scholarly journals Vibratory Powder Feeding for Powder Bed Additive Manufacturing Using Water and Gas Atomized Metal Powders

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3548
Author(s):  
Chad W. Sinclair ◽  
Ralf Edinger ◽  
Will Sparling ◽  
Amin Molavi-Kakhki ◽  
Chantal Labrecque
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Systems ◽  
Single Layer ◽  
Control Flow ◽  
Discrete Element Modelling ◽  
Layer By Layer ◽  
Metal Powders ◽  
Powder Bed ◽  
Ni Alloy ◽  
Feeding Technology

Commercial powder bed fusion additive manufacturing systems use re-coaters for the layer-by-layer distribution of powder. Despite the known limitations of re-coaters, there has been relatively little work presented on the possible benefits of alternative powder delivery systems. Here, we reveal a feeding technology that uses vibration to control flow for powder bed additive manufacturing. The capabilities of this approach are illustrated experimentally using two very different powders; a ‘conventional’ gas atomized Ti-6Al-4V powder designed for electron beam additive manufacturing and a water atomized Fe-4 wt.% Ni alloy used in powder metallurgy. Single layer melt trials are shown for the water atomized powder to illustrate the fidelity of the melt tracks in this material. Discrete element modelling is next used to reveal the mechanisms that underpin the observed dependence of feed rate on feeder process parameters and to investigate the potential strengths and limitations of this feeding methodology.

scholarly journals Detection of Typical Metal Additive Manufacturing Defects by the Application of Thermographic Techniques

Proceedings ◽  
2019 ◽  
Vol 27 (1) ◽  
pp. 24
Author(s):  
D’Accardi ◽  
Altenburg ◽  
Maierhofer ◽  
Palumbo ◽  
Galietti
Keyword(s):  
Additive Manufacturing ◽  
Processing Parameters ◽  
Layer By Layer ◽  
Metal Powders ◽  
Destructive Testing ◽  
Powder Bed ◽  
Manufacturing Defects ◽  
Metal Additive Manufacturing ◽  
Time Required ◽  
Metal Additive

One of the most advanced technologies of Metal Additive Manufacturing (AM) is the Laser Powder Bed Fusion process (L-PBF), also known as Selective Laser Melting (SLM). This process involves the deposition and fusion, layer by layer, of very fine metal powders and structure and quality of the final component strongly depends on several processing parameters, for example the laser parameters. Due to the complexity of the process it is necessary to assure the absence of defects in the final component, in order to accept or discard it. Thermography is a very fast non-destructive testing (NDT) technique. Its applicability for defect detection in AM produced parts would significantly reduce costs and time required for NDT, making it versatile and very competitive.

scholarly journals On The Relation Between Cooling Rate and Parts Geometry in Powder Bed Fusion Additive Manufacturing

2018 ◽  
Vol 1 (1) ◽  
pp. 223-231
Author(s):  
Nihat Yilmaz ◽  
Mevlüt Yunus Kayacan
Keyword(s):  
Additive Manufacturing ◽  
Cooling Rate ◽  
Solidification Process ◽  
Internal Stresses ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Powder Bed ◽  
Powder Particles ◽  
Manufacturing Technologies

Direct metal laser sintering (DMLS), one of the laser powder bed additive manufacturing technologies produces solid metal parts from 3-D CAD data, layer by layer, by melting/sintering and bonding metal powders with a focused laser beam. In this processes isn't complete melting of powder particles in micro melt pools as well as selective laser melting (SLM) and electron beam melting (EBM). Thus some different stress conditions and defects occur depending on the temperature changes during manufacturing. In this study, this problems is investigated aspect cooling rate. Cooling rate affects the solidification process in the melting (sintering) process such as casting, welding, laser assisted processes. Therefore, it also affect part quality and properties. In the scope of study, it is tried to explain how occurring the internal stresses and distortions differ depending on the cooling rates of geometrically different parts in additive manufacturing. The residual stresses and deformations are analyzed by FEA to see relation with geometry (volume, area) to cooling rate for Ti6Al4V materials. Cube shaped samples at 20, 40, 60, 80 and 100 mm edge dimensions have analysed by using FEA. Besides 10mm cube sample is manufactured as solid and verified both as experimental and numerical. Based on the FEA results, cooling rate values are changed from 1.67 to 16.67. In conclusion, the reasons of the problems occurring during laser powder bed fusion are investigated in terms of the cooling rate in relation with the samples geometry.

