291 research outputs found
Approaches for an energy and resource efficient manufacturing in the aircraft industry
Over the recent years, several studies have pointed out the impact of manufacturing on the environment. Especially machining offers great potential for the conservation of energy, resources and the reuse of raw materials. This article gives an overview on the approaches that are currently under investigation at the Institute of Production Engineering and Machine Tools with the aim of improving these aspects. The approaches cover regrinding methods for worn tools, recycling of titanium chips and process planning for hybrid process chains. In the first part of the article, a novel process chain for the automatic regrinding of cemented carbide tools is presented. It is shown that production costs can be reduced significantly, as well as the required energy for production of carbide tools. In the second part of the article, approaches for the recycling of titanium chips from machining processes are described. The last part focuses on the resource and energy efficiency of process chains that contain additive and subtractive processes
A comparative analysis of ceramic and cemented carbide end mills
Milling of ferrous metals is usually performed by applying cemented carbide tools due to their high hardness, temperature and wear resistance. Recently, ceramic tool materials have been on the rise and enhanced the efficiency in machining. As ceramics are brittle-hard materials, tool manufacturing requires a sound knowledge in order to meet the tool requirements such as sharp cutting edges and wear resistance. In this study, milling tools made of the high performance ceramic SiAlON were compared to tools made from cemented carbide. For both tool materials, the influence of a prepared cutting edge was investigated. Both the tool manufacturing process and the cutting edge preparation processes are presented, followed by the application of those tools within milling experiments. In order to evaluate the efficiency of both tool types, the cutting forces and the cumulative process energy demand were analyzed. Additionally, surface roughness of the machined workpieces and tool wear were examined. It was found that the ceramic tools, although process forces were higher than for cemented carbide tools, exhibited by far lower energy consumption, less tool wear and finally generated lower surface roughness. © 2020, The Author(s)
The critical raw materials in cutting tools for machining applications: a review
A variety of cutting tool materials are used for the contact mode mechanical machining of components under extreme conditions of stress, temperature and/or corrosion, including operations such as drilling, milling turning and so on. These demanding conditions impose a seriously high strain rate (an order of magnitude higher than forming), and this limits the useful life of cutting tools, especially single-point cutting tools. Tungsten carbide is the most popularly used cutting tool material, and unfortunately its main ingredients of W and Co are at high risk in terms of material supply and are listed among critical raw materials (CRMs) for EU, for which sustainable use should be addressed. This paper highlights the evolution and the trend of use of CRMs) in cutting tools for mechanical machining through a timely review. The focus of this review and its motivation was driven by the four following themes: (i) the discussion of newly emerging hybrid machining processes offering performance enhancements and longevity in terms of tool life (laser and cryogenic incorporation); (ii) the development and synthesis of new CRM substitutes to minimise the use of tungsten; (iii) the improvement of the recycling of worn tools; and (iv) the accelerated use of modelling and simulation to design long-lasting tools in the Industry-4.0 framework, circular economy and cyber secure manufacturing. It may be noted that the scope of this paper is not to represent a completely exhaustive document concerning cutting tools for mechanical processing, but to raise awareness and pave the way for innovative thinking on the use of critical materials in mechanical processing tools with the aim of developing smart, timely control strategies and mitigation measures to suppress the use of CRMs
Trends and perspectives in the use of organic acids for critical metal recycling from hard-metal scraps
Hard-metal sector, strategic for the industrial economies, is suffering from the reduced availability and price volatility of its main feedstock: critical W and Co. In 2021, a 73.5 kt W and 9.2 kt Co demand for hard-metal production (65% and 5.3% of global demand, respectively), was recorded. Hard-metal scrap recycling is hence desirable for both environmental and economic reasons. A significant recovery of W and Co from manufacturing by-products and scraps is already good practice in the hard-metal industry (42% for W and 22% for Co). However, there is still a lot to do to meet the technical-economic-environmental sustainability in materials and energy enhancement for pursuing a green economy model. Indeed, Chemical Modification and Direct Recycling, which are the most widely employed industrial approaches, typically involve energy and/or harsh chemicals-intensive treatments which require expensive equipment and skilled workers. In the last decade, research efforts have been spent on implementing alternative materials reclamation processes from hard-metal scraps based on the use of bio-based organic acids with the view to increase the rate and quality of the recycled materials exploiting their peculiar metal complexing action as well as to preserve natural resources and prevent the disposal of potentially toxic/polluting substances. Despite the preliminary stage of the research, organic acids were demonstrated to be powerful but gentle agents for the selective leaching of cobalt from WC-Co-based materials as well as promising agents for WO3 dissolution. Indeed, thanks to their acid and complexing properties, they can stabilize metals in their oxidized form giving soluble products and preventing passivation phenomena. Furthermore, organic acids can be obtained by renewable biomass transformation, limiting the request for high-impact industrial chemicals. Hence they points out key features making them promising for the design of eco-friendly recovery processes. In this context, the different industrial approaches to the recovery and recycling of Hard-metal wastes, with specific reference to the role of bio-derived organic acids in hydro- and solvo-metallurgical processes, will be critically reviewed with the view of opening a discussion on the perspectives of their use in designing circular economy models in HM manufacturing as economically, technically and environmentally sustainable as possible
