Research Towards High Speed Freeforming

Additive manufacturing (AM) methods are currently utilised for the manufacture of prototypes and low volume, high cost parts. This is because in most cases the high material costs and low volumetric deposition rates of AM parts result in higher per part cost than traditional manufacturing methods. This paper brings together recent research aimed at improving the economics of AM, in particular Extrusion Freeforming (EF). A new class of machine is described called High Speed Additive Manufacturing (HSAM) in which software, hardware and materials advances are aggregated. HSAM could be cost competitive with injection moulding for medium sized medium quantity parts. A general outline for a HSAM machine and supply chain is provided along with future required research

The potential of additive manufacturing in the smart factory industrial 4.0: A review

Additive manufacturing (AM) or three-dimensional (3D) printing has introduced a novel production method in design, manufacturing, and distribution to end-users. This technology has provided great freedom in design for creating complex components, highly customizable products, and efficient waste minimization. The last industrial revolution, namely industry 4.0, employs the integration of smart manufacturing systems and developed information technologies. Accordingly, AM plays a principal role in industry 4.0 thanks to numerous benefits, such as time and material saving, rapid prototyping, high efficiency, and decentralized production methods. This review paper is to organize a comprehensive study on AM technology and present the latest achievements and industrial applications. Besides that, this paper investigates the sustainability dimensions of the AM process and the added values in economic, social, and environment sections. Finally, the paper concludes by pointing out the future trend of AM in technology, applications, and materials aspects that have the potential to come up with new ideas for the future of AM explorations

Latest Developments in Industrial Hybrid Machine Tools that Combine Additive and Subtractive Operations

Hybrid machine tools combining additive and subtractive processes have arisen as a solution to increasing manufacture requirements, boosting the potentials of both technologies, while compensating and minimizing their limitations. Nevertheless, the idea of hybrid machines is relatively new and there is a notable lack of knowledge about the implications arisen from their in-practice use. Therefore, the main goal of the present paper is to fill the existing gap, giving an insight into the current advancements and pending tasks of hybrid machines both from an academic and industrial perspective. To that end, the technical-economical potentials and challenges emerging from their use are identified and critically discussed. In addition, the current situation and future perspectives of hybrid machines from the point of view of process planning, monitoring, and inspection are analyzed. On the one hand, it is found that hybrid machines enable a more efficient use of the resources available, as well as the production of previously unattainable complex parts. On the other hand, it is concluded that there are still some technological challenges derived from the interaction of additive and subtractive processes to be overcome (e.g., process planning, decision planning, use of cutting fluids, and need for a post-processing) before a full implantation of hybrid machines is fulfilledSpecial thanks are addressed to the Industry and Competitiveness Spanish Ministry for the support on the DPI2016-79889-R INTEGRADDI project and to the PARADDISE project H2020-IND-CE-2016-17/H2020-FOF-2016 of the European Union's Horizon 2020 research and innovation program

Experimental and analytical studies of a CO2 laser-based flexible fabrication method for dies and molds

Laser-based flexible fabrication (LBFF), a solid freeform fabrication (SFF) method based on laser-cladding process, was developed as an alternative to conventional machining methods for producing dies and molds. LBFF is similar to processes such as LENS with additional features including shaped beam profile, quasi-coaxial powder delivery, and functionally graded materials. It uses a high-power continuous wave (CW) CO2 laser to fabricate functional tooling, dies and molds, of low surface roughness and high dimensional uniformity. It offers flexibility in designing parts with tailored materials, and in producing parts of complicated geometry.;Functionally graded molds of TiC/Ni-alloy and TiC/Ni-alloy/H13, and functional dies of H13 steel were built up by use of LBFF. Test studies on mold relief ability, strength, and dimensional stability at elevated temperatures were conducted and compared with bench mark H13 mold in gravity casting, in injection molding, and in thermal fatigue environment, respectively. Dies were also tested in aluminum extrusion under laboratory conditions. Results showed that dies and molds fabricated by LBFF had nearly full density, smooth surface (Ra \u3c 25 mum), and improved performance; the functionally graded molds had gradual change in elemental compositions in the transitional regions between distinct layers. In addition to experiments, analytical and finite element modeling of temperature distributions was performed to justify the use of shaped beam profiles in LBFF