scholarly journals A STRUCTURED APPROACH TO REDUCE DESIGN ITERATIONS IN ADDITIVE MANUFACTURING

2021 ◽  
Vol 1 ◽  
pp. 231-240
Author(s):  
Laura Wirths ◽  
Matthias Bleckmann ◽  
Kristin Paetzold
Keyword(s):  
Additive Manufacturing ◽  
Spare Parts ◽  
Design Guidelines ◽  
Final Part ◽  
Layer By Layer ◽  
Powder Bed ◽  
Batch Sizes ◽  
Manufacturing Technologies ◽  
Structured Approach ◽  
Design Freedom

AbstractAdditive Manufacturing technologies are based on a layer-by-layer build-up. This offers the possibility to design complex geometries or to integrate functionalities in the part. Nevertheless, limitations given by the manufacturing process apply to the geometric design freedom. These limitations are often unknown due to a lack of knowledge of the cause-effect relationships of the process. Currently, this leads to many iterations until the final part fulfils its functionality. Particularly for small batch sizes, producing the part at the first attempt is very important. In this study, a structured approach to reduce the design iterations is presented. Therefore, the cause-effect relationships are systematically established and analysed in detail. Based on this knowledge, design guidelines can be derived. These guidelines consider process limitations and help to reduce the iterations for the final part production. In order to illustrate the approach, the spare parts production via laser powder bed fusion is used as an example.

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

Thermal conductivity of metal powders for powder bed additive manufacturing

2018 ◽  
Vol 21 ◽  
pp. 201-208 ◽  
Author(s):  
Lien Chin Wei ◽  
Lili E. Ehrlich ◽  
Matthew J. Powell-Palm ◽  
Colt Montgomery ◽  
Jack Beuth ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Additive Manufacturing ◽  
Metal Powders ◽  
Powder Bed

Additive Manufacturing of Nickel-Based Super Alloys for Aero Engine Applications

2020 ◽  
pp. 48-70
Author(s):  
Raja A. ◽  
Mythreyi O. V. ◽  
Jayaganthan R.
Keyword(s):  
Additive Manufacturing ◽  
Complex Geometry ◽  
Source Parameters ◽  
Raw Material ◽  
Layer By Layer ◽  
Powder Bed ◽  
Complex Design ◽  
Direct Energy ◽  
Second Phases ◽  
Metal Addition

Ni based super alloys are widely used in engine turbines because of their proven performance at high temperatures. Manufacturing these parts by additive manufacturing (AM) methods provides researchers a lot of creative space for complex design to improve efficiency. Powder bed fusion (PBF) and direct energy deposition (DED) are the two most widely-used metal AM methods. Both methods are influenced by the source, parameters, design, and raw material. Selective laser melting is one of the laser-based PBF techniques to create small layer thickness and complex geometry with greater accuracy and properties. The layer-by-layer metal addition generates epitaxial growth and solidification in the built direction. There are different second phases in the Ni-based superalloys. This chapter details the micro-segregation of these particles and its influence on the microstructure, and mechanical properties are dependent on the process influencing parameters, the thermal kinetics during the process, and the post-processing treatments.

scholarly journals Recent Studies and Developments in Titanium Biomaterials

2020 ◽  
Vol 321 ◽  
pp. 02004
Author(s):  
M. Ikedaa ◽  
M. Ueda ◽  
M. Ninomi
Keyword(s):  
Health Care ◽  
Additive Manufacturing ◽  
Titanium Alloys ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Layer By Layer ◽  
Metal Powders ◽  
Alloy Development ◽  
Dental Surgery ◽  
Artificial Bones

Titanium and its alloys have a high specific strength, excellent corrosion resistance, and good biocompatibility. Therefore, these alloys are adopted as raw materials for artificial bones and joints. Furthermore, these alloys are used as materials for dental surgery. In the development of alloy design, beta-type titanium alloys that possess a lower Young’s modulus than other types of titanium alloys, e.g., Ti-6Al-4V alpha-beta-type alloys, are being actively investigated worldwide. Based on these studies, titanium-niobium-tantalum and zirconium system alloys were developed. For example, Ti-29Nb-13Ta-4.6Zr alloy has a low Young’s modulus, excellent biocompatibility, and improved mechanical properties. Many researchers are actively investigating surface modifications and surface treatments. Additive manufacturing, namely 3D printing, wherein metal powders are piled up layer by layer to produce goods without a mold, has attracted attention in many fields, including manufacture of implants, especially porous structural implants with a low Young’s modulus. It is very important that titanium and its alloys be applied to health-care goods, e.g., wheelchairs and prostheses. Therefore, we herein consider four topics: alloy development, coating and surface modification, additive manufacturing, and health care applications.

