Improving solid freeform fabrication by laser-based additive manufacturing

2002 ◽  
Vol 216 (9) ◽  
pp. 1253-1264 ◽  
Author(s):  
D Hu ◽  
H Mei ◽  
R Kovacevic
Keyword(s):  
Additive Manufacturing ◽  
Metal Powder ◽  
Laser Cladding ◽  
Closed Loop ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
Closed Loop Control ◽  
Loop Control ◽  
Freeform Fabrication ◽  
Laser Cladding Process

Solid freeform fabrication (SFF) methods for metal part building, such as three-dimensional laser cladding, are generally less stable and less repeatable than other rapid prototyping methods. A large number of parameters govern the three-dimensional laser cladding process. These parameters are sensitive to the environmental variations, and they also influence each other. This paper introduces the research work in Research Center for Advanced Manufacturing (RCAM) to improve the performance of its developed three-dimensional laser cladding process: laser-based additive manufacturing (LBAM). Metal powder delivery real-time sensing is studied to achieve a further controllable powder delivery that is the key technology to build a composite material or alloy with a functionally gradient distribution. An opto-electronic sensor is designed to sense the powder delivery rate in real time. The experimental results show that the sensor's output voltage has a good linear relationship with the powder delivery rate. A closed-loop control system is also built for heat input control in the LBAM process, based on infrared image sensing. A camera with a high frame rate (up to 800frame/s) is installed coaxially to the top of the laser—nozzle set-up. A full view of the infrared images of the molten pool can be acquired with a short nozzle—substrate distance in different scanning directions, eliminating the image noise from the metal powder. The closed-loop control results show a great improvement in the geometrical accuracy of the built feature.

Heat Input Control in 3D Laser Cladding Based on Infrared Sensing

2001 ◽  
Author(s):  
Dongming Hu ◽  
Yunxin Wu ◽  
Radovan Kovacevic
Keyword(s):  
Laser Cladding ◽  
Heat Input ◽  
Molten Pool ◽  
Closed Loop ◽  
Solid Freeform Fabrication ◽  
Infrared Image ◽  
Frame Rate ◽  
Closed Loop Control ◽  
Loop Control ◽  
Infrared Sensing

Abstract Solid Freeform Fabrication (SFF) methods for building metallic part, such as 3D laser cladding, are generally less stable and less repeatable than other rapid prototyping methods. The infrared image of the molten pool is a promising sensing technique for the closed-loop control of the cladding process. In this paper, the closed-loop control of heat input based on infrared image sensing in 3D laser cladding is introduced. A high frame-rate (up to 800frame/s) camera is installed coaxially at the top of the laser-nozzle setup. A full view of the infrared images of the molten pool can be acquired with a short nozzle-substrate distance in different scanning directions, eliminating the noise from the metal powder. The features of the images show a clear relationship with the variation of the cladding process parameters. The closed-loop control results show a great improvement in the geometrical accuracy and microstructure of the built part.

scholarly journals Localized electrodeposition micro additive manufacturing of pure copper microstructures

2021 ◽  
Author(s):  
Wanfei Ren ◽  
Jinkai Xu ◽  
Zhongxu Lian ◽  
Xiaoqing Sun ◽  
Zheming Xu ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Electrochemical Deposition ◽  
Closed Loop ◽  
Pure Copper ◽  
Closed Loop Control ◽  
Helical Spring ◽  
Loop Control ◽  
Helical Springs ◽  
Atomic Force ◽  
Microscopic Morphology

Abstract The fabrication of pure