Design for Wire + Arc Additive Manufacture: design rules and build orientation selection

Wire + Arc Additive Manufacture (WAAM) is an additive manufacturing technology that can produce near net-shape parts layer by layer in an automated manner using welding technology controlled by a robot or CNC machine. WAAM has been shown to produce parts with good structural integrity in a range of materials including titanium, steel and aluminium and has the potential to produce high value structural parts at lower cost with much less waste material and shorter lead times that conventional manufacturing processes. This paper provides an initial set of design rules for WAAM and presents a methodology for build orientation selection for WAAM parts. The paper begins with a comparison between the design requirements and capabilities of WAAM and other additive manufacturing technologies, design guidelines for WAAM are then presented based on experimental work. A methodology to select the most appropriate build orientation for WAAM parts is then presented using a multi attribute decision matrix approach to compare different design alternatives. Two aerospace case study parts are provided to illustrate the methodology

Studies of laser-based, solid freeform fabrication and coating processes using nanoscale and functionally-graded materials

The purpose of this body of investigation is to examine the role of nanoscale and functionally-graded materials on the laser processing and performance of freeform parts and coatings. Both laser experiments and thermal transport models were utilized to achieve the end goal with applications targeted to dies, molds and light-weight aluminum structures. Specifically a computer-numerical-controlled, high-power CO2 laser system with the aid of computer-aided-design models was used to study: (1) nanoscale material additive manufacturing (NAM) process where Ni-nanoparticles are dispersed in H13 steel molten pool in layer-by-layer fashion to produce three-dimensional gear molds; (2) laser-cladding based freeform fabrication (LBFF) process where shaped beam and novel quasi co-axial powder delivery system were used to produce functionally graded H13/Ni-Cr/TiC mold inserts; and (3) laser sintering (LS) of nanocrystalline diamond powders on aluminum alloy substrate to form thick diamond-like carbon coatings for enhanced wear resistance.;In the NAM process, AISI H13 steel micro-powder (70-100 mum), the standard material in the industry for dies and molds, was blended with Ni nano-powder (70-150 nm) in a volumetric ratio of 4:1 and then laser melted under conditions such that only H13 powder was melted and solidified. With the aid of CAD/CAM models and layer-by-layer addition process, gear-shaped molds were fabricated, characterized and tested. Scanning electron microscopy, surface profilometry, Rockwell and Vicker\u27s hardness tests, corrosion test and injection-molding test using polystyrene were used to evaluate the performance of Ni/H13 molds. Results showed that nanoparticle dispersion has distinct improvements on the functional capability of H13 steel molds to produce precision plastic parts; this is attributed to the role of nanoparticles in enhancing mechanical, chemical and tribological properties.;In the LBFF process, a hollow square-shaped, functionally-graded mold (FGM) insert was designed and built with additive layers of H13 steel, Ni/Cr alloy and TiC using circular and rectangular beam profiles. Finite element numerical methods were applied to determine temperature fields and thermal gradients. The cooling rates were estimated and correlated with secondary dendrite arm spacing. Analysis and characterization of FGM insert revealed nearly full density mold with excellent integrity, favorable microstructures, strong interfaces and high hardness. Strength and dimensional stability of molds were tested in a thermal fatigue environment and compared with baseline H13 steel. Improved strain tolerance, better crack resistance and higher oxidation resistance were the primary benefits of FGM mold.;In LS, nanocrystalline diamond powders (4-8 nm) were sprayed on 6061 aluminum alloy substrates to a nominal thickness of 25 mum by an electrostatic spray method and then laser sintered to consolidate and transform the diamond powder to diamond-like carbon (DLC) for a nominal thickness of 10 mum. Raman spectroscopy and X-ray diffraction analysis confirmed the presence of DLC coatings. Microhardness tests showed an average hardness of 2250 kg/mm 2 (some regions had a hardness of 9000 kg/mm2) indicative of DLC. Fracture toughness and surface roughness were well within the typical ranges of DLC. Scanning electron microscope analysis revealed a near dense, fairly uniform coating with a flaw-free interface. Scratch tests indicated the ability of DLC coating to carry high loads without delamination. One-dimensional thermal energy transport models were formulated based on laser energy absorption, thermal properties of diamond and aluminum, heat conduction and convection and solved using finite element ANSYS code. Results guide to a hypothesis that laser sintering of nano-diamond powder takes place in solid state around 800 K followed by densification and phase transition to DLC and coating/substrate interface heating to nearly the melting temperature of aluminum.;The general findings of this study lead to the conclusion that laser processing of nanoparticles and functionally-graded materials is a prudent approach for not only manufacturing of high performance dies, molds and aluminum structures but also a means of offering the design flexibility in part geometry, tolerance and surface finish

