B.G. Bryden, D.I. Wimpenny and I.R. Pashby
Lastform, a three year EPSRC (IMI) programme, has investigated metallic laminating techniques to produce large‐scale production capable tooling. This work is intended as an…
Abstract
Lastform, a three year EPSRC (IMI) programme, has investigated metallic laminating techniques to produce large‐scale production capable tooling. This work is intended as an overview of the research and development performed at the University of Warwick’s Warwick manufacturing Group. The programme was a collaboration between seven industrial partners and three universities with each university having a discreet area of research. The focus at Warwick was to establish robust methods of joining metal sheets to form tools for different production processes. Bonding mediums, test parts for process evaluation, sample tools and production tools are described. The advantages of metal laminating for different processes are evaluated. Results include reduced lead‐time and cost savings and enhanced processing capability by the use of conformable heating or cooling channels.
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Aldi Mehmeti, Pavel Penchev, Donal Lynch, Denis Vincent, Nathalie Maillol, Johannes Maurath, Julien Bajolet, David Ian Wimpenny, Khamis Essa and Stefan Dimov
The paper reports an investigation into the mechanical behaviour of hybrid components produced by combining the capabilities of metal injection moulding (MIM) with the laser-based…
Abstract
Purpose
The paper reports an investigation into the mechanical behaviour of hybrid components produced by combining the capabilities of metal injection moulding (MIM) with the laser-based powder bed fusion (PBF) process to produce small series of hybrid components. The research investigates systematically the mechanical properties and the performance of the MIM/PBF interfaces in such hybrid components.
Design/methodology/approach
The MIM process is employed to fabricate relatively lower cost preforms in higher quantities, whereas the PBF technology is deployed to build on them sections that can be personalised, customised or functionalised to meet specific technical requirements.
Findings
The results are discussed, and conclusions are made about the mechanical performance of such hybrid components produced in batches and also about the production efficiency of the investigated hybrid manufacturing (HM) route. The obtained results show that the proposed HM route can produce hybrid MIM/PBF components with consistent mechanical properties and interface performance which comply with the American Society for Testing and Materials (ASTM) standards.
Originality/value
The manufacturing of hybrid components, especially by combining the capabilities of additive manufacturing processes with cost-effective complementary technologies, is designed to be exploited by industry because they can offer flexibility and cost advantages in producing small series of customisable products. The findings of this research will contribute to further develop the state of the art in regards to the manufacturing and optimisation of hybrid components.
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Jason B. Jones, David I. Wimpenny and Greg J Gibbons
This paper aims to investigate the effects on material properties of layer-by-layer application of pressure during fabrication of polymeric parts by additive manufacturing (AM)…
Abstract
Purpose
This paper aims to investigate the effects on material properties of layer-by-layer application of pressure during fabrication of polymeric parts by additive manufacturing (AM). Although AM, also known popularly as 3D printing, has set a new standard for ease of use and minimal restraint on geometric complexity, the mechanical part properties do not generally compare with conventional manufacturing processes. Contrary to other types of polymer processing, AM systems do not normally use (in-process) pressure during part consolidation.
Design/methodology/approach
Tensile specimens were produced in Somos 201 using conventional laser sintering (LS) and selective laser printing (SLP) – a process under development in the UK, which incorporates the use of pressure to assist layer consolidation.
Findings
Mechanical testing demonstrated the potential to additively manufacture parts with significantly improved microstructure and mechanical properties which match or exceed conventional processing. For example, the average elongation at break and ultimate tensile strength of a conventionally laser-sintered thermoplastic elastomer (Somos 201) increased from 136 ± 28 per cent and 4.9 ± 0.4 MPa, to 513 ± 35 per cent and 10.4 ± 0.4 MPa, respectively, when each layer was fused with in-process application of pressure (126 ± 9 kPa) by SLP.
Research limitations/implications
These results are based on relatively small sample size, but despite this, the trends observed are of significant importance to the elimination of voids and porosity in polymeric parts.
Practical implications
Layerwise application of pressure should be investigated further for defect elimination in AM.
