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ABSTRACT
The role of metal forming in a world with zero emissions
Most countries of the world have now agreed targets to reaching zero emissions by mid-century. However, there is no agreement on how to deliver these commitments. The absence of a clear plan is a result of two incomplete approaches: politicians and the leaders of high-emitting businesses all proclaim that there is no need to constrain today’s activities, because new technologies will make solution easier if we wait; meanwhile specialists in all disciplines attempt to reframe the problem to fit their existing methodologies, but in doing so, miss the essence of the problem – which is scale. As a result, emissions continue to rise, raising the risk of a devastating global famine this century.
To try to identify how the skills and expertise gathered at ICTP can contribute to a safe planet, this talk will begin by exploring the options for future supply of bulk materials. The most likely future, based on current technology trends, is for a radical reduction in total metal supply, which will mainly be provided by recycling.
Responding to this reduced supply requires that we make much better use of much less metal. Partly this depends on extending the life of metal-intensive goods, especially in construction, vehicles and large industrial equipment. This does not generally require innovation in metal forming technology.
However, following a century of virtually limitless supply of low-cost high-performance metal, we have become careless in its use: half of all sheet metal made annually is cut off as scrap during manufacturing; most components are over-designed by a factor of two or more. This sets the agenda for how metal forming technologists can contribute to making a safe planet. The talk will attempt to identify the areas where different technologies can make most impact and give recent examples of where innovation has begun to have scalable impact.
Julian Allwood is Professor of Engineering and the Environment at the University of Cambridge. He worked for 10 years for Alcoa on flat rolling, before academic positions at Imperial College and Cambridge. His research group develops new manufacturing technologies for metals and strategies to mitigate climate change. From 2009-13 he held an EPSRC Leadership Fellowship, to explore Material Efficiency as a climate mitigation strategy – delivering material services with less new material. This led to publication in 2012 of the book “Sustainable Materials: with both eyes open” which can be read online at www.withbotheyesopen.com and was listed by Bill Gates as “one of the best six books I read in 2015.”
Julian was a Lead Author of the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) with a focus on mitigating industrial emissions. He is an Honorary Fellow of the Institution of Materials, Minerals and Mining, a Fellow of the International Academy of Production Engineering (CIRP) and served as chairman of its metal forming section, a member of the UK’s Energy Research Partnership and for ten years was joint editor-in-chief of the Journal of Materials Processing Technology. He was elected as a Fellow of the Royal Academy of Engineering in 2017 and in 2021 was awarded the triennial Japan Society for Technology of Plasticity International Prize for Research and Development in Precision Forging.
From 2019-24 he is director of UK FIRES – a £5m industry and multi-university programme aiming to explore all aspects of Industrial Strategy compatible with delivering zero emissions by 2050. ‘Absolute Zero’, the first publication of UK FIRES attracted widespread attention including a full debate in the House of Lords in Feb 2020, and has led to a string of other reports, research and impact.
Digital tools are important aids for the optimisation of forging processes. Three approaches are presented here that support the process design, the process monitoring and the modelling. The design of an economical staging sequence is characterised, for example, by fold- and crack-free forming with few forming steps and little excess material. In order to economically design a staging sequence for complex component geometries, a targeted design is necessary. Preforms should be designed in such a way that the mass distribution along the longitudinal axis is well approximated to the finished form. With conventional methods, such as the mass distribution diagram in 3D space, designing geometrically complex components is very time-consuming. In reality, stage sequences are often only designed in a shortened way, depending on the necessity or the possibilities of the respective company, and the design is often based on the experience knowledge of the employees or on already existing reference processes. Here, an AI-based method for determining the mould parting line as well as for the automated design of economic stage sequences is presented. The method does not rely on reference processes of already existing staging sequences since the necessary information is automatically extracted from the forging geometry.
In addition, developments in the data-based process monitoring in die forging and the resulting improved numerical modelling for the wear calculation of forging dies are discussed.
