scholarly journals Beamless Metal Additive Manufacturing

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 922 ◽  
Author(s):  
Mohammad Vaezi ◽  
Philipp Drescher ◽  
Hermann Seitz
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Sintering ◽  
Metal Powders ◽  
Metal Additive Manufacturing ◽  
Wide Range ◽  
Anisotropic Mechanical Properties ◽  
High Production ◽  
High Production Cost ◽  
Am Processes ◽  
Metal Additive

The propensity to manufacture functional and geometrically sophisticated parts from a wide range of metals provides the metal additive manufacturing (AM) processes superior advantages over traditional methods. The field of metal AM is currently dominated by beam-based technologies such as selective laser sintering (SLM) or electron beam melting (EBM) which have some limitations such as high production cost, residual stress and anisotropic mechanical properties induced by melting of metal powders followed by rapid solidification. So, there exist a significant gap between industrial production requirements and the qualities offered by well-established beam-based AM technologies. Therefore, beamless metal AM techniques (known as non-beam metal AM) have gained increasing attention in recent years as they have been found to be able to fill the gap and bring new possibilities. There exist a number of beamless processes with distinctively various characteristics that are either under development or already available on the market. Since this is a very promising field and there is currently no high-quality review on this topic yet, this paper aims to review the key beamless processes and their latest developments.

Design and Modeling of a Microscale Selective Laser Sintering System

2016 ◽  
Author(s):  
Nilabh Roy ◽  
Anil Yuksel ◽  
Michael Cullinan
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Feature Size ◽  
Powder Bed ◽  
Metal Additive Manufacturing ◽  
Wave Nature ◽  
Field Radiation ◽  
Metal Additive

The development of micro and nanoscale additive manufacturing methods in metals and ceramics is important for many applications in the aerospace, medical device, and electronics industries. Unfortunately, most commercially available metal additive manufacturing tools have feature-size resolutions of greater than 100 μm, which is too large to precisely control the microstructure of the parts they produce. A few research-grade metal additive manufacturing tools do exist, but their build rate is generally too slow for commercial applications. Therefore, this paper presents a new microscale selective laser sintering (μ-SLS) that can be used to improve the minimum feature-size resolution of metal additively manufactured parts by up to two orders of magnitude, while still maintaining the throughput of traditional additive manufacturing processes. In order to achieve this goal, several innovative design features like the use of (1) ultra-fast lasers, (2) a micro-mirror based optical system, (3) nanoscale powders, and (4) a precision spreader mechanism, have been implemented. The micro-SLS system is capable of achieving build rates of approximately 1 cm3/hr while achieving a feature-size resolution of approximately 1 μm. This paper will also present new molecular scale models that have been developed for the micro-SLS to quantify and certify the micro-SLS build process. Modeling of the micro-SLS process is challenging, because most macroscale models of the SLS process contain assumptions that are no longer valid when the size of the particles that are being sintered is smaller than the wavelength of the laser being used to sinter them. Therefore, in modeling the micro-SLS process we must account for the wave nature of light and can no longer rely on the ray tracing models commonly used to model the SLS process. Also, heat transfer in the micro-SLS process is dominated by near-field radiation due to the diffraction of the light off the nanoparticles in the powder bed and the ultrafast lasers that are used in the micro-SLS system. This means that the assumptions of heat transfer by conduction and far-field radiation in the macroscale SLS systems are no longer valid for the micro-SLS system. Finally, the agglomeration of nanoparticles in the powder bed must be accurately modeled in order to precisely predict the formation of defects in the final parts produced. Overall, the goal of this modeling effort is to be able to predict the quality of a part produced using any given processing conditions, in order to produce parts that are “born certified” and do not need to be tested post fabrication.