Modeling, Simulation and Experimental Validation of Heat Transfer During Selective Laser Melting

2015 ◽  
Author(s):  
Mohammad Masoomi ◽  
Xiang Gao ◽  
Scott M. Thompson ◽  
Nima Shamsaei ◽  
Linkan Bian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mechanical Properties ◽  
Selective Laser Melting ◽  
Heat Fluxes ◽  
Transient Temperature ◽  
Thermal Gradients ◽  
Layer By Layer ◽  
Metal Powders ◽  
Laser Melting ◽  
Powder Bed

Selective Laser Melting (SLM), a laser powder-bed fusion (PBF-L) additive manufacturing method, utilizes a laser to selectively fuse adjacent metal powders. The powders are aligned in a bed that moves vertically to allow for layer-by-layer part construction-Process-related heat transfer and thermal gradients have a strong influence on the microstructural features, and subsequent mechanical properties, of the parts fabricated via SLM. In order to understand and control the heat transfer inherent to SLM, and to ensure high quality parts with targeted microstructures and mechanical properties, comprehensive knowledge of the related energy and mass transport during manufacturing is required. In this study, the transient temperature distribution within and around parts being fabricated via SLM is numerically simulated and the results are provided to aid in quantify the SLM heat transfer. In order to verify simulation output, and to estimate actual thermal gradients and heat transfer, experiments were separately conducted within a SLM machine using a substrate with embedded thermocouples. The experiments focused on characterizing heat fluxes during initial deposition on an initially-cold substrate and during the fabrication of a thin-walled structure built via stainless steel 17-4 powders. Results indicate that it is important to model heat transfer thorough powder bed as well as substrate.

scholarly journals Sensor-Based Additive Manufacturing Technologies

2021 ◽  
Vol 12 (3) ◽  
pp. 3513-3521
Keyword(s):  
Additive Manufacturing ◽  
Wearable Sensors ◽  
Sensor Technology ◽  
Layer By Layer ◽  
Environmental Sensors ◽  
Direct Energy Deposition ◽  
Powder Bed ◽  
Direct Energy ◽  
Building Components ◽  
Manufacturing Technologies

Additive manufacturing is the term that uses the CAD data to build components layer by layer; it is also termed layered manufacturing or 3D printing. The major advantage of additive manufacturing is the capability of building components without the use of molds or tools. Five major categories of AM processes include Powder Bed Fusion (PBF), Direct Energy Deposition (DED), Material Jetting (MJ), Binder Jetting (BJ), and Sheet Lamination (SL). The sensor may be defined as a device that responds to a physical stimulus and transmits a resulting impulse. Sensor technology has been widely adopted in advanced manufacturing, aerospace, biomedical and robotic applications. Commonly used sensors are temperature sensors, strain sensors, biosensors, environmental sensors, and wearable sensors, etc. Additive manufacturing technologies can fabricate sensors and microfluidic devices with less labor. This paper focuses on various sensors developed by additive manufacturing processes, and their practical application for the particular purpose is reviewed.

scholarly journals Vibrational Microfeeding of Polymer and Metal Powders for Locally Graded Properties in Powder-Based Additive Manufacturing

2021 ◽  
Author(s):  
R. Rothfelder ◽  
L. Lanzl ◽  
J. Selzam ◽  
D. Drummer ◽  
M. Schmidt
Keyword(s):  
Additive Manufacturing ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Experimental Setup ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Powder Bed ◽  
Frequency Excitation ◽  
Graded Properties ◽  
Contact Mechanical

AbstractSubject of this work is the contact mechanical properties and flowability of polymer and metal powders when they are dispensed on the surface of a powder bed for use in laser-based powder bed fusion in additive manufacturing. Generating local part properties in metal as well as polymer-based powder bed fusion processes is of high interest, so an approach is made to locally add additives by a vibrational microfeeding system for metal and polymer powders. To realize a controlled powder discharge, the behavior of additives, which are dropped on a surface and on a powder bed is analyzed. Influencing factors for mass flow of the powders will be excitation frequency, excitation amplitude and capillary diameter on the side of experimental setup as well as particle size distribution and physical properties on the material side.

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