Laser direct metal deposition process of thin-walled parts using variable spot by inside-beam powder feeding

2018 ◽  
Vol 24 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Lifang Wang ◽  
Gangxian Zhu ◽  
Tuo Shi ◽  
Jizhuo Wu ◽  
Bin Lu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Laser Spot ◽  
Layer By Layer ◽  
Single Track ◽  
Content Type ◽  
Practical Applications ◽  
Thin Walled ◽  
Powder Feeding

Purpose The purpose of this paper is to improve the forming efficiency and quality of unequal-width parts fabricated by laser direct metal deposition technology, some experiments were designed. Design/methodology/approach A new method by varying laser spot was adopted to fabricate unequal-width single track using one scanning rather than multi-track overlapping in the way of the inside-beam powder feeding, and the thin-walled parts were fabricated layer by layer. The theoretical model among layer thickness of z-axis, height of single track and the section curve order of single track was established. Findings The top surface unevenness of the thin-walled parts could be compensated automatically within the laser defocusing ranges from −2.5 to −5 mm and from 0.5 to 2.5 mm. The growth rate with the large width/height ratio was more than the small ratio, while the set height of the single track was uniform. The problem of non-uniform growth rate could be solved based on a stepped single-track method. The thin-walled parts with the smooth top surface was fabricated layer by layer which had a continuously variable width from 1 to 3 mm by splicing the laser defocusing range. Practical implications The shapes of the to-be-fabricated parts affect variable laser spot process in practical applications. For example, it will be difficult to apply variable laser spot process on the parts with the hole features. Originality/value This paper provided a guidance for forming unequal-width parts by laser direct metal deposition based on the inside-beam powder feeding.

Parameter Nondimensionalization in Laser Direct Metal Deposition Formation of Inconel 625 and Its Influence on Single Track Geometric Morphology

2017 ◽  
Vol 44 (3) ◽  
pp. 0302010 ◽  
Author(s):  
李进宝 Li Jinbao ◽  
商 硕 Shang Shuo ◽  
孙有政 Sun Youzheng ◽  
郭快快 Guo Kuaikuai ◽  
刘常升 Liu Changsheng
Keyword(s):  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Inconel 625 ◽  
Single Track ◽  
Geometric Morphology

Advances in Direct Metal Deposition

2013 ◽  
Author(s):  
Jyoti Mazumder ◽  
Lijun Song
Keyword(s):  
Additive Manufacturing ◽  
Optical Sensors ◽  
Thermal Cycle ◽  
Industrial Revolution ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Layer By Layer ◽  
Enabling Technology ◽  
Economic Space ◽  
Line Process

Recently Additive Manufacturing (AM) has been hailed as the “third industrial revolution” by The Economist magazine [April-2012]. Precision of the product manufactured by AM largely depends on the on line process diagnostics and control. AM caters to the quest for a material to suit the service performance, which is almost as old as the human civilization. An enabling technology which can build, repair or reconfigure components layer by layer or even pixel by pixel with appropriate materials to match the performance will enhance the productivity and thus reduce energy consumption. With the globalization, “Economic Space” for an organization is now spreads all across the globe. The promise of AM for Global Platform for precision additive manufacturing largely depends on the speed and accuracy of in-situ optical diagnostics and its capability to integrate with the process control. The two main groups of AM are powder bed (e.g. Laser Sintering) and pneumatically delivered powder (e.g. Direct Metal Deposition [DMD]) to fabricate components. DMD has closed loop capability, which enables better dimension and thermal cycle control. This enables one to deposit different material at different pixels with a given height directly from a CAD drawing. The feed back loop also controls the thermal cycle. New optical Sensors are either developed or being developed to control geometry using imaging, cooling rate by monitoring temperature, microstructure, temperature and composition using optical spectra. Ultimately these sensors will enable one to “Certify as you Build”. Flexibility of the process is enormous and essentially it is an enabling technology to materialize many a design. Several cases will be discussed to demonstrate the additional capabilities possible with the new sensors. Conceptually one can seat in Singapore and fabricate in Shanghai. Such systems will be a natural choice for a Global “Economic Space”.

An analytical model of the melt pool and single track in coaxial laser direct metal deposition (LDMD) additive manufacturing

2017 ◽  
Vol 02 (04) ◽  
pp. 1750013 ◽  
Author(s):  
Jian Liu ◽  
Erica Stevens ◽  
Qingchen Yang ◽  
Markus Chmielus ◽  
Albert C. To
Keyword(s):  
Analytical Model ◽  
Interaction Model ◽  
Source Model ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Single Track ◽  
Gaussian Laser Beam ◽  
Track Geometry ◽  
Geometry Model ◽  
Melt Pool

An analytical model was developed for the melt pool and single scan track geometry as a function of process parameters. For computational efficiency, the developed model has simple mathematical forms with essential physics taken into account, without the need for complicated numerical simulation. In this research, a non-diverging Gaussian laser beam and coaxial diverging Gaussian powder stream combination is used to represent the coaxial laser direct metal deposition (LDMD) process. Analytical laser-powder interaction model is used to obtain the distribution of attenuated laser intensity and temperature of heated powders at the substrate. On the substrate, the melt pool is calculated by integrating Rosenthal's point heat source model. An iterative procedure is used to ensure the mass–energy balances and to calculate the melt pool and catchment efficiency. By assuming that the assimilated powder will reshape due to surface tension before solidification, a simple clad geometry model is established. The proposed model is used to simulate the geometry of single track depositions of Ti6Al4V, which shows a good agreement between model prediction and experimental results. This work demonstrates that the developed model has the potential to be used to narrow the parameter space for process optimization.

