Study on topology optimization design, SLM fabrication and performance of porous structure
Zhang, Dongyun; Xu, Yangli; Feng, Zhe;Zhang, Pudan; Cao, Xuanyang
The combination of topology optimization (TOP) and Selective laser melting (SLM) provides the possibility to fabricate
the complex, lightweight and of high performances of geometries. This paper evaluates the properties of porous
structure with different porosity (40%~80%) and unite cell size (2~8mm), which are designed by topology optimization
and explores their manufacturing limits for SLM. The compression properties, correlation between structural parameters
(unit cell size and porosity) and dynamic elastic modulus of porous structure were investigated in properties evaluation.
For manufacturing limits, three typical internal microstructures are abstracted and investigated including spiral
structure, arched structure and structure with thin wall and small holes. During the compression experiment, these
porous structures undergo catastrophic failure after forming crush band with an angle of 45°and their elastic modulus
and compressive strength decrease with increase of both porosity and unite cell size. Gibson-Ashby model is used to
evaluate the performance of porous structures, the value of structural parameter λ increases with the decrease of unite
cell size indicating better stability of structure. Finally, the model for correlation between porous structural parameters
and elastic modulus is established, which provides a mathematical reference for matching bone elastic modulus of
different age, gender and skeletal site of human race.
Keywords: selective laser melting, topology optimization, porous structure, elastic modulus , compression behavior
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Investigation of selective laser melting process dynamics for single- and multi-beam strategies using high speed imaging
Heeling, Thorsten; Gerstgrasser, Marcel; Wegener, Konrad
Selective laser melting is one of the most promising technologies for the additive manufacturing of near-fully dense
metal parts of very high complexity. Since the process still needs improvement in terms of repeatability, robustness and
quality an increasing number of possible strategies are proposed to do so. But because of the high speed and small scale
of the melt pool the process dynamics are mainly known from simulation models that neglect stochastic phenomena, so
that improvements are discussed based on an idealized understanding. Therefore this paper tries to make aware of the
processes’ randomness using high speed imaging, enabling a look into the dynamics of single-beam as well as innovative
multi-beam processing of stainless steel 316L. A focus is placed onto the difference in spatter characteristics because the
spatter leads to random errors within the parts that are unpreventable to a certain extent but are directly influencing
the resulting part’s quality.
Keywords: Spatter Characteristics; Multi-beam Strategies; High Speed Imaging; Selective Laser Melting; Additive Manufacturing
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Use of additive manufacturing for high-throughput material development
Vetter, Konstantin; Hohenäcker, Sven; Freiße, Hannes; Vollertsen, Frank
Discovering new metallic alloys based on a high-throughput method as known from life sciences would reduce the effort
of experimental investigations as well as the use of resources. The realization of reproducibly homogeneous alloy
compositions is required to implement such a novel method in order to provide materials with a precisely adapted
requirements profile. In this work, a process chain of two laser-based processes under the application of additive
manufacturing is presented. Powdered stainless steel is applied on an unalloyed case hardening steel by selective laser
melting (SLM), before base material and master alloy is remelted and mixed using a modulation form of consecutive
overlaying circles. The application of different laser power and modulation speed leads to graded melt pools of different
size and shape. It can be shown that micro samples can be produced with a sufficient melt pool size without pores and
cracks.
Keywords: selective laser melting; laser deep alloying; material development
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Experimental and theoretical analysis of thermo-optical effects in protective window for selective laser melting
Bonhoff, Tobias; Schniedenharn, Maximilian; Stollenwerk, Jochen; Loosen, Peter
The objective of this work is to study thermo-optical effects in protective windows for selective laser melting. Therefore,
an interface to couple finite element analysis and wave-optical analysis is used. The laser beam caustic is analyzed for
three different protective window materials, fused silica, N-BK7, and N-FK51A. The impact of contamination of the
window by metal plume is investigated experimentally and theoretically. The simulations predict the highest focus shift
for a contaminated fused silica window whereas N-FK51A has nearly no impact on the beam caustic due to its
athermalized behavior. The experimental results reveal that an increasing contamination is accompanied by an
increasing focus shift and a decreasing beam quality.
