Development of a Multi-Directional Metal 3D Printing System Based on Direct Metal Deposition

2019 ◽  
Author(s):  
Shiming Gao ◽  
Wei-Hsin Liao ◽  
Ping Guo
Keyword(s):  
Dimensional Accuracy ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Heat Accumulation ◽  
Laser Head ◽  
Laser Focus ◽  
Metal 3D Printing ◽  
Deposition Direction ◽  
Compact Design

Abstract Process parameters, including deposition direction, are crucial in direct metal deposition (DMD) for microstructure formation and mechanical properties of the final part. Multi-directional deposition along with in-situ deposition control can minimize deposition anisotropy and improve dimensional accuracy. In this paper, a DMD system is developed to achieve multi-directional metal deposition by using 6 degree-of-freedom (DOF) motion of the workpiece platform rather the laser head for a highly compact design. An in-situ control strategy with two independent loops of laser focus and power is developed to control the printing process based on the feedback from real-time melt pool geometry and intensity. Experimental results have shown that the laser focus and power control can significantly improve geometrical accuracy and reduce heat accumulation. In addition, system kinematics are derived and verified for the 6-DOF hexapod to achieve multi-directional deposition. Oblique structures have been successfully printed to demonstrate the effect of optimized build direction.

Thermal Analysis and Verification for Direct Metal Deposition of 0Cr18Ni9 Stainless Steel

2019 ◽  
Author(s):  
Jin Wang ◽  
Jing Shi ◽  
Yi Wang ◽  
Yun Bai
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Temperature Distribution ◽  
Process Parameters ◽  
Thermal Stresses ◽  
Infrared Camera ◽  
Dimensional Accuracy ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Heating And Cooling

Abstract Due to rapid cyclic heating and cooling in metal additive manufacturing processes, such as selective laser melting (SLM) and direct metal deposition (DMD), large thermal stresses will form and this may lead to the loss of dimensional accuracy or even cracks. The integration of numerical analysis and experimental validation provides a powerful tool that allows the prediction of defects, and optimization of the component design and the additive manufacturing process parameters. In this work, a numerical simulation on the thermal process of DMD of 0Cr18Ni9 stainless steel is conducted. The simulation is based on the finite volume method (FVM). An in-house code is developed, and it is able to calculate the temperature distribution dynamically. The model size is 30mm × 30mm × 10.5mm, containing 432,000 cells. A DMD experiment on the material with the same configuration and process parameters is also carried out, during which an infrared camera is adopted to obtain the surface temperature distribution continuously, and thermocouples are embedded in the baseplate to record the temperature histories. It is found that the numerical results agree with the experimental results well.

SEM of non-coated hepatocellular cytoskeleton of perfused livers

1984 ◽  
Vol 42 ◽  
pp. 306-307
Author(s):  
S.W. French ◽  
N.C. Benson ◽  
C. Davis-Scibienski
Keyword(s):  
Ambient Temperature ◽  
Critical Point ◽  
Protease Inhibitors ◽  
Metal Deposition ◽  
Heat Damage ◽  
Detergent Extraction ◽  
Cytoskeletal Elements ◽  
Triton X ◽  
Excised Tissue

Previous SEM studies of liver cytoskeletal elements have encountered technical difficulties such as variable metal coating and heat damage which occurs during metal deposition. The majority of studies involving evaluation of the cell cytoskeleton have been limited to cells which could be isolated, maintained in culture as a monolayer and thus easily extracted. Detergent extraction of excised tissue by immersion has often been unsatisfactory beyond the depth of several cells. These disadvantages have been avoided in the present study. Whole C3H mouse livers were perfused in situ with 0.5% Triton X-100 in a modified Jahn's buffer including protease inhibitors. Perfusion was continued for 1 to 2 hours at ambient temperature. The liver was then perfused with a 2% buffered gluteraldehyde solution. Liver samples including spontaneous tumors were then maintained in buffered gluteraldehyde for 2 hours. Samples were processed for SEM and TEM using the modified thicarbohydrazide procedure of Malich and Wilson, cryofractured, and critical point dried (CPD). Some samples were mechanically fractured after CPD.

Significance of continuous wave and pulsed wave laser in direct metal deposition

2021 ◽  
Author(s):  
S. Pratheesh Kumar ◽  
S. Elangovan ◽  
R. Mohanraj ◽  
V. Sathya Narayanan
Keyword(s):  
Continuous Wave ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Wave Laser

scholarly journals Direct Metal Deposition (DMD) for Tooling Repair of DIN 1.2343 Steel

Procedia CIRP ◽  
2020 ◽  
Vol 95 ◽  
pp. 23-28
Author(s):  
Mohammad Rabiey ◽  
Pascal Schiesser ◽  
Pascal Maerchy
Keyword(s):  
Metal Deposition ◽  
Direct Metal Deposition
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