Tensile strength of functionally graded and wafer layered structures produced by direct metal deposition

2014 ◽  
Vol 20 (5) ◽  
pp. 360-368 ◽  
Author(s):  
Mehdi Soodi ◽  
Syed H. Masood ◽  
Milan Brandt
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Tensile Tests ◽  
Layered Structures ◽  
Metal Deposition ◽  
Functionally Graded ◽  
Direct Metal Deposition ◽  
Engineering Applications ◽  
Diverse Range ◽  
Content Type

Purpose – This paper aims to investigate the changes in tensile properties of novel functionally graded materials (FGMs) and wafer structures created by direct metal deposition (DMD) additive manufacturing (AM) technology. Design/methodology/approach – Laser-assisted DMD was used to create two innovative sets of metallic structures – the functionally graded and wafer-layered structures – using pairs of six different engineering alloys in different combinations. These alloys were selected due to their high popularity within a diverse range of industries and engineering applications. The laser-assisted DMD was selected as a suitable technique to create these complex structures because of its capability to deposit more than one alloy powder at a time. After creation of these structures, their tensile strength was tested in a series of tensile tests and the results were compared with those of single alloy samples. Findings – It was observed that the mechanical properties of FGMs and wafer structure samples were clearly different from those of the single alloy samples, a fact which creates a whole pool of opportunities for development of new materials or structures with desired mechanical properties that cannot be achieved in single alloy parts. Originality/value – The study demonstrates the application of the DMD process to produce unique structures and materials, which would be high in demand in engineering applications, where metallic parts are exposed to high loads and where excessive tensile stresses may adversely affect the performance of such parts.

Mechanical performance of plymetal structures subjected to impact loading

2017 ◽  
Vol 9 (1) ◽  
pp. 65-76
Author(s):  
SH Masood ◽  
D Ruan ◽  
P Rajapatruni
Keyword(s):  
Stainless Steel ◽  
Mechanical Performance ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Layer By Layer ◽  
Metal Powders ◽  
Metallic Structure ◽  
Stainless Steel 316L ◽  
Ballistic Performance ◽  
Ballistic Resistance

Plymetal is a new type of composite metallic structure based on the concept of plywood created by laser direct metal deposition additive manufacturing technology. Two different metal powders, 316L stainless steel and H13 tool steel, are deposited in alternative parallel rows in each layer in the defined orientations to create a plymetal structure. In this research, the plymetal was manufactured by the POM DMD 505 machine, in which a laser beam melts various metal powders deposited through a coaxial nozzle in a layer-by-layer manner to form a metallic structure. The ballistic performance of plymetal structures was then experimentally studied for high impact applications. Ballistic tests were carried out using a high-pressure gas gun. The plymetal plates of 3-mm-thick were subjected to impact of projectiles at various velocities and the results were compared with test results of stainless steel plates of different thicknesses. Results show that the ballistic resistance of the direct metal deposition generated plymetal structure is better than the ballistic resistance of the stainless steel 316L with the same thickness. Vickers hardness and face deformation characteristics of the plymetal samples and stainless steel samples were also investigated.

Design of Injection Nozzle in Direct Metal Deposition (DMD) Manufacturing of Thin-Walled Structures Based on 3D Models

2016 ◽  
Author(s):  
Jingyuan Yan ◽  
Ilenia Battiato ◽  
Georges Fadel
Keyword(s):  
Laser Energy ◽  
3D Models ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Injection Nozzle ◽  
Thin Walled Structures ◽  
Nozzle Shape ◽  
Thin Walled ◽  
Manufacturing Techniques ◽  
Optimization Methodology

The Direct Metal Deposition (DMD) process is one of the most important metal based additive manufacturing techniques available today. In this study, a print head design optimization methodology is proposed based on the finite element modeling of powder distribution and substrate temperature distribution. The design methodology is applied to the deposition of Ti-6Al-4V powder in building thin-walled (≈ 0.7 mm) structures, which is also applicable to solid parts. The design objective is to find the optimal design of the injection nozzle shape that can maximize the powder usage and minimize laser energy needs, later defined as powder and laser energy efficiencies. A neural network is built to investigate the nozzle shape parameters based on the results from the 3D powder flow model. With the methodology proposed in this study, the optimal injection nozzle design can be found.

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