Bernd-Arno Behrens is Head of the Institute of Forming Technology and Machines (IFUM) of the Leibniz Universitaet Hannover. Since July 2015 he has been Spokesperson of the Collaborative Research Centre 1153 “Process Chain for Manufacturing Hybrid High-Performance Components by Tailored Forming”.
Bernd-Arno Behrens studied mechanical engineering at the Universitaet Hannover with emphasis on production technology. He finished his PhD with honors in 1997 at the Institute of Forming Technology and Machines (IFUM) of the Universitaet Hannover under the supervision of Prof. Dr.-Ing. Eckart Doege. From 1997 to 2003 he worked in a leading position with Salzgitter Mannesmann Forschung GmbH until he became Full Professor in September 2003. Since 2004 he has been heading the Institute of Forming Technology and Machines (IFUM) of the Leibniz Universitaet Hannover. Also in 2004 he became Spokesman of the Board of the Material Testing Institute Hannover (MPA) and Board Member of the Hannover Centre for Production Technology (PZH). Since 2005 he is Managing Partner of the Institute of Integrated Production Hannover gGmbH (IPH) and in 2006 he became a member of the Supervisory Board of the PZH.
His main research interests focus on sheet metal forming, bulk metal forming, forming machines, material characterization and simulation as well as biomedical engineering.
Bernd-Arno Behrens is a member of numerous scientific academies and associations and acts as evaluator for the German Research Foundation (DFG) and the German Federation of Industrial Research Associations „Otto von Guericke“ (AiF). Furthermore, since 2006, he has been a member of the Editorial Committee ‘Production Engineering, Research and Development’ of the WGP.
Machine Learning in Advancing Metal Processing Technologies
The combination of the mechanics-driven and data-driven approaches have received increasing attention in both academic and industry. In this talk, I will post the challenges that we are facing to the broad manufacturing community and use two manufacturing processes, i.e., metal powder-based additive manufacturing and sheet metal forming as demonstration cases. Specifically, I will show how the integration of the fundamental process mechanics, process control, and techniques including machine learning to achieve effective and efficient predictions of material’s mechanical behavior due to or during a manufacturing process. Our solutions particularly target three notoriously challenging aspects of the process, i.e., long history-dependent properties, complex geometric features, and the high dimensionality of their design space.
Cardiss Collins Professor Jian Cao (NAE, MIT’95, MIT’92, SJTU’89) specialized in innovative manufacturing processes and systems, particularly in the areas of deformation-based processes and laser additive manufacturing processes. She founded the university research center on Manufacturing Science and Innovation at Northwestern, known as NIMSI. Cao is the Editor-in-Chief of Journal of Materials Processing Technology (JMPT). Prof. Cao is an elected member of the U.S. National Academy of Engineering (NAE), a Fellow of American Association for the Advancement of Science (AAAS), ASME, CIRP and SME. Her major awards include ASME Milton C. Shaw Manufacturing Research Medal, SME Gold Medal, DoD Vannevar Bush Faculty Fellowship, Charles Russ Richards Memorial Award from ASME and Pi Tau Sigma, SME Frederick W. Taylor Research Medal, ASME Blackall Machine Tool and Gage Award, and NSF CAREER Award. She served as President of the SME North America Manufacturing Research Institute, Chair of CIRP STC-F, Chair of ASME Manufacturing Engineering Division, and Program Director at the National Science Foundation. Cao now serves on the National Materials and Manufacturing Board of the National Academies, Board of Directors of SME, Board of mHUB – accelerator for hardtech innovation and manufacturing in Chicago.
The past, present and future challenges in microforming
Microforming is a promising micro-manufacturing process for fabrication of meso-/micro-scaled parts via plastic deformation of bulk or sheet materials. In microforming process, there are many unique behaviors and phenomena, which are different from those in macro-scaled forming processes, and thus result in different challenges in the past, present and future. In this talk, these challenges will be delineated and elucidated. The size effects (SE) induced by different size-scaled factors and their manifestations will be outlined and discussed, and how the SEs generate size-dependent process behaviors, process performances, and the quality and properties of the fabricated microparts, and their scatters will be systematically explicated and thoroughly analyzed. By using microforming of sheet and wire metals as instances, the above-described challenges will be exemplified and characterized.