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Mapping the global flow of tungsten to identify key material efficiency and supply security opportunities
Tungsten is an economically important metal with diverse applications ranging from wear
resistant cutting tools to its use in specialized steels and alloys. Concerns about its supply security
have been raised by various studies in literature, mostly due to trade disputes arising from supply
concentration and exports restrictions in China and its lack of viable substitutes. Although tungsten
material flows have been analysed for specific regions, a global mass flow analysis of tungsten is
still missing in literature and its global supply chain remains opaque for industry outsiders. The
objective of this paper is to create a map of global tungsten flows to highlight and discuss key
material efficiency (i.e. using less of a material to make a product or supply a service, or reducing
the material entering production but ending up in waste) and supply security opportunities along
tungsten‘s supply chain that could be incorporated into the planning and prioritization of future
supply security strategies. The results indicate the existence of various intervention alternatives that could help to broaden the supply base and improve the overall material efficiency of the system. In particular, future policy and research and development (R&D) efforts to improve tungsten‘s material efficiency should focus on minimizing tungsten losses as fine particles during beneficiation and extraction (current global losses estimated at 10–40%), as well as on evaluating alternatives to improve recycling collection systems and technologies, which could lead to 17–45% more tungsten discards being recycled into new products.E. Petavratzi, T.J. Brown and A.G. Gunn publish with the permission of the Executive Director of
the British Geological Survey. David R. Leal-Ayala and Julian M. Allwood were supported by the
UK Engineering and Physical Sciences Research Council (EPSRC) through a Leadership
fellowship (reference EP/G007217/1) and a research grant awarded to the UK Indemand Centre
(reference EP/K011774/1). We thank Michael Dornhofer, Felix Gaul and Markus Ettl from
Wolfram Bergbau und Hütten AG for their generous contributions to the paper.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S0921344915300367
Electrodialytic recovery of tungsten and cobalt from an industrial residue – preliminary assessment
Critical raw materials (CRMs) have a significant importance for key sectors in the European economy. This importance will continue to grow due to the Green Deal, as the sustainable transition to carbon neutrality by 2050 is settled in modern technologies and renewable energies, which are closely linked to a need for many raw materials.
Europe is very highly dependent on imports of most of the raw materials needed by European industries, with a set of CRMs presenting a high level of concentration in particular countries, some of them geopolitically unstable. For this reason, the supply chains security depends largely on efficient management of resources throughout the lifecycle and the commitment to recycling using secondary resources, such as industrial residues. Investing in CRMs' recycling processes and their sustainability is essential to maintain the supply chains.
The present work is the first attempt to study the application of the electrodialytic (ED) process for recovery of two CRMs, tungsten (W) and cobalt (Co), from tungsten carbide (WC-Co) scrap powder resultant from end-of-life cutting tools. ED process consists of the application of a low-level electric current, in the presence of cation and/or anion exchange membranes, which promote the separation between compartments.
In this specific work, acid desorption of W and Co from the matrix was carried out, followed by electromigration and electrodialysis. Eight experiments were carried out during 24h, using ED cells with three (3C) and two (2C) compartments to perform three assessments: the best electrolyte, the best solid:liquid ratio, and the best current intensity. The WC-Co matrix was placed in the central cell compartment in the 3C setup and directly in the anode in a 2C cell. The results show that the 2C cell setup with NaCl 0.02 M as catholyte and citric acid 0.4 M as anolyte, a solid:liquid ratio 1:25, and an initial current intensity of 200 mA presented the highest W (2194 mg; 99.6% of total W solubilized) and Co (558 mg; 81.3% of total Co solubilized) recovery. However, the current intensity was not completely optimized yet and needs further investigation.
This dissertation will contribute to guide future experimental work to optimize the ED conditions for W and Co recovery.As matérias-primas críticas (CRMs) possuem uma importância significativa para setores-chave da economia europeia. Essa importância vai continuar a aumentar com o Pacto Ecológico Europeu, uma vez que a transição sustentável para a neutralidade carbónica em 2050 está assente em tecnologias modernas e energias renováveis, intimamente ligadas a uma grande necessidade de um vasto número de matérias-primas.
A Europa depende largamente das importações da maioria das matérias-primas necessárias às suas indústrias, materiais esses altamente concentrados num conjunto de países específicos, alguns deles geopoliticamente instáveis. Por esse motivo, a segurança das cadeias de abastecimento depende em grande parte da gestão eficiente dos recursos ao longo do seu ciclo de vida e do compromisso com a reciclagem, recorrendo a fontes secundárias como resíduos industriais. Investir nestes processos, bem como a garantir a sua sustentabilidade, é fundamental para assegurar a manutenção das cadeias de abastecimento.