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 3D Puzzle in Cube Pattern for Anisotropic/Isotropic Mechanical Control of Structure Fabricated by Metal Additive Manufacturing

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 959
Author(s):  
Naoko Ikeo ◽  
Hidetsugu Fukuda ◽  
Aira Matsugaki ◽  
Toru Inoue ◽  
Ai Serizawa ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Functional Performance ◽  
Three Dimensional ◽  
Material Design ◽  
Metal Additive Manufacturing ◽  
Anisotropic Mechanical Properties ◽  
Innovative Material ◽  
Living Tissues ◽  
Metal Additive

Metal additive manufacturing is a powerful tool for providing the desired functional performance through a three-dimensional (3D) structural design. Among the material functions, anisotropic mechanical properties are indispensable for enabling the capabilities of structural materials for living tissues. For biomedical materials to replace bone function, it is necessary to provide an anisotropic mechanical property that mimics that of bones. For desired control of the mechanical performance of the materials, we propose a novel 3D puzzle structure with cube-shaped parts comprising 27 (3 × 3 × 3) unit compartments. We designed and fabricated a Co–Cr–Mo composite structure through spatial control of the positional arrangement of powder/solid parts using the laser powder bed fusion (L-PBF) method. The mechanical function of the fabricated structure can be predicted using the rule of mixtures based on the arrangement pattern of each part. The solid parts in the cubic structure were obtained by melting and solidifying the metal powder with a laser, while the powder parts were obtained through the remaining nonmelted powders inside the structure. This is the first report to achieve an innovative material design that can provide an anisotropic Young’s modulus by arranging the powder and solid parts using additive manufacturing technology.

Failures Related to Metal Additive Manufacturing

2021 ◽  
pp. 250-265
Author(s):  
Daniel P. Dennies ◽  
S. Lampman
Keyword(s):  
Quality Control ◽  
Additive Manufacturing ◽  
Powder Bed Fusion ◽  
Key Factors ◽  
Powder Bed ◽  
Metal Additive Manufacturing ◽  
Design Considerations ◽  
Directed Energy ◽  
Am Processes ◽  
Metal Additive

Abstract This article provides an overview of metal additive manufacturing (AM) processes and describes sources of failures in metal AM parts. It focuses on metal AM product failures and potential solutions related to design considerations, metallurgical characteristics, production considerations, and quality assurance. The emphasis is on the design and metallurgical aspects for the two main types of metal AM processes: powder-bed fusion (PBF) and directed-energy deposition (DED). The article also describes the processes involved in binder jet sintering, provides information on the design and fabrication sources of failure, addresses the key factors in production and quality control, and explains failure analysis of AM parts.

scholarly journals Local Thermal Rates and Gradients in Laser Powder Bed Fusion Metal Additive Manufacturing Method: Computer Simulation

2021 ◽  
Author(s):  
Hamed Hosseinzadeh
Keyword(s):  
Additive Manufacturing ◽  
Laser Power ◽  
Thermal Gradients ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Powder Bed ◽  
Metal Additive Manufacturing ◽  
Scan Speed ◽  
Simulation Results ◽  
Metal Additive

The powder bed fusion (PBF) metal additive manufacturing (AM) method uses an energy source like a laser to melt the metal powders. The laser can locally melt the metal powders and creates a solid structure as it moves. The complexity of the heat distribution in laser PBF metal AM is one of the main features that need to be accurately addressed and understood to design and manage an optimized printing process. In this research, the dependency of local thermal rates and gradients on print after solidification (in the heat-affected zone) was numerically simulated and studied to provide information for designing the print process. The simulation results were validated by independent experimental results. The simulation shows that the local thermal rates are higher at higher laser power and scan speed. Also, the local thermal gradients increase if the laser power increases. The effect of scan speed on the thermal gradients is opposite during heating versus cooling times. Increasing the scan speed increases the local thermal gradients in the cooling times and decreases the local thermal gradients during the heating. In addition, these simulation results could be used in artificial intelligence (AI) and machine learning for developing digital additive manufacturing.

scholarly journals Additive Manufacturing (AM) of Metallic Alloys

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 704
Author(s):  
Flaviana Calignano
Keyword(s):  
Additive Manufacturing ◽  
Metallic Alloys ◽  
Waste Material ◽  
Lead Times ◽  
Metal Additive Manufacturing ◽  
Lower Weight ◽  
Industrial Sectors ◽  
Potential Failure ◽  
Am Processes ◽  
Metal Additive

The introduction of metal additive manufacturing (AM) processes in industrial sectors, such as the aerospace, automotive, defense, jewelry, medical and tool-making fields, has led to a significant reduction in waste material and in the lead times of the components, innovative designs with higher strength, lower weight and fewer potential failure points from joining features [...]

scholarly journals Modelling of Microstructure Formation in Metal Additive Manufacturing: Recent Progress, Research Gaps and Perspectives