Originality/value
This is the first study on the effects of layerwise application of pressure in combination with area-wide fusing.
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David Ian Wimpenny and Gregory John Gibbons
This work was performed within IMI Spray Mould, an EPSRC joint funded programme, aimed at developing a manufacturing route for large aerospace composite forming tooling, based on…
Abstract
This work was performed within IMI Spray Mould, an EPSRC joint funded programme, aimed at developing a manufacturing route for large aerospace composite forming tooling, based on metal spray technologies. Assesses the mechanical properties of Invar steel coatings, deposited using electric arc spraying, and correlates these properties to the spray parameters and processes used so as to offer coatings with characteristics appropriate to the tooling requirements. In particular, two processing methods, inert and air atomisation, and three arc spray gun configurations (air cap design) are evaluated. The mechanical properties of the coatings are found to be low compared to bulk Invar, regardless of the spray parameters and hardware used. Inert arc spraying affords more consistent coating characteristics but this comes with a compromised durability. The spray hardware is found to be more significant in determining the coating properties than the parameters employed.
Matthew James Benning and Kenny Dalgarno
This paper aims to develop and then evaluate a novel consolidation and powder transfer mechanism for electrophotographic 3D printing, designed to overcome two longstanding…
Abstract
Purpose
This paper aims to develop and then evaluate a novel consolidation and powder transfer mechanism for electrophotographic 3D printing, designed to overcome two longstanding limitations of electrophotographic 3D printing: fringing and a build height limitation.
Design/methodology/approach
Analysis of the electric field generated within electrophotographic printing was used to identify the underlying causes of the fringing and build height limitations. A prototype machine was then designed and manufactured to overcome these limitations, and a number of print runs were carried out as proof of concept studies.
Findings
The analysis suggested that a machine design which separated the electrostatic powder deposition of the print engine from the layer transfer and consolidation steps is required to overcome fringing and build height limitations. A machine with this build architecture was developed and proof of concept studies showed that the build height and fringing effects were no longer evident.
Research limitations/implications
Electrophotography (EP) was initially seen as a promising technology for 3D printing, largely because the potential for multi-material printing at high speed. As these limitations can now be overcome, there is still potential for EP to deliver a high-speed 3D printing system which can build parts consisting of multiple materials.
Originality/value
The analysis of EP, the new method for the transfer and consolidation of layers and the proof of concept study are all original and provide new information on how EP can be adopted for 3D printing.
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Radhwan Bin Hussin, Safian Bin Sharif, Shayfull Zamree Bin Abd Rahim, Mohd Azlan Bin Suhaimi, Mohd Tanwyn Bin Mohd Khushairi, Abdellah Abdellah EL-Hadj and Norshah Afizi Bin Shuaib
Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype…
Abstract
Purpose
Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts.
Design/methodology/approach
The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted.
Findings
Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles).
Research limitations/implications
The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available.
Originality/value
This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.
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Satabdee Dash, Axel Nordin and Glenn Johansson
Dual design for additive manufacturing (DfAM) takes into account both the opportunities and constraints of AM simultaneously, which research shows is more effective than…
Abstract
Purpose
Dual design for additive manufacturing (DfAM) takes into account both the opportunities and constraints of AM simultaneously, which research shows is more effective than considering them separately. Unlike existing reviews, this paper aims to map DfAM research within the engineering design process, focusing solely on studies adopting dual DfAM. Additionally, it aims to suggest future research directions by analysing prominent research themes and their inter-relationships. Special emphasis is on theme inter-relationships concerning the conceptual, embodiment and detail design phases.
Design/methodology/approach
The study is based on a systematic literature review of 148 publications from January 2000 to February 2024. After screening, prominent research themes were identified and systematically analysed. Theme inter-relationships were explored using quantitative analysis and chord diagrams.
Findings
The findings reveal that studies either span the entire design process, the early design phases or the later design phases. Most research focuses on the later design phases, particularly within themes of design optimisation, design evaluation and AM-specific manufacturing constraints. The most frequent theme inter-relationship occurs between design optimisation and AM-specific manufacturing constraints. Overall, the findings suggest future research directions to advance dual DfAM research, such as development of design rules and guidelines for cellular structures.