Mingwang FU (M.W. FU) is the Chair Professor of Advanced Manufacturing in the Dept of Mech. Eng., The Hong Kong Polytechnic University (The HK PolyU). He is the Fellow of Society of Manufacturing Engineers (SME) and Hong Kong Institute of Engineers (HKIE). Prof Fu is the Royal Society Wolfson Visiting Fellow and an Associate Director of Research Institute for Advanced Manufacturing at PolyU. From 1987 to 1995, he worked as a faculty member in China. Upon completion of his PhD study in the National University of Singapore in 1997, he joined the Singapore Institute of Manufacturing Technology as a Senior Research Engineer. In Aug 2006, he joined the HK PolyU as a faculty member. Professor Fu is quite active in exploring advanced materials processing, multi-scaled manufacturing, metal forming, damage and fracture in manufacturing, structure fatigue in product service, and micro-mechanics in manufacturing. These efforts aim at seeking for an epistemological understanding of the physical and scientific nature behind these disciplines, advancing the knowledge in these areas, and successfully addressing a plethora of challenges and bottlenecked issues the explorations face, and eventually developing the state-of-the art manufacturing processes. His researches benefited the development of the technologies in the above-described fields and led to more than 260 journal publications, 6 monographs and one volume of the Encyclopedia of Materials: Metals and Alloys, published by Springer-Verlag London Ltd, CRC Press, Taylor & Francis Group, and Elsevier. Professor Fu is also sitting in the editorial board or as Associate Editor of many prestigious journals, including Int. J. Plast., Int. J. Mach. Tools Manuf., Int. J. Mech. Sci., Mater. Des., Int. J. Damage Mech., Int. J. Adv. Manuf. Technol., etc. He often gives keynote or plenary talk in many international conferences in different countries.
Advanced material testing methods for sheet metals
Improvement of the predictive accuracy for defect formation (such as fracture and springback) is key to realizing trial-and-error-less manufacturing. In metal forming processes, materials are subjected to various multiaxial stresses and stress reversals. Therefore, the parameters of the material models used in finite element simulations should be determined using the material testing methods that accurately reproduce the stress states generated in real forming processes. This lecture reviews the advanced material testing methods for sheet metals. Special attention is given to the anisotropic plastic deformation behavior of industrial materials and to the validation of the material models under both linear and nonlinear stress paths for large plastic strain ranges. In addition, examples of improving the accuracy of forming simulations by selecting appropriate material models are presented.
Professor Kuwabara received a degree of Doctor of Engineering from Tokyo Institute of Technology (TIT), Japan, in 1987. The same year, he became a research associate at the Laboratory of Precision Machinery and Electronics, TIT. In 1989 he moved to Department of Industrial Mechanical Engineering, Faculty of Engineering, Tokyo University of Agriculture and Technology (TUAT), Japan, where he conducted scientific research and education on plasticity and metal forming technologies more than 30 years. Dr. Kuwabara is currently a distinguished professor at Division of Advanced Mechanical Systems Engineering, Institute of Engineering, TUAT. His research focuses on the development of advanced material testing methods for metal sheets and tubes, as well as for polymer tubes, for enhancing the accuracy of material models to be used in forming simulations. Professor Kuwabara is also an Adjunct Professor at the Graduate Institute of Ferrous and Energy Materials Technology, Pohang University of Science and Technology, since 2010. In addition, he served as a member of the Board of Directors of ESAFORM (2014-2021), the Japan Society of Technology of Plasticity, and the Iron and Steel Institute of Japan. Professor Kuwabara has actively participated in the scientific committees of various international conferences. He was the chairman of the 11th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes (NUMISHEET 2018), which was held in Tokyo in 2018.
