No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Additive Manufacturing of Drainage Segments for Cooling System of Crucible Melting Furnaces
Abstract
The cooling process in induction based crucible melting furnaces for Industrial applications is one of the important and challenging factors in production and safety engineering. Accordingly, proper implementation of the cooling system of the furnace using optimum cooling guides and fail-safe features are critical in order to improve the safety of the process. Regarding this, manufacturing of porous material with high electrical isolation for the drainage segments of the cooling channels is examined in this study. Consequently, various geometries with different porosities using glass and ceramic powder are fabricated using Selective Laser Sintering (SLS) process. The manufactured parts are examined in a prototype furnace testing and the feasibility of the SLS manufacturing of parts for this application is discussed.
Although laser-based Additive Manufacturing (AM) processes have been investigated extensively for use with different materials, fabrication of 3D glass objects using Selective Laser Melting (SLM) technology is not well developed even though it has many applications. As such an experimental investigation on the process parameters of glass powder using SLM process was conducted and the results are summarized in this paper. Multiple 3D objects were fabricated and analyzed. Lastly Scanning Electron Microcopy (SEM) of the manufactured objects as well as effect of process parameters on dimensional accuracy, surface quality, and the density of the fabricated parts are presented in this paper.
Direct selective laser sintering (SLS) or selective laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800̊C). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 μm were successfully produced.
Oxide ceramics yield excellent mechanical properties along with outstanding thermal and wear resistance. However, little work on additive Manufacturing (AM) of high-strength ceramics has been stated. In the present paper the current state of development in Selective Laser Melting (SLM) of pure ceramic specimens is reviewed. During the present approach the eutectic mixture of pure alumina (AhO3) and zirconia (ZrO2) powder is completely molten while crack formation is prevented by a high-temperature CO2-I aser preheating. This approach yields net-shaped, fully dense specimens reaching flexural strengths of above 500 MPa without post-processing. One potential application for this technology are fully-ceramic dental restorations frameworks, as the demanded maximum loads of above 1000 N are met. Alternative preheating strategies are presented to allow for manufacturing larger volumetric parts.
Thermally induced phase separation (TIPS) was used to produce spherical polypropylene-zirconia composite powder for selective laser sintering (SLS). The influence of the composition of the composite starting powder and the SLS parameters on the density and strength of the composite SLS parts was investigated, allowing realizing SLS parts with a relative density of 36%. Pressure infiltration (PI) and warm isostatic pressing (WIPing) were applied to increase the green density of the ZrO2-PP SLSed parts. Infiltrating the SLS parts with an aqueous 30vol.% ZrO2 suspension allowed to increase the sintered density from 32 to 54%. WIPing (135°C and 64MPa) of the SLS and SLS/infiltrated complex shape green polymer-ceramic composite parts prior to debinding and sintering allowed raising the sintered density of the 3mol Y2O3 stabilized ZrO2 parts to 92 and 85%, respectively.
Although process parameters of Selective Laser Melting (SLM) method have been established for different materials, fabrication of parts using SLM of glass powder has remained a challenge so far. This study presents a synopsis of an experimental investigation study on SLM of soda-lime glass powder. The process parameters are analyzed using various test geometries, and a set of optimized process parameters is determined and used to build multiple objects. The morphology and mechanical properties of the fabricated parts are analyzed. The results demonstrate the feasibility of SLM process to successfully build objects from soda-lime glass powder for different applications.
Considers efforts to date to produce parts by direct selective laser sintering (SLS) of metals, including post processing to improve structural integrity and/or to induce a transformation. Provides a brief overview of the basic principles of SLS machine operation, and discusses materials issues affecting direct SLS of metals and the resultant properties and microstructures of the parts. Reviews results of past efforts on SLS of metal systems such as Cu-Sn, Cu-Solder (Pb-Sn), Ni-Sn, pre-alloyed bronze (Cu-Sn). Finally discusses more recent efforts on SLS of bronze-nickel powder mixtures in greater detail.
Additive processes, which generate parts in a layered way, have more than 15 years of history. These processes are not exclusively used for prototyping any longer. New opportunities and applications in appropriate manufacturing tasks open up, even though the economical impact is still modest.This review starts with the definition of Rapid Manufacturing and Rapid Tooling, dealing only with direct fabrication methods of components. A systematic material dependent classification of layer manufacturing and process oriented metal part manufacturing techniques are proposed. The generic and the major specific process characteristics and materials are described, mainly for metallic parts, polymer parts and tooling. Examples and applications are cited.The paper attempts to understand the state of the art and the prospective, to put questions, to understand limits, to show opportunities and to draw conclusions based on the state of the art.