O presente trabalho consiste na primeira tentativa de estudar a aplicação do processo eletrodialítico (ED) para recuperação de duas matérias-primas críticas, tungsténio (W) e cobalto (Co), a partir de um pó de carbeto de tungsténio (WC-Co) macerado, resultante de ferramentas de corte em fim-de-vida. O processo ED consiste na aplicação de uma corrente elétrica de baixa intensidade, na presença de membranas de troca catiónica e/ou aniónica, que promovem a separação entre compartimentos.
Neste trabalho específico, foi realizada uma dessorção ácida de W e Co da matriz sólida, seguida de eletromigração e eletrodiálise. Cada uma de oito experiências foi realizada durante 24h, utilizando células ED com três (3C) e dois (2C) compartimentos com três objetivos: obter o melhor eletrólito, o melhor rácio sólido:líquido e a melhor intensidade de corrente. A matriz de WC-Co foi colocada no compartimento central da célula 3C e diretamente no ânodo na célula 2C. Os resultados mostram que a configuração da célula 2C com NaCl 0.02 M como catolito e ácido cítrico 0.4 M como anolito, um rácio sólido:líquido de 1:25 e uma intensidade de corrente inicial de 200 mA apresentou a maior recuperação de W (2194 mg; 99.6% do total de W solubilizado) e Co (558 mg; 81.3% do total de Co solubilizado). No entanto, a intensidade da corrente ainda não foi completamente otimizada, necessitando de mais investigação.
Esta dissertação contribuirá para futuros trabalhos experimentais com vista a otimizar as condições do processo ED para a recuperação de W e Co
Advanced Powder Metallurgy Technologies
Powder metallurgy is a group of advanced processes used for the synthesis, processing, and shaping of various kinds of materials. Initially inspired by ceramics processing, the methodology comprising the production of a powder and its transformation to a compact solid product has attracted attention since the end of World War II. At present, many technologies are availabe for powder production (e.g., gas atomization of the melt, chemical reduction, milling, and mechanical alloying) and its consolidation (e.g., pressing and sintering, hot isostatic pressing, and spark plasma sintering). The most promising methods can achieve an ultra-fine or nano-grained powder structure, and preserve it during consolidation. Among these methods, mechanical alloying and spark plasma sintering play a key role. This book places special focus on advances in mechanical alloying, spark plasma sintering, and self-propagating high-temperature synthesis methods, as well as on the role of these processes in the development of new materials
Recent developments in sustainable manufacturing of gears: a review
Abstract: Environment awareness is of the utmost importance to all socially responsible manufacturers. To be competitive on a global scale manufacturing needs to be aligned with various strict environmental regulations. The manufacturing industry at large is striving to improve productivity and product quality while maintaining a clean and sustainable environment. This can only be achieved by adopting sustainable techniques of manufacturing which include minimizing the number of manufacturing steps by employing advanced and alternative methods, environment-friendly lubricants and lubrication techniques while machining, reducing wastage, active waste management and minimizing energy consumption etc. Gear manufacturing industries, the major service providers to all other industrial and manufacturing segments are also focusing on to implement the techniques targeting overall sustainability. Some of the recent developments to achieve sustainability in gear manufacturing can be summarized as reducing the use of mineral-based cutting fluids by employing alternative lubrication techniques i.e. minimum quantity lubrication (MQL) and dry machining, material saving, waste reduction, minimizing energy consumption and maintaining economic efficiency by reducing the number of gear manufacturing stages (eliminating the necessity of finishing processes) by utilizing advanced methods such as gear rolling and wire electric-discharge machining (WEDM), and finally increasing productivity by minimizing tool wear at high gear cutting speeds through the use of alternative tool materials and coatings. This paper reviews and amasses the current state of technology for sustainable manufacturing of gears and also recommends ways to improve the productivity and quality while simultaneously ensuring environmental sustainability
Energy Efficiency in Machining of Aircraft Components
High production costs and material removal rates characterize the manufacturing of aircraft components made of titanium. Due to competitive pressure, the manufacturing processes are highly optimized from an economical perspective, whereas environmental aspects are usually not considered. One example is the recycling of titanium chips. Because of process-induced contaminations they do not meet the quality required for recycling in high-grade titanium alloys. Thus the components need to be manufactured from primary material, which leads to a poor energy balance. This paper describes a methodology to increase the recycling rate and energy efficiency of the manufacturing process by investigating the influencing parameters on chip quality of the machining process with the aim to increase the chip quality to a recyclable degree under monetary aspects. The analysis shows that the recycling rate can be significantly increased through dry cutting, which also brings economic benefits.German Federal Ministry for Economic Affairs and Energy (BMWi)/03ET1174
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