanical damage, affected layers, and flank gear surface state.Thanks are addressed to the Department of Education, and to the Universities and Research of the Basque Government for their financial support, by means of the ZABALDUZ program. We thank also the UFI in Mechanical Engineering department of the UPV/EHU for its support to this project

Analysis of the Part Distortions for Inconel 718 SLM: A Case Study on the NIST Test Artifact

The present paper evaluates the misalignment and geometry distortion of the standard National Institute of Standards and Technology (NIST) test artifact in Inconel 718 alloy, when several layers with and without supports are employed to manufacture it by the Selective Laser Melting (SLM) process. To this end, a coordinate-measuring machine (CMM) is used to measure the geometrical distortion in each manufacturing configuration, following the same measurement protocol. The results show that the laser path strategy favors a thermal gradient which, consequently, induces geometrical distortions in the part. To prove this hypothesis, a numerical simulation is performed to determine the thermal gradient and the pattern of the residual stresses. It was found that the geometrical distortion certainly depends on the position of the feature position and laser strategy, where thermal cycles and residual thermal stresses had an impact in the end-part geometry, especially if a high strength-to-weight ratio commonly used in aeronautics is present.This work is supported by the Serra Húnter program (Generalitat de Catalunya) reference number [UPC-LE-304 (2018)] and by the Aeronautics Advanced Manufacturing Center (CFAA) in the JANO—Joint action toward digital transformation project framework. Diego Celentano acknowledges Pontificia Universidad Católica de Chile (PUC), Wallonie-Bruxelles International (WBI) and National Council for Scientific and Technological Research CONICYT (FONDECYT Projects No. 3180006 and 1180591) for the financial supports provided for this work

A RE Methodology to achieve Accurate Polygon Models and NURBS Surfaces by Applying Different Data Processing Techniques

The scope of this work is to present a reverse engineering (RE) methodology to achieve accurate polygon models for 3D printing or additive manufacturing (AM) applications, as well as NURBS (Non-Uniform Rational B-Splines) surfaces for advanced machining processes. The accuracy of the 3D models generated by this RE process depends on the data acquisition system, the scanning conditions and the data processing techniques. To carry out this study, workpieces of different material and geometry were selected, using X-ray computed tomography (XRCT) and a Laser Scanner (LS) as data acquisition systems for scanning purposes. Once this is done, this work focuses on the data processing step in order to assess the accuracy of applying different processing techniques. Special attention is given to the XRCT data processing step. For that reason, the models generated from the LS point clouds processing step were utilized as a reference to perform the deviation analysis. Nonetheless, the proposed methodology could be applied for both data inputs: 2D cross-sectional images and point clouds. Finally, the target outputs of this data processing chain were evaluated due to their own reverse engineering applications, highlighting the promising future of the proposed methodology.This research was funded by the he Department of Economic Development, Sustainability and Environment of the Basque Government for funding the KK-2020/00094 (INSPECTA) research project and the Spanish Ministry of Science and Innovation for funding the ALASURF project (PID2019-109220RB-I00)

The effect of preforming and infusing bindered and unbindered carbon non-crimp-fabrics on the final quality of composites parts

[EN] Vacuum infusion (VI) is a liquid moulding process used to manufacture fibre-reinforced polymer composite parts. The VI process for non-crimp fabric (NCF) preforms is one of the most promising processes for improving the quality and cost efficiency of traditional processes using prepregs and autoclave curing. An understanding of the preform thickness behaviour in the compaction, wetting, and curing stages is necessary to optimise the overall process and obtain high-performance composite parts. In this study, the influence of the material, preforming, and infusion parameters on the thickness of four different carbon NCF laminates were investigated. The preforming behaviour includes the influence of the NCF composition, such as the presence of an organic binder or the number of compaction steps. Infusion was characterised using dielectric analysis (DEA). The properties of the resulting composites were analysed in terms of the fibre volume fraction (FVF) and porosity, as measured using X-ray computed tomography (CT). The main consequence of the outcome of the present study is that, from a manufacturing point of view, downward through-thickness resin infusion offers benefits in terms of thickness, FVF, and porosity tolerance. In addition, the acquired results allow for the identification of the main settings for an optimised consolidation strategy, which could be used for manufacturing NCF composite parts.The authors acknowledge the Spanish Government (Ministry of Science and Innovation, Centro para el Desarrollo Tecnologico Industrial (CDTI) program) for their financial support. We thank the Aerostructures Competence Center at the CBC, Airbus Defense & Space, for the advice received on the configuration of the infusion systems, and to Ronand Fi-acre of SAERTEX GmbH & Co. KG for supplying the carbon NCF material