Keywords: selective laser melting; thermal lensing; protective window; finite elemente analysis
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A fluid-dynamic numerical model for the selective laser melting of high-thickness metallic layers
Cordovilla, Francisco; Garzón, Miguel; Muñoz, Diego Alejandro; Diaz, Javier; García-Beltrán, Ángel; Ocaña, José Luis
Productivity in the Selective Laser Melting Process (SLM) is directly related with the thickness of the powder bed that is
repeatedly applied, at every increment, in the growing of consolidated material in the additive manufacturing process.
Although most of the relevant phenomena (limited diffusivity associated to particles contact, phase changes, gradients
of surface tension associated with Marangoni convection, or even recoil pressure) are considered in the models with
small bed thicknesses (roughly 20 μm – 40 μm), in the case of larger thicknesses (between 100 μm and 200 μm) these
factors strongly influence the size and shape of the fusion bath leading to a non trivial geometry of the final consolidated
material. The present work proposes the use of the Arbitrary Lagrangean-Eulerian method (ALE method) to solve the
thermal and Navier-Stokes equations in the frame of a free-moving discretization to predict simultaneously the space-
time temperature evolution and the associated fusion bath dynamics. It allows for using a continuous domain to
represent the powder bed, which, instead of a particle model approach, is advantageously compatible with realistic
process parameters, where long paths are covered by the laser. The model was validated with experimental data using
Inconel as working material, showing a good degree of agreement.
Keywords: SLM; ALE Method; Marangoni Convection; Fluid Dynamics
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Selective laser melting of copper using ultrashort laser pulses
Kaden, Lisa; Matthäus, Gabor; Ullsperger, Tobias; Tünnermann, Andreas; Nolte, Stefan
Laser assisted additive manufacturing has attracted a lot of attention during the last decade due to the possibility of
creating three-dimensional freeform structures with almost any desired geometry. Selective laser melting using the so-
called powder bed method is one of the most established among many laser manufacturing approaches, especially for
metal based products. Nowadays, CW and long pulse lasers are commonly used for additive manufacturing technologies. Recently, the application of ultrashort pulse lasers came into focus. In particular, these lasers provide extremely high
peak power and offer the potential to control the thermal spreading in the vicinity of the focal region by tailoring the
laser parameters. Therefore, also the processing of materials with extraordinary high melting points or the application of
new composites come into reach. Additionally, based on the ultrashort pulse durations which are several orders of
magnitudes shorter than any thermal relaxation processes the exploitation of thermal non-equilibrium regimes by using
extremely fast cooling rates enables the generation of new material systems and the fabrication of highly resolved
geometric structures. Here, we present selective laser melting of copper by using ultrashort laser pulses with 500 fs pulse duration at a center
wavelength of 1030 nm. Suitable processing windows have been identified by performing a detailed parameter study.
Bulk and thin wall copper parts could be realized by ultrashort selective laser melting.
Keywords: additive manufacturing; selective laser melting; selective laser sintering; ultrashort laser pulses; laser micro processing;
copper
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Deterministic defect generation in selective laser melting: parametric optimization and control
Andreau, Olivier; Peyre, Patrice; Penot, Jean-Daniel; Koutiri, Imade; Dupuy, Corinne; Pessard, Étienne; Saintier, Nicolas
Selective Laser Melting (SLM) is a powder based additive manufacturing process where parts are made layer-by-layer
from a 3D file (STL). The complexity of a part is not a barrier in SLM, and thus the process opens new doors to design and
elaborate intricate and complex shapes. This study focuses on the deterministic defect/pore generation SLM –i.e. leaving
precisely unmelted powder zones in an SLM part on purpose. In order to get a high accuracy and part reproducibility, a
thorough parametric optimization is required, especially for the laser contour scan, which determines both the
roughness outside a part and the geometry inside a deterministic defect. Different sets of parameters must be used for
the contour and hatch scans, in order to obtain a minimum porosity amount in the solid area while getting a minimal
deformation around the pores. The deterministic pore generation gives new tools to characterize and develop new NDT
techniques or simulate casting defects. Those pores could also be integrated in novel multifunctional materials, to
implement damage detection (structural health monitoring) or to attain better thermal properties while still keeping
good mechanical performances.