Fabrication and characterization of advanced materials using laser metal deposition from elemental powder mixture

Over the past decades of years, a great deal of money has been spent to machine large and complex parts from high-performance metals (i.e., titanium components for aerospace applications), so users attempt to circumvent the high cost of materials. Laser metal deposition (LMD) is an additive manufacturing technique capable of fabricating complicated structures with superior properties. This dissertation aims to improve the applications of LMD technique for manufacturing metallic components by using various elemental powder mixture according to the following three categories of research topics. The first research topic is to investigate and develop a cost-effective possibility by using elemental powder mixture for metallic components fabrication. Based on the studies of fabricating thin-wall Ti-6Al-4V using elemental powder mixture, comparative close particle number for Ti, Al and V powder could easily get industry qualified Ti-6Al-4V components. The particle number for each element in powder blends has been proved to be a key factor for composition control in the final deposit part. The second research topic focuses on the application improvements of elemental powder manufacturing. By fabricating AlxCoFeNiCu1-x (x = 0.25, 0.5, 0.75) high entropy alloys from elemental powder based feedstocks, it enhances the usage of elemental powder to fabricate novel materials with complex compositions. The third research topic extends the applications of using elemental powder mixture to the broader area. A functionally gradient material (FGM) path is developed to successfully join titanium alloy with γ-TiAl. This dissertation leads to new knowledge for the effective fabrication of unique and complex metallic components. Moreover, the research results of the dissertation could benefit a wide range of industries --Abstract, page iv

AM Envelope:

This dissertation shows the potential of Additive Manufacturing (AM) for the development of building envelopes: AM will change the way of designing facades, how we engineer and produce them. To achieve today’s demands from those future envelopes, we have to find new solutions. New technologies offer one possible way to do so. They open new approaches in designing, producing and processing building construction and facades. Finding the one capable of having big impact is difficult – Additive Manufacturing is one possible answer. The term ‘AM Envelope’ (Additive Manufacturing Envelope) describes the transfer of this technology to the building envelope. Additive Fabrication is a building block that aids in developing the building envelope from a mere space enclosure to a dynamic building envelope. First beginnings of AM facade construction show up when dealing with relevant aspects like material consumption, mounting or part’s performance. From those starting points several parts of an existing post-and-beam façade system were optimized, aiming toward the implementation of AM into the production chain. Enhancements on all different levels of production were achieved: storing, producing, mounting and performance. AM offers the opportunity to manufacture facades ‘just in time’. It is no longer necessary to store or produce large numbers of parts in advance. Initial investment for tooling can be avoided, as design improvements can be realized within the dataset of the AM part. AM is based on ‘tool-less’ production, all parts can be further developed with every new generation. Producing tool-less also allows for new shapes and functional parts in small batch sizes – down to batch size one. The parts performance can be re-interpreted based on the demands within the system, not based on the limitations of conventional manufacturing. AM offers new ways of materializing the physical part around its function. It leads toward customized and enhanced performance. Advancements can for example be achieved in the semi-finished goods: more effective glueing of window frames can be supported by Snap-On fittings. Solving the most critical part of a free-form structure and allowing for a smart combination with the approved standards has a great potential, as well. Next to those product oriented approaches toward future envelopes, this thesis provides the basic knowledge about AM technologies and AM materials. The basic principle of AM opens a fascinating new world of engineering, no matter what applications can be found: to ‘design for function’ rather to ‘design for production’ turns our way of engineering of the last century upside down. A collection of AM applications therefore offers the outlook to our (built) future in combination with the acquired knowledge. AM will never replace established production processes but rather complement them where this seems practical. AM is not the proverbial Swiss-army knife that can resolve all of today’s façade issues! But it is a tool that might be able to close another link in the ‘file-to-factory chain’. AM allows us a better, more precise and safer realization of today’s predominantly free designs that are based on the algorithms of the available software. With such extraordinary building projects, the digital production of neuralgic system components will become reality in the near future – today, an AM Envelope is close at hand. Still, ‘printing’ entire buildings lies in the far future; for a long time human skill and craftsmanship will be needed on the construction site combined with high-tech tools to translate the designers’ visions into reality. AM Envelope is one possible result of this