Abrasive Disc Performance in Dry-Cutting of Medium-Carbon Steel

Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slabs, or tubes. Thus, the abrasive cutting-off process is applied when requiring precision cutting and productivity at a moderate price. Cut-off tools are discs composed of small abrasive particles embedded in a bonding material, called the binder. This work aims to compare the cutting performance of discs with different composition, in dry cutting of steel bars. To do that, disc wear was measured and disc final topography was digitalized in order to determine both disc surface wear patterns and if the abrasive particles bonding into the binder matrix was affected. In addition, X-Ray inspection gave information about the abrasive grit-binder bonding. Therefore, the method here presented allows identifying discs with a superior abrasive-cutting capability, by combining profilometry and tomography to define micrometrical aspects, grit size, and binder matrix structure. Results led to the conclusion that discs with high grit size and protrusion, high grit retention by bond material, and closer mesh of fiberglass matrix binder were the optimal solution.Authors are grateful to Basque government group IT IT1337-19 and Ministry of Mineco REF DPI2016-74845-R

Super Abrasive Machining of Integral Rotary Components Using Grinding Flank Tools

Manufacturing techniques that are applied to turbomachinery components represent a challenge in the aeronautic sector. These components require high resistant super-alloys in order to satisfy the extreme working conditions they have to support during their useful life. Besides, in the particular case of Integrally Bladed Rotors (IBR), usually present complex geometries that need to be roughed and finished by milling and grinding processes, respectively. In order to improve their manufacturing processes, Super Abrasive Machining (SAM) is presented as a solution because it combines the advantages of the use of grinding tools with milling feed rates. However, this innovative technique usually needed high tool rotary speed and pure cutting oils cooling. These issues implied that SAM technique was not feasible in conventional machining centers. In this work, these matters were tackled and the possibility of using SAM in these five-axis centers with emulsion coolants was achieved. To verify this approach, Inconel 718 single blades with non-ruled surfaces were manufactured with Flank-SAM technique and conventional milling process, analyzing cutting forces, surface roughness, and dimension accuracy in both cases. The results show that SAM implies a suitable, controllable, and predictable process to improve the manufacture of aeronautical critical components, such as IBR.This work is based on TURBO project (DPI2013-46164-C2-1-R) of the Spanish Ministry of Economy and Competitiveness. Also, the authors wish to acknowledge the financial support received from HAZITEK program, from the Department of Economic Development and Infrastructures of the Basque Government and from FEDER founds, related to the project with acronym HEMATEX. Besides, the authors would like to thanks as well to BCAM for its collaboration. Finally, thanks are also addressed to Spanish Project MINECO DPI2016-74845-R and RTC-2014-1861-4

Fabrikazio gehigarriaren iraunkortasun-azterketa: materiala aurreztea eta kontsumo energetikoa murriztea

In modern society, a global awareness of the need to reduce the environmental foot-print arising from the human activity is prevalent. However, it is still necessary to make progress in this matter. In view of this situation, the United Nations set the Sustainable Development Goals in 2015, among which the commitment for the industry, innovation and infrastructure should be further explored. In the same line of thought, Additive Manufacturing offers the possibility to promote a sus-tainable consumption of material and energy. Therefore, an analysis of the advantages provided by this technology is presented hereby, in which its sustainability in comparison with conventional manu-facturing methods is assessed.; Gizakiaren ekintzen ondoriozko aztarna ekologikoaren eragina murriztearen garrantziaren kontzientzia globala hedatuta dago egungo gizartean, baina oraindik beharrezkoa da aurrerapausoak ematea. Egora horren aurrean, Nazio Batuen Erakundeak 2015ean aurkeztutako Garapen Iraunkorrerako Helburuen artean, industriaren eta berrikuntzaren aldeko apustuaren beharrizana azpimarratu behar da. Ildo horretan, fabrikazio gehigarria materialaren erabilera murriztu eta kontsumo energetiko jasangarriaren alde egiteko aukera ezin hobea da. Beraz, teknologia horrek eskaintzen dituen abantailen azterketa gauzatu da artikulu honetan, baina betiere ikuspuntu jasangarri batetik eta ohiko teknologiekin alderatuz