Space- and time-varying friction in metal forming: risks and opportunities, experimental and numerical assessment
Friction is known as a difficult-to-assess input in metal forming. This is all the more damageable as it may have a huge impact on certain processes and the quality of their product. In spite of a large amount of research done and a vast literature, which friction law to choose and how to identify the corresponding coefficients remains a puzzle in most cases. This is due to multiple interacting mechanisms involving an almost unlimited number of variables.
Furthermore, these variables, e.g. contact conditions (contact pressure, temperature, sliding velocity, lubrication regime…) may vary across extended contacts, making it probable that friction coefficients be non-uniform. Transient friction may not be identical to steady state friction either : in general, friction may be space- and time-dependent.
In many situations, a reasonable compromise solution can be found, in that sensible and useful results can be obtained, with a single friction coefficient, constant in space and time. The purpose of this presentation is to review a few cases where this simplification does not hold, i.e. friction on different tools or at different stages of a process may not be considered identical without significant errors. Based on literature and personal recent work, examples of this will be described, e.g.
different roles of friction on rollers, guide shoes and plug in Mannesmann 2-roll piercing,
consequences of internal vs external friction in tube pilgering,
impact of friction on flow in mixed forward / backward extrusion,
blankholder friction vs tool radii friction in deep drawing and stamping,
…
Some thoughts will be given to the measurement of such time- and space-dependent friction, either from the process itself using a sufficient number of observable data, usually by exploiting process modelling; or using different friction tests mimicking conditions on different tools / at different places, such as in deep drawing.
Tentative examples on how non-uniform friction is or could be used to optimize certain processes will finally be addressed.
Graduated from Ecole Centrale as a Materials Engineer in 1979, PhD on modelling soap lubrication in wire drawing in 1983, PM has spent a whole career on metal forming process modelling and tribology, maintaining a balance between experimental approaches (tribotesting, material and surface characterization) and numerical developments (development of constitutive and tribological models, process simulation). His interests encompass modelling of lubrication, friction and wear, boundary lubrication, tribochemistry and adhesive transfer, superficial material characterization by indentation or scratch testing, forming and assembling of coated or bi-materials, roll deformation, strip profile and flatness in strip rolling, effect of plastic anisotropy in bulk metal forming processes, mechanical modelling and tribology of tube pilgering...
From homogeneous to heterogeneous mechanical testing of metallic materials
The strength of materials is an essential information in mechanical design and specific tests, like the tensile test, have been used since several centuries. Before necking, such a test is homogeneous and corresponds to a single mechanical state, defined by the stress and strain tensors. With virtual mechanical design, there is a need for a large number of mechanical states to calibrate advanced models for hardening, anisotropy and rupture. Two trends are existing, either increasing the number of homogeneous tests or using few heterogeneous tests. In the last case, using full-field measurements and finite element simulations, the richness of the mechanical states of only one test is exploited to identify material parameters. This presentation will focus on a review of heterogeneous tests for metallic sheets and on how to evaluate the quality and diversity of the information. As well as on methods to design heterogeneous tests and strengths and limitations of the approach. Is there a path toward a single, standardized heterogeneous test?
Sandrine Thuillier is full professor in mechanical engineering at Université Bretagne Sud (France). Her research activities are the experimental characterisation of the mechanical behaviour of materials at room and warm temperatures, mainly sheets of aluminium alloys, steels and titanium alloys. She also focuses her efforts on material parameter identification by inverse methodologies, as these parameters are an important input to the numerical models based on elasto-visco-plasticity, anisotropic yield and macroscopic rupture. Finally, she applies her scientific skills to metal forming processes, such as deep drawing, hemming, surface defects, bending, twisting and cutting. She chaired the IDDRG (International Deep Drawing Research Group) conference in June 2022 in Lorient. She is a member of the board of directors of the ESAFORM association and deputy-secretary of this association. Moreover, she is an associate-editor for the journal “Mechanics & Industry”. She has co-authored more than 170 papers published in peer-reviewed international journal or presented at international conferences.