Keywords: SLM; Contour; Pore; Defect; NDT
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In situ and real-time monitoring of powder-bed AM by combining acoustic emission and machine learning
Wasmer, Kilian; Kenel, Christoph; Saeidi, Fatemeh; Leinenbach, Christian; Shevchik, Sergey A.
Until recently, additive manufacturing quality control has been diligently based on temperature measurements of the
process zone or layer-by-layer high resolution imaging. For this, various sensors such as pyrometers, photo-diodes and
matrix CCD detectors were involved. However, temperature measurements do not provide information about the heat
transfer in depth thus reducing the reliability of this method. High resolution imaging controls the quality post factum,
after a layer or even an entire part is already manufactured. No methods are known so far to monitor the quality of
additive manufacturing in situ and in real-time with high confidence. Our approach is to monitor the quality of the
additive manufacturing process in situ and in real-time by means of acoustic emission, detected by fiber optical sensors. It is shown that the melting and sintering process have a number of unique acoustic signatures that can be detected and interpreted in terms of quality. The combination of such acoustic signatures is related to heat distribution and process dynamics inside the processing zone. The interpretation of AE in terms of process quality is made by machine learning. This includes the extraction and recognition of unique acoustic signatures from the different sintering or melting events and further classification of those. The processing parameters for selective laser melting of a 316L stainless steel were tuned to create a cube with separate sections of three quality levels. The corresponding AE data was acquired; the acoustic features were extracted and classified according to the different qualities. The confidence level achieved in the classification was as high as 83-89%
showing that this methodology has a big potential for in situ and real-time monitoring in additive manufacturing process. The technical realization of the methodology presented is flexible and it can be easily integrated in any existing commercial additive manufacturing machine (as a hardware and/or software) as an additional module.
Keywords: Additive manufacturing; quality control; acoustic emission; fibre optical sensors; machine learning;
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Influence of SLM process parameters on Inconel 625 superalloy samples
De Terris, Thibaut; Adamski, Frédéric; Peyre, Patrice; Dupuy, Corinne
Selective Laser Melting (SLM) is an additive manufacturing technology which allows to create mechanical parts by
superimposing layers of selectively-fused metal powder one over the other. The current study is carried out in the frame
of FAIR project, leaded by Air Liquide Company, with the objective of manufacturing by SLM and certifying a prototype
of exchanger-reactor. A number of SLM trials were carried out on simple geometries or channeled samples to optimize the SLM process (laser
power, scan speed, focus spot, building strategy ...), with the first objective to generate samples combining a minimum
of porosity with as good as possible surface finish, while respecting a good geometrical accuracy. This objective was
mostly reached on simple cubic and channeled samples.
Keywords: Additive manufacturing ; Selective Laser Melting ; Inconel 625 superalloy ; Parameters optimization ;
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Processing of a high-strength Al-Fe-Ni alloy using laser beam melting and its potential for in-situ graded mechanical properties
Mohr, Gunther; Johannsen, Jan; Knoop, Daniel; Gärtner, Eric; Hummert, Klaus; Claus, Emmelmann
Laser beam melting (LBM) is a promising manufacturing technology for production of lightweight high quality parts. Due
to the layer-wise fusion of metallic powder it offers outstanding opportunities for topology optimised designs and
complex structures. One of the key challenges for further expansion of additive manufactured applications is to broaden
the spectrum of suitable materials for the process. Especially within the class of aluminium alloys there is a lack of
suitable high-strength alloys complementing prevalent aluminium-silicon casting alloys such as AlSi10Mg or AlSi12. The
paper portrays the successful LBM processing of a high-strength Al-Fe-Ni alloy, which is usually used by extrusion in
conventional manufacturing. In addition to the development of applicable process parameters for the production of
high-density and crack free samples, mechanical properties are presented. Furthermore, the microstructure is discussed.
Finally, the potential for manufacturing structures with graded mechanical properties is demonstrated by samples with
particular gradients of hardness dependent on processing parameters.