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1425
Author(s):  
Dayalan R. Gunasegaram ◽  
Ingo Steinbach
Keyword(s):  
Additive Manufacturing ◽  
Process Parameters ◽  
Computational Modelling ◽  
Vital Role ◽  
Formation Mechanisms ◽  
Microstructure Formation ◽  
Metal Additive Manufacturing ◽  
The Status ◽  
Am Processes ◽  
Metal Additive

Microstructures encountered in the various metal additive manufacturing (AM) processes are unique because these form under rapid solidification conditions not frequently experienced elsewhere. Some of these highly nonequilibrium microstructures are subject to self-tempering or even forced to undergo recrystallisation when extra energy is supplied in the form of heat as adjacent layers are deposited. Further complexity arises from the fact that the same microstructure may be attained via more than one route—since many permutations and combinations available in terms of AM process parameters give rise to multiple phase transformation pathways. There are additional difficulties in obtaining insights into the underlying phenomena. For instance, the unstable, rapid and dynamic nature of the powder-based AM processes and the microscopic scale of the melt pool behaviour make it difficult to gather crucial information through in-situ observations of the process. Therefore, it is unsurprising that many of the mechanisms responsible for the final microstructures—including defects—found in AM parts are yet to be fully understood. Fortunately, however, computational modelling provides a means for recreating these processes in the virtual domain for testing theories—thereby discovering and rationalising the potential influences of various process parameters on microstructure formation mechanisms. In what is expected to be fertile ground for research and development for some time to come, modelling and experimental efforts that go hand in glove are likely to provide the fastest route to uncovering the unique and complex physical phenomena that determine metal AM microstructures. In this short Editorial, we summarise the status quo and identify research opportunities for modelling microstructures in AM. The vital role that will be played by machine learning (ML) models is also discussed.

A Comparative Study of Metal Additive Manufacturing Processes for Elevated Sustainability

2019 ◽  
Author(s):  
Wenbo Min ◽  
Sheng Yang ◽  
Ying Zhang ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Additive Manufacturing ◽  
Environmental Performance ◽  
Production Efficiency ◽  
Batch Size ◽  
Design Solution ◽  
Metal Additive Manufacturing ◽  
Direct Energy ◽  
Environmental Performance Assessment ◽  
Am Processes ◽  
Metal Additive

Abstract Metal additive manufacturing (AM) processes have gone through a compound growth over the past decade, and the technology is widely applied in industries like aerospace, automobile and bio-medical fields. There is an increasing need to understand and improve its sustainability given the high profile of existing environmental challenges. This paper aims at developing a precise comparative model for the three major metal AM processes (including Laser Powder Bed Fusion (LPBF), Electron Beam Melting (EBM), and Direct Energy Deposition (DED)) with respect to environmental performance assessment with a future goal of providing closed-loop feedbacks for design optimization with elevated sustainability. To improve the precision of previously reported models, new factors including embodied impacts of machine and recycled powder, operation patterns, system lifespan and batch size, are considered. A topologically optimized rocket bracket made of Ti6Al4V is used as an example to investigate the environmental performance of the three processes. The results showed that given the same design solution, the EBM had the lowest environmental impacts for low batch size, while the DED excelled at production efficiency.

scholarly journals Review: The Impact of Metal Additive Manufacturing on the Aerospace Industry

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1286 ◽  
Author(s):  
Shahir Mohd Yusuf ◽  
Samuel Cutler ◽  
Nong Gao
Keyword(s):  
Additive Manufacturing ◽  
Outer Space ◽  
Aerospace Industry ◽  
Space Vehicles ◽  
Metal Additive Manufacturing ◽  
Wide Range ◽  
Metallic Parts ◽  
The Impact ◽  
Research Stage ◽  
Metal Additive

Metal additive manufacturing (AM) has matured from its infancy in the research stage to the fabrication of a wide range of commercial functional applications. In particular, at present, metal AM is now popular in the aerospace industry to build and repair various components for commercial and military aircraft, as well as outer space vehicles. Firstly, this review describes the categories of AM technologies that are commonly used to fabricate metallic parts. Then, the evolution of metal AM used in the aerospace industry from just prototyping to the manufacturing of propulsion systems and structural components is also highlighted. In addition, current outstanding issues that prevent metal AM from entering mass production in the aerospace industry are discussed, including the development of standards and qualifications, sustainability, and supply chain development.

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