AM Envelope

This dissertation shows the potential of Additive Manufacturing (AM) for the development of building envelopes: AM will change the way of designing facades, how we engineer and produce them. To achieve today’s demands from those future envelopes, we have to find new solutions. New technologies offer one possible way to do so. They open new approaches in designing, producing and processing building construction and facades. Finding the one capable of having big impact is difficult – Additive Manufacturing is one possible answer. The term ‘AM Envelope’ (Additive Manufacturing Envelope) describes the transfer of this technology to the building envelope. Additive Fabrication is a building block that aids in developing the building envelope from a mere space enclosure to a dynamic building envelope. First beginnings of AM facade construction show up when dealing with relevant aspects like material consumption, mounting or part’s performance. From those starting points several parts of an existing post-and-beam façade system were optimized, aiming toward the implementation of AM into the production chain. Enhancements on all different levels of production were achieved: storing, producing, mounting and performance. AM offers the opportunity to manufacture facades ‘just in time’. It is no longer necessary to store or produce large numbers of parts in advance. Initial investment for tooling can be avoided, as design improvements can be realized within the dataset of the AM part. AM is based on ‘tool-less’ production, all parts can be further developed with every new generation. Producing tool-less also allows for new shapes and functional parts in small batch sizes – down to batch size one. The parts performance can be re-interpreted based on the demands within the system, not based on the limitations of conventional manufacturing. AM offers new ways of materializing the physical part around its function. It leads toward customized and enhanced performance. Advancements can for example be achieved in the semi-finished goods: more effective glueing of window frames can be supported by Snap-On fittings. Solving the most critical part of a free-form structure and allowing for a smart combination with the approved standards has a great potential, as well. Next to those product oriented approaches toward future envelopes, this thesis provides the basic knowledge about AM technologies and AM materials. The basic principle of AM opens a fascinating new world of engineering, no matter what applications can be found: to ‘design for function’ rather to ‘design for production’ turns our way of engineering of the last century upside down. A collection of AM applications therefore offers the outlook to our (built) future in combination with the acquired knowledge. AM will never replace established production processes but rather complement them where this seems practical. AM is not the proverbial Swiss-army knife that can resolve all of today’s façade issues! But it is a tool that might be able to close another link in the ‘file-to-factory chain’. AM allows us a better, more precise and safer realization of today’s predominantly free designs that are based on the algorithms of the available software. With such extraordinary building projects, the digital production of neuralgic system components will become reality in the near future – today, an AM Envelope is close at hand. Still, ‘printing’ entire buildings lies in the far future; for a long time human skill and craftsmanship will be needed on the construction site combined with high-tech tools to translate the designers’ visions into reality. AM Envelope is one possible result of this