Keywords: Additive Manufacturing (AM); Selective Laser Melting (SLM); Laser Beam Melting (LBM); high-strength aluminium alloys;
metal powder
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Experimental investigation of a process chain combining sheet metal bending and laser beam melting of Ti-6Al-4V
Butzhammer, Lorenz; Dubjella, Patrick; Huber, Florian; Schaub, Adam; Aumüller, Markus; Baum, Alexasnder; Petrunenko, Oleksandra; Merklein, Marion; Schmidt, Michael
In spite of several advantages such as a great freedom of design, comparatively long process times are a major drawback
in additive manufacturing technologies such as laser beam melting (LBM) of metal powder. A strategy to overcome this
limitation is to combine additive manufacturing with other promising manufacturing concepts. In this paper, we characterize hybrid components manufactured using a consecutive process chain including warm bending of Ti-6Al-4V sheets and LBM. With the additive process a functional structure is built on top of the bending zone using powder from the same material. As a measure for the connection strength, shear tests were performed. The shear strength is analyzed for both possible process routes of forming and LBM. Therefore a modular clamping device for bent sheets was developed in order to enable simultaneous production of additive parts on several bent sheets with different thicknesses and radii. Results show that the formability of sheets is strongly influenced by the sequence of the process route, while no significant difference in shear strength of the connection was observed, even if the energy density in the LBM process is varied to a large extent. The post heat treatment is discussed as major cause, as homogenization of the microstructure takes place, although the applied temperature is beneath the beta transus temperature.
Keywords: Laser Beam Melting; Additive Manufacturing; Bending; Titanium Alloys
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Monitoring of powder flow dynamic behavior in LMD processes by high speed imaging.
Montero, Javier Nicolás; Rodriguez, Ángel; Amado, José Manuel; Tobar, María José; Yáñez, Armando
In laser metal deposition processes the interaction between the powder particles and the melt pool has a direct effect
over the bead quality and part dimensional accuracy. This fact makes important the study of powder beam particle
distribution and particle speed to ensure their values are kept under acceptable limits. Those quantities, however, can
change with time during the equipment operation or be subjected to perturbations. Dynamic behavior of the solid phase
flow is difficult to determine and in most cases it is not studied. To address this issue a monitoring system based on high
speed imaging of the powder particles is presented. This monitoring system is able to record changes in the powder
mass flow rate and powder distribution by sampling particle crossings in a row of pixels during a fraction of a second.
Real time monitoring can be achieved to detect flow perturbations or misalignment of the LMD head.
Keywords: Powder technology; Laser metal deposition; Lase Cladding; Hight-speed monitoring;
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Comprehensive analysis of SLM of TiAl powder
Doubenskaya, Maria; Domashenkov, Alexey; Smurov, Igor; Petrovskiy, Pavel
Selective laser melting of intermetallic Ti–48Al–2Cr–2Nb powder is studied using parametric analysis, metallography,
optical diagnostics and mathematical modeling. Two substrate materials are compared: Steel S235 and pure Al.
Preheating up to 450 °C is applied for manufacturing of cubic samples. Resulting porosity versus processing parameters
is analyzed. The average microhardness of the manufactured samples varies in the range of 540-559 HV0.3. XRD analysis shows prevailing of the α2-Ti3Al phase in the initial powder, heat treated powder and developed samples.
Some minor peaks of γ-TiAl appeared in SLM processed specimens. EDS analysis shows the effect of Al evaporation,
which intensifies with laser input energy. The IR-camera is used for optical diagnostics of a single track formation. The geometry of heat affected zone versus processing parameters is analyzed. The evaporation of Al is detected by IR-camera for the elevated laser energy. Mathematical modeling reveals that the same region of a sample can be remelted several times during fabrication,
depending on the SLM processing parameters and strategy of beam scanning. The maximum calculated cooling rates are
of the order of 106 °C/sec.
Keywords: Selective Laser Melting, intermetallics, optical diagnostics, Al evaporation, thermo-cycling.