Layered manufacturing (LM) is gaining ground for manufacturing prototypes (RP), tools (RT) and functional end products (RM). Laser and powder bed based manufacturing (i.e. selective laser sintering/melting or its variants) holds a special place within the variety of LM processes: no other LM techniques allow processing polymers, metals, ceramics as well as many types of composites. To do so, however, quite some different powder consolidation mechanisms are invoked: solid state sintering, liquid phase sintering, partial melting, full melting, chemical binding, etc. The paper describes which type of laser-induced consolidation can be applied to what type of material. It tries to understand the underlying physical mechanisms and the interaction with the material properties. The paper demonstrates that, although SLS/SLM can process polymers, metals, ceramics and composites, quite some limitations and problems cause the palette of applicable materials still to be limited. There is still a long way to go in tuning the processes and materials in order to enlarge the applicability of LM. This is not surprising if one compares it to the decades of R&D work devoted to tuning processes and materials for hot or cold forming, metal cutting (e.g. development of free machining steels), casting and injection moulding (including powder injection moulding: MIM, CIM, etc.).
These Ecole polytechnique federale de Lausanne EPFL, n° 2506 (2002)Section de genie mecaniqueFaculte des sciences et techniques de l'ingenieurInstitut de production et robotiqueLaboratoire de gestion et procedes de productionJury: Jacques Giovanola, Paul-Eric Gygax, Jean-Pierre Kruth, Wilfried Kurz, Valerio Romano Public defense: 2002-2-25 Reference doi:10.5075/epfl-thesis-2506Print copy in library catalog Record created on 2005-03-16, modified on 2016-08-08
Door selectief laser sinteren / smelten (SLS/SLM) van Fe – Cu – Fe3+xP – Ni poeder werd de performantie van de beschikbare machines voor de productie van ijzergebaseerde objecten met hoge dichtheid geëvalueerd. Een tweede deel van deze studie handelt over het effect van procesparameters, legeringelementen (C, Si, Ti en Cu) en zuurstof op het gedrag van Fe tijdens selectief laser smelten (SLM).
In gepulste laser mode en bij een hoge laserintensiteit veroorzaakt verdamping van het materiaal een druk op het oppervlak van het smeltbad. Deze druk verbetert bij gematigde waarden de verdichting tijdens SLM. Voorwerpen met een dichtheid tot 95% werden geproduceerd uitgaande van Fe – Cu – Fe3+xP – Ni, Fe en Fe – C (0.2 –0.8 gew%) poeders. De stabiliteit van een ijzergebaseerd smeltbad tijdens SLM op een poederbed wordt in continue laser mode bepaald door de scansnelheid, het zuurstofgehalte in de atmosfeer en de aanwezige legeringelementen. Deze afhankelijkheid wordt hoofdzakelijk verklaard door het effect van deze factoren op de lengte tot diameter verhouding van het smeltbad en op de kinetica van Rayleigh instabiliteit. Een correlatie tussen enerzijds de oppervlaktemorfologie en de porositeit van driedimensionale stukken en anderzijds het effect van proces- en materiaalparameters op de fysische fenomenen die optreden tijdens SLM wordt voorgesteld. Er werd vastgesteld dat de warmtevrijgave als gevolg van oxidatie van Fe of van legeringelementen zoals C, Si of Ti in vele gevallen het gedrag van ijzergebaseerde poeders tijdens SLM bepaalt. Selective laser sintering/melting (SLS/SLM) of Fe – Cu – Fe3+xP – Ni powder is performed to evaluate the feasibility to manufacture iron-based parts with a high density. A second part focuses on the effect of process parameters, alloying elements (C, Si, Ti and Cu) and oxygen on the behaviour of Fe during selective laser melting (SLM).
In pulsed laser mode at high energy intensities strong evaporation of the material induces a recoil pressure that acts on the melt pool, facilitating the densification at intermediate pressure values. Parts with a density of up to 95% are produced from Fe – Cu – Fe3+xP – Ni, Fe and Fe – C (0.2 – 0.8 wt% C) powders.
The stability of an iron-based melt pool created during SLM in continuous laser mode on top of a loose powder bed is largely affected by the scan speed, the oxygen content in the atmosphere and alloying elements. This is mainly explained in terms of their effect on the aspect ratio of the melt pool and on the kinetics of Rayleigh instability.
A correlation between the surface morphology and porosity of three-dimensional parts on the one hand and the effect of process and material parameters on the physical phenomena during SLM on the other hand is proposed. The heat release during oxidation of Fe or of alloying elements such as C, Si or Ti has a large impact on the quality of a part after SLM. Afdeling Fysische materiaalkunde Departement MTM Faculteit Ingenieurswetenschappen Doctoral thesis Doctoraatsthesis
Understanding Additive Manufacturing
- A. Gebhardt
Additive manufacturing of zirconia parts by indirect selective laser sintering
- Gebhardt Deckersb
- Zhongying Zhanga
- Jean-Pierre Kruthb
- Jef Vleugelsa
Gebhardt, Understanding Additive Manufacturing, Hanser Publications, 42, Cincinnati, 2011.
3 Khuram Shahzada, Jan Deckersb, Zhongying Zhanga, Jean-Pierre Kruthb, Jef Vleugelsa,
Additive manufacturing of zirconia parts by indirect selective laser sintering, Journal of the
European Ceramic Society, 34, 2014,81-89.
A sub-process approach of selective laser sintering PhD thesis Ecole Polytechnique Federale de Lausanne Switzerland
- Karapatisp