Additive technology and design process: an innovative tool to drive and assist product development Francesco TAMBURRINO, Valeria PERROTTA, Raffaella AVERSA, Antonio APICELLA
Department of Architecture and Industrial Design, Second University of Naples, Aversa, Italy E-mail:
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Abstract
The object of study regards the analysis of existing relationship between additive technologies and design process. Additive technologies are defined by a range of technologies that are capable of translating virtual solid model data(CAD) into physical models in a quick and easy process. The data are broken down into a series of layer of a finite thickness. These layers are added together to create the physical product. The great widespread of additive technologies, FabLab and 3D printing is leading to talk of third industrial revolution, so the aim of the work is to understand what is the true role of these technologies inside the product development process. Very often the additive technologies are used when the design process is already closed, just to show and present the final product to market and before to start with the definitive manufacturing process. This kind of approach leads to have a partial utilization of the additive technologies potentialities, considering the possibility to work with materials of a different nature and structural behavior, the great freedom of shape and aesthetic, the opportunity to verify ergonomic and functional aspects. Therefore the additive technologies can be used, during the design process, as a tool to drive and assist the product development. Keywords: additive manufacturing, design process, materials and technologies
1. Introduction
The use of additive manufacturing has increased significantly in previous years. This manufacturing process is used by multiple industry subsectors, including motor vehicles, aerospace, machinery, electronics, and medical products. Currently, however, additive manufactured products represent less than 1% of all manufactured products in the U.S. As the costs of additive manufacturing systems decrease, this technology may change the way that consumers interact with producers. Additive manufacturing technology opens up new opportunities for the economy and society. It can facilitate the customized production of strong lightweight products and it allows designs that were not possible with previous manufacturing techniques. Additive Manufacturing (AM) defines a family of technologies for making objects of almost any shape from virtual 3D model data through additive processes in which successive layers of material are laid down. The main difference between AM and other conventional processing technologies is the “layer by layer additive” construction manner, which makes the AM can manufacture designed parts with extremely complex geometries without the use of fixtures, tooling, mold or any other additional auxiliary. For the AM field, we have six main manufacturing processes: Fused Deposition Modelling (FDM), 3D Fiber Deposition (3DF), 3D Printing, Stereolithography (STL), Selective Laser Sintering (SLS) and Electron Beam Melting (EBM). The FDM process, is based on polymers melts passing through a nozzle and a molten fibre is further deposited on the surface of a moving platform or merges with the previous layer where it cools down and solidifies.
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Geometrical and morphological parameters of scaffold are influence by the processing conditions, namely, nozzle diameter, writing speed, extrusion rate and polymer physics (de Mulder et al 2009). In case of 3DF, it does not require temperature enabling the use of cell-laden materials to be processed. 3D printing creates tri-dimensional objects by depositing liquid binder onto a powdered bed. This liquid may act as glue or promote a reaction causing the particles to bind together. After each layer, a new powder bed in spread and the object is created by “n” cycles of this procedure. In this case, the unbounded particles aid the construction of the following layers as it provides temporary support to the object (Butscher, 2011). SLS uses IR lasers to heat up the powder beyond it is melting point causing neighbouring particles to fuse forming a solid structure. When each layer if finished, a new powder layer is placed with a mechanical roller and the exceeding material from the precious layer provides in place to support the continuance of the process (Bártolo, 2009). Finally the EBM that is a technology similar to the SLS, but it uses an electron beam as its power source, as opposed to a laser.
Tab. 1: It is summarized a list of materials for each type of scaffold technology
Compared with the design for traditional processing technologies, the design for AM has greatly increased the space of freedom for the designers. Altough, there still are a set of limitations or constraints existing in the AM processing technologies, the correct use of AM plus the knowledge of materials is the key to produce a flexible amount of products, as market requires. When designing, they should be taken into consideration. Due to the actual economic situation, the AM is the right choise that meets customers satisfaction and industrial strategies to reduce time to market and to save costs. The aim is to analyze the true role of additive technologies with a particular reference to materials, technologies, manufacture and design process.
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2. Process planning structure and materials
Though AM has been widely regarded as “one button” processing technology due to its high automation, the preparation work before manufacturing should be also done by technical expert using some tools and related experience or knowledge. The preparation work contains tasks from the selection of suitable manufacturing scenarios, which include AM machine, material, machine set-up parameters etc., to 3D data checking and detailed process planning, such as orientation, support design, slicing and tool path generation. Here in based on the comparison with traditional process planning, this paper gives a two-level process planning framework for the systematic process planning in AM, which is depicted in Table. 2.
Tab. 2: Process Planning framework for AM.