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Laser based post processing of additive manufactured metal parts
Hofele, Markus; Schanz, Jochen; Burzic, Bahrudin; Lutz, Simon; Merkel, Markus; Riegel, Harald
Additive manufacturing (AM) techniques, like powder-bed based Selective Laser Melting (SLM), are gaining in
importance which leads to a continuously increasing market. The SLM process offers the opportunity to generate highly
complex solid metal parts, with low porosity and good mechanical properties. However, the layer-wise production
process has also certain disadvantages, like a relatively high surface roughness with fluctuations depending on
component shape, position and orientation during the fabrication process. Therefore, there is a demand for post
processing methods offering similar design flexibility as the SLM process itself. Laser based post processes of additive
manufactured parts like laser cleaning and laser polishing provides the possibility of a contact-free and full-automatable
surface treatment of metal alloys with short processing times. This paper deals with the investigation in laser cleaning and the development of laser polishing of SLM parts made of steel or aluminum. Laser cleaning with an ns-pulsed fibre laser leads to effective ablation of residual metal powder on
the rough topography of the SLM surfaces and a significant reduction of the oxide layer. Laser polishing revealed a
reduction of the surface roughness of greater than 95%, i.e. from a Ra-value of 8.7 μm on AlSi10Mg (initial state) to a Ra-
value of 0.2 μm or lower (final state) and on X2CrNiMo17-12-2 steel (1.4404) from a Ra value of 12.5 μm down to 0.35
μm at a process rate of up to 35 cm2/min. Polishing strategies with one and multiple crossings are investigated. Several
test series with pulsed wave (pw) and continuous wave (cw), with variation of laser parameters like laser spot diameter,
beam intensity or the feed rate have been investigated.
Keywords: Additive manufacturing, Selective Laser Melting (SLM), stainless steel 1.4404, Aluminum AlSi10Mg, Surface cleanliness, Laser
Cleaning, Laser Polishing, Surface Quality
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Geometrical and topological potentialities and restrictions in selective laser sintering of customized carbide precision tools
Schwanekamp, Tobias; Bräuer, Markus; Reuber, Martin
The joint research project PraeziGen is dedicated to achieve a technology leap by applying additive manufacturing (AM),
respectively selective laser sintering (SLS) or melting (SLM), to fabricate customized carbide precision tools with complex
inner and outer shape. A main objective during the project is the development of a process chain for AM of near-net-
shape cutting tools and the qualification of carbide materials, especially tungsten carbide (WC-CO), for the SLS process.
The increased design freedom inherent to AM processes offers significant benefits with respect to the development of
cutting tools, such as a light-weight design and an increased degree of functionality. The ability to fabricate customized
cooling channel systems inside the tool is of particular interest for industrial applications. Those applications are
currently limited to the processing of steel alloys and have not been published for WC-Co so far. This is mainly caused by
the intrinsic issues in SLS of tungsten carbide such as the formation of pores, cracks and brittle material phases, which
were already identified in several studies. However, for the design of tools with complex shapes, not only the material
microstructure and quality, but also the process-related geometrical and topological restrictions are of utmost
importance. For example, the surface roughness inside the generated cooling channel has a significant impact on the
pressure losses and the flow rate of the coolant. For SLM/SLS-qualified materials such as steel or aluminum alloys,
appropriate design guidelines have already been established to consider the specific characteristics of the additively
manufactured parts. Distinct guidelines for WC-Co are not yet existing and have to be elaborated. Hence, the proposed
paper deals with the study of the geometric and topologic design aspects in SLS of WC-Co with regard to the
characteristic design features of application optimized cutting tools.