Originality/value
This review proposes a model by mapping prominent themes of dual DfAM research in relation to the engineering design process. Another original contribution lies in analysing theme inter-relationships and visualising them using chord diagrams – a novel approach that did not exist before.
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P.M. Dickens, R. Stangroom, M. Greul, B. Holmer, K.K.B. Hon, R. Hovtun, R. Neumann, S. Noeken and D. Wimpenny
The Tooling and Casting subgroup of the European Action on Rapid Prototyping (EARP) has undertaken a project to investigate the problems associated with using rapid prototype…
Abstract
The Tooling and Casting subgroup of the European Action on Rapid Prototyping (EARP) has undertaken a project to investigate the problems associated with using rapid prototype models as sacrificial patterns for investment casting. The accuracy and surface finish of the models and the castings were also assessed so that a comparison could be made. Models from each process were manufactured by different members of EARP and then three foundries were each given a set of models to convert to castings. Observes that one of the oldest metal manufacturing techniques, which dates back to 4000‐6000 BC, is being used with one of the most modern ‐ rapid prototyping.
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Irina Tatiana Garces and Cagri Ayranci
A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the…
Abstract
Purpose
A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the limitations and possible improvements in the different research areas within the different AM techniques. The purpose of this study is to identify academic and industrial opportunities.
Design/methodology/approach
This paper introduces the reader to three-dimensional (3 D) and four-dimensional printing of shape memory polymers (SMPs). Specifically, this review centres on manufacturing technologies based on material extrusion, photopolymerization, powder-based and lamination manufacturing processes. AM of SMPC was classified according to the nature of the filler material: particle dispersed, i.e. carbon, metallic and ceramic and long fibre reinforced materials, i.e. carbon fibres. This paper makes a distinction for multi-material printing with SMPs, as multi-functionality and exciting applications can be proposed through this method. Manufacturing strategies and technologies for SMPC are addressed in this review and opportunities in the research are highlighted.
Findings
This paper denotes the existing limitations in the current AM technologies and proposes several directions that will contribute to better use and improvements in the production of additive manufactured SMPC. With advances in AM technologies, gradient changes in material properties can open diverse applications of SMPC. Because of multi-material printing, co-manufacturing sensors to 3D printed smart structures can bring this technology a step closer to obtain full control of the shape memory effect and its characteristics. This paper discusses the novel developments in device and functional part design using SMPC, which should be aided with simple first stage design models followed by complex simulations for iterative and optimized design. A change in paradigm for designing complex structures is still to be made from engineers to exploit the full potential of additive manufactured SMPC structures.
Originality/value
Advances in AM have opened the gateway to the potential design and fabrication of functional parts with SMPs and their composites. There have been many publications and reviews conducted in this area; yet, many mainly focus on SMPs and reserve a small section to SMPC. This paper presents a comprehensive review directed solely on the AM of SMPC while highlighting the research opportunities.
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Gregory John Gibbons, Robert G. Hansell, A.J. Norwood and P.M. Dickens
This paper details the development of a rapid tooling manufacturing route for the gravity and high‐pressure die‐casting industries, resulting from an EPSRC funded collaborative…
Abstract
This paper details the development of a rapid tooling manufacturing route for the gravity and high‐pressure die‐casting industries, resulting from an EPSRC funded collaborative research project between the Universities of Warwick, Loughborough and DeMontfort, with industrial support from, amongst others, MG Rover, TRW Automotive, Sulzer Metco UK Ltd and Kemlows Diecasting Products Ltd. The developed process offers the rapid generation of mould tools from laser‐cut laminated sheets of H13 steel, bolted or brazed together and finish machined. The paper discusses the down‐selection of materials, bonding methods and machining methods, the effect of conformal cooling channels on process efficiency, and the evaluation of a number of test tools developed for the industrial partners. The paper also demonstrates the cost and time advantages (up to 50 and 54 per cent, respectively) of the tooling route compared to traditional fabrication methods.