Macro process planning is the first level or stage of process planning in AM. The main contents contain the manufacturability analysis, selection of manufacturing scenarios and setting up the original processing parameters. These tasks can be finished only under full understanding of AM processes characteristics and limitations as well as the design and production requirements. Hence, this process planning stage could be directly connected or associated with the conception design stage where manufacturability analysis based on analyzing the design requirements and selection of manufacturing scenarios based on functional and production requirements are both should be carried out. Micro process planning stage mainly focuses on the detailed technical aspects. The main contents include: 3D CAD data checking, repairing, scaling et al.; determination of part’s build orientation; determination of the strategy for placing or packing parts in the build platform or chamber when under multi-parts production context; support generation for some AM processes that need support structures; determination of a slicing strategy; determination of a tool-path or scanning strategy; determination of post processing strategies. Apparently, the main tasks in this micro planning stage have a very tight relationship with the detail design for AM since the results of these tasks directly determine a design’s physical realization and mechanical properties.
3. Potentialities and limitations
The AM has great potentialities to result a good tool not only to prototype or to make a small production, but especially to drive and assist the product development during the design process. In this paragraph we will do a list of advantages and limitations linked to the use of the additive technologies for a designer. First of all with the AM a designer can work on the form finding and design optimization, having a great freedom of shape. This approach allows to create more complex geometry than traditional manufacturing techniques(injection moulding for example). This means to have the possibility to work on the material reduction, to enhance the mechanical behavior of the designed object developing its shape, to study functionality and usability of the design, including the ergonomic aspects too. These features give the possibility to use the AM to obtain an optimized design that takes into account multiple aspects.
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Fig. 1: EBM sintered titanium, supplied by Adler-Ortho, spa.
AM allows also to have a responsive production, in fact they offer faster lead times than the traditional manufacturing processes. This means to have the possibility to test the appeal of a product on the market(online, for example) and then to decide to start or stop its production or to modify the design. Another benefit of the AM over the traditional machine tooling is the lower cost of manufacturing. If we compare, for example, the additive technologies to the main manufacturing process of the polymers, with AM we don’t need production plants, molds or large facilities. If we compare, instead, additive technologies to the CNC milling process, in the first case we don’t have material waste and so we have a cheaper and environmentally sustainable production. The AM is also a good tool to have prototypes, low volume production and customized products that follow the needs of even more demanding users. Another strong aspect related to the AM for the present and especially for the future is the opportunity to have shorter supply chains, having the possibility to create a network of local, regional, national manufacturing centers, in this way is not the product to travel, but its digital file. This means less cost, less pollution and shorter waiting times too. The AM is an extremely flexible and adaptable tool. For this reason it has a large range of application: rapid prototyping, rapid tooling, automotive, aerospace, medical implants, nanomanufacturing, architecture, etc. On the other hand currently the AM has limitations too. With AM, for example, low volume production is faster than conventional manufacturing, but higher volumes are considerably slower, so this tool cannot fully replace the conventional manufacturing processes. Another aspect to improve is related to the possibility to use a larger range of materials, although the metal sintering is helping to open up these technologies to industrial users. Finally other issues linked to the AM use are their difficulty to compete with traditional techniques on reliability and reproducibility and the grave concern regarding the protection of the intellectual property. In fact just with a 3D scanner it is possible to copy an object for reprinting it in 3D.
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Fig. 2: Additive manufacturing timeline, courtesy of Graham Tromans
4. Concluding remarks
The purpose of the paper presented is to achieve a deeper analysis of the additive technologies and their use for the industrial design, underlining the true potentialities and weaknesses of these technologies inside the design process, with a look at the present and another at the future. In particular the objective is to show that a smarter use of the additive technologies as a tool to drive and assist the product development is possible. Especially the great freedom of shape ensured by the AM should be exploited to design optimized and sustainable products, where less materials and weight meet better performance. The utilization of these technologies should be explored not only for aesthetic purposes and for rapid prototyping, but especially to achieve advanced functional, structural, environmental and ergonomic performances.
Bibliographical References [1] ROYAL ACADEMY OF ENGINEERING. Additive manufacturing: opportunities and constraints. London: Publisher, 2013. ISBN 978-1-909327-05-4 [2] Manuscript Number: PROCIR-D-13-00847R3. ZHANG, Yicha. Evaluating the Design for Additive Manufacturing: A Process Planning Perspective. In AA.VV. A. Bernard, R. Kumar Gupta, R. Harik. 24th CIRP Design Conference. Milano: Publisher, 2014, p. 1-8. [3] DETC2014-34067. VERMA, Anoop. Computational Geometric Solutions For Efficient Additive Manufacturing Process Planning. In AA.VV. RAI Rahul. Proceedings of the ASME 2014 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2014. Buffalo, USA: Publisher, 2014 [4]. TOJEIRA, A. Structure Development during Additive Manufacturing. In AA.VV. S. Biscaia, T. Viana, P.J. Bártolo & G. R. Mitchell. Portugal: Publisher, 2013. [4] Publisher proceedings of a conference are cited as a monograph.
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[5] KULKARNI, P. MARSAN, A. DUTTA, D. A review of process planning techniques in layered manufacturing. In AA.VV. Rapid Prototyping J. Publisher, 2000, p. 16-35. [6] http://karma.aimme.es/. [7] http://gow.epsrc.ac.uk/NGBOViewGrant.aspx?GrantRef=GR/R13517/01.
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