Keywords: Selective Laser Sintering (SLS); Selective Laser Melting (SLM); Tungsten Carbide (WC-Co); Cutting Tools; PraeziGen; Design
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Affecting Transmission NVH-Behavior by Implementing a Damping System Using Additive Manufacturing
Schmitt, Matthias; Kamps, Tobias; Seidel, Christian;Reinhart, Gunther
Additive manufacturing, especially powder bed-based technologies, like Laser Beam Melting (LBM), provides a suitable
technology for manufacturing complex parts. This permits an innovative product design for resource efficiency and
effectiveness via lightweight design or functional integration. To exploit this potential, the presented project focuses on improving the NVH (Noise, Vibration, Harshness)-behaviour of gear transmissions by implementing particle damping into a gear wheel through additive manufacturing. Particle damping is widely used in the suppression of vibration in translational motions, but is less described for the use in circular motions. Nevertheless, there are reports qualifying the effectiveness of particle damping in gear wheels. Kinetic energy is dissipated through inelastic collisions and friction between the particles, there by making particle damping a passive technology for vibration reduction. The efficiency of particle damping is determined by various parameters. Those include powder material density, size and form of particles, number and form of cavities and filling rate of such cavities. LBM is a suitable production te chnology to manufacture gear wheels with particle damping due to the offered design freedom and due to the possibility of including particles in closed cavities as a result of the layer-by-layer production principle. Within this contribution, a method to include particle damping in gear wheels via additive manufacturing is described .
Variated particle sizes will be determined and the feasibility for particle damping will be rated. As a second step , the
issue of extracting remaining powder in the cavities will be addressed. Furthermore, a rating of possible cavity forms will
be shown. The results are graded in order to show the manufacturability of particle damping systems using additive
manufacturing.
Keywords: additive manufacturing; laser beam melting; gear wheel; NVH- behaviour; particle damping
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Selective Laser Melting of NiTi powder
Domashenkov, Alexey; Doubenskaya, Maria; Smurov, Igor; Smirnov, Maxim; Travyanov, Andrew
Selective laser melting (SLM) is applied to develop samples from NiTi powder using preheating up to 600°C (to reduce
thermal gradients) and different substrate materials: 304L, Ti-6Al-4V, Inconel 718. It is found that the composition of
substrate influences the resulting porosity and eventual cracking of NiTi layers. The principle phase of the obtained
samples is NiTi B2 austenite. Some minor picks of R martensite are detected, as well as the formation of Ni4Ti3
precipitates. The microstructure of the samples is austenitic with martensite-like zones of the R phase. Martensitic
structure is found inside the cracks. Mechanical properties are measured by nanoindentation: Young's modulus of B2
austenite is 108 GPa and the hardness is equal to 8.1 GPa; for R martensite Young's modulus is 84.1 GPa and the
hardness is equal to 5.7 GPa.
Keywords: selective laser melting, intermetallics; Nitinol, nanoindentation, mechanical properties
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Study of resistance of stainless steels manufactured by selective laser melting to pitting and crevice corrosion
Mushnikova, Svetlana; Parmenova, Olga; Kuznetsov, Pavel; Krasikov, Aleksey; Staritsyn, Mikhail
Pitting and crevice corrosion resistance of martensitic (AISI 410L) and austenitic (AISI 316L) stainless steels manufactured
by selective laser melting was studied. Corrosion resistance was evaluated by ASTM G 48 test method with 10%
FeCl3·6H2O solution. Unusual increase of stainless steels tendency to pitting and crevice corrosion was revealed after surface machining of
specimen, probably because of removing of dense surface layer and the subsurface pores opening. There is shown that
heat treatment reduced negative influence of surface machining by dissolving chromium carbides. As a result, corrosion
losses are decreased and pitting amount reduce is observed.
Keywords: stainless steel, selective laser melting, pitting corrosion, crevice corrosion;
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Manufacturing, microstructure and mechanical properties of selective laser melted Ti6Al4V-Cu
Kinnear, A.; Dzogbewu, T.C.; Krakhmalev, P.; Yadroitsava, I.
Ti6Al4V is a commonly used biomedical alloy because of its suitable mechanical and biocompatible properties. Infection
at the bone–implant interface is the most probable reason for implant failure directly after implantation. Copper is a
proven anti-bacterial agent and in small amounts is not toxic to the human body. Copper additions reduce the risk of
bacterial infection and implant failure. Thus advanced implants can be constructed to have a biocompatibility and
antibacterial properties. Optimal process parameters are needed to be established for in-situ alloying of Ti6Al4V-Cu to
form dense parts with suitable mechanical properties. The effect of laser scanning speeds and hatch distance on
morphology of single layers was investigated. The surface roughness, chemical composition and distribution of Cu near
the surface and within the synthesized layer, as well as micro hardness were considered. An employed rescanning
strategy showed improved alloy homogeneity and surface quality. On the base of these data 3D samples were produced.
Microstructure and mechanical properties of as-built parts were analysed.
Keywords: Ti alloys; implants; antibacterial properties; microstructure
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Selective laser sintering/melting of multi-material parts
Chivel, Yuri
New method for 3D multi-material parts production has been elaborated. SLM machine concept and concept of the
build platform cleaning system is presented and discussed. Metodology of the multi-material object sintering is proposed for better accuracy of 3D object production having regards to shrinkage and dissolution . Results of experimental investigations of material cross - contamination are presented.
Keywords: multi-material parts, selective laser melting, cleaning system, dissimilar material, particles diameter.
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Additive technology of ceramic turbomachines manufacturing
Sudarev, Anatoly; Konakov, Vladimir; Chivel, Yuri
New nanostructured ceramic powders based on SiC-Si(BN) - Al2O3 system for laser sintering were elaborated. Investigations of ceramic
material have been conducted. Ceramics obtained by selective laser sintering followed by thermal treatment is 3-5 times less massive
than metallic and is sufficiently compact for applications as a constructional material for microturbine production. Microturbine
components produced and tested are presented.
Keywords:; nanostructured ceramic;selective laser sintering,;ceramic turbomachine;non-shrinkage cermet.
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Optimization of laser welding process for laser additive manufactured aluminum parts by means of beam oscillation and process-oriented component design
Beckmann, Frank; Emmelmann, Prof. Dr.-Ing. Claus
This paper deals with laser beam welding of laser additive manufactured (LAM) aluminum components. Experimental
results are presented, as by means of beam oscillation, the increased seam porosity can be reduced during the laser
beam welding of such components. Furthermore, due to the layered manufacturing process, LAM components have
particular geometric and surface properties. The second part of the paper presents how this affects the laser welding
process.
Keywords: Additive manufacturing, laser welding
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Single crystal microstructure built by Selective Laser Melting
Chen, Jiachun; Schwarze, Dieter; Niendorf, Thomas
Among metal additive manufacturing technologies, Selective Laser Melting (SLM†) is a highly developed and widely
used processing method. Products of arbitrary shape can be built directly from CAD data. In recent years, many groups
have worked on development of processing strategies, mainly aiming at high density, decrease of defect size and
smooth surfaces. Until today little has been done on design of microstructures in the products. By applying suitable
processing parameters and laser sources, microstructure can be directly tailored. This work reports single crystal
microstructure in INCONEL‡ 718 specimens produced with a selective laser melting machine. The Machine was re-
constructed and a laser with internal developed laser beam profile is equipped. Processing strategies and parameters
were developed to obtain the single crystal microstructure in the built parts. Based on the results shown, SLM Solutions
created methods to build or repair components with single crystal microstructure with SLM technology, which can be
utilized for example in the aircraft engine industry.
Keywords: Selective laser melting, Single crystal, INCONEL 718, Microstructure;
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Effect of baseplate temperature on molten titanium particle for development of sputter-less SLM
Sato, Yuji; Tsukamoto, Masahiro; Shobu, Takahisa; Yamashita, Yorihiro; Yamagata, Shuto; Higashino, Ritsuko; Masuno, Shinichiro; Abe, Nobuyuki
Dynamics of molten titanium irradiated with laser was investigated experimentally by a synchrotron radiation analysis;
because it is important to analyze a process of a molten metal for a 3D material fabricated by a selective laser melting
(SLM), such as one of additive manufacturing technology. A contact angle with molten titanium was measured by
synchrotron radiation at 30 keV while the laser irradiation. The size of Ti particle and laser spot diameter was same as
200 micro-meters. The Ti particle was place on the SUS304 substrate in a vacuum chamber. The chamber was evacuated
at the pressure of 1 Pa. In this condition, the laser was vertically irradiated on the Ti particle. A baseplate temperature
was varied from 25 to 500 degree Celsius. As the results, the baseplate temperature was increase with decrease the
contact angle. At the baseplate temperature of 500 degree Celsius, the contact angle with molten Ti became small to 32
degrees.
Keywords: Selective laser melting, synchrotron radiation, dynamics of molten metal
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Selective laser melting of AlSi40 using ultrashort laser pulses for additive manufacturing applications
Ullsperger, Tobias; Matthäus, Gabor; Kaden, Lisa; Rettenmayr, Markus; Risse, Stefan; Tünnermann, Andreas; Nolte, Stefan
The additive manufacturing of specific material compositions like hypereutectic alloys reveals fundamental problems. In
particular, during the fabrication with continuous wave lasers, the cooling rate is too low, resulting in a decomposition of
the different material components and a limited precision due to the increased melting zone, respectively. In this work
we demonstrate the selective laser melting of hypereutectic AlSi40 using 500 fs laser pulses at a wavelength of 1030 nm.
A controlled heat accumulation was utilized to address different melting regimes. It was possible to reduce the structure
size down to 50μm which is basically only limited by the grain size and layer thickness. Moreover, ultrashort laser pulses
allow melting and re-solidification on extremely short timescales which leads to a non-thermal equilibrium processing.
As a consequence, a more homogeneous micro-structure of AlSi40 can be demonstrated.
Keywords: Selective laser melting; Additive manufacturing; Light-weight structures; Ultra-short laser pulses; Hypereutictic alloys.
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Investigations on laser-based hot-melt bonding of additive manufactured plastic parts to metal sheets for strong and tight multi-material joints
Amend, Philipp; Laumer, Tobias; Baat, Florian; Roth, Stephan; Schmidt, Michael
In this paper, first results regarding the realization of laser-based hot-melt bonding of additive manufactured plastics
parts to metal sheets for strong and tight multi-material joints are presented. Compared to earlier investigations, in
which nearly solely extruded plastic materials were applied, the use of additive manufactured plastics complements the
research field with a promising approach. Besides the typical advantages of multi-material joints regarding weight
reduction and high strengths, such parts can meet the needs of constructional freedom and the avoiding of tool costs.
Materials used for this paper are aluminum (AlMg3), stainless steel (1.4301) and polyamide 12 (PA12). The performed
experiments resulting in multi-material joints between metal and polyamide. The realized specimens undergo a tensile
shear test and a tightness test, in which the characteristics of the joints are determined.
Keywords: Laser-based hot-melt bonding; multi-material joint; additive manufacturing
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Additive Manufacturing (AM) is increasingly moving into factories. To promote its industrialization, this contribution
analyses cost and lead time performance of AM factories. The performance impact of different production programs is
identified by varying order inflow and post processing sequence. Only under restricted conditions, the factory
performance allows novel approaches such as on demand manufacturing. To widen up these restrictions, organizational
and technical improvement measures are proposed.
Keywords: Additive manufacturing; Digital Direct Manufacturing; Factory configuration; Manufacturing systems; 3D printing;
Industrialization; Discrete event simulation
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Influence of laser power fluctuations on the quality of additive manufactured workpieces
Heinl, Martin; Galovskyi, Bogdan; Bayer, Florian; Laumer, Tobias; Hausotte, Tino
There is a great potential in selective laser sintering (SLS) processes caused by increasing application a reas in the field of
additive manufacturing (AM). The related requirements to the quality of additive manufactured workpieces can be
attributed to its process parameters . In this context, the examination of laser power fluctuations is interesting because of
its direct influence on the workpiece quality. If the planar energy input into the powder bed is not constant, local areas can
melt inhomogeneously beside the expected gauss-distributed intensity profile of the laser spot. For quality assessment a
testing workpiece and its manufacturing strategy have been developed to measure the interactions between laser power
and dimensional accuracy. Initially the appearing losses of the laser power in the beam path have been observed to
optimize the energy input. In addition to the warm-up behaviour of the CO2-laser, appearing energy peaks during short-
term sequences also show an influence on the workpiece quality. Finally in po t-process quality assessment, the
correlations of laser power with the dimensional accuracy and surface roughness are analysed by optical fringe projection
and focus variation technique.
Keywords: CO2-Laser, selective laser sintering (SLS), energy input, laser power fluctuation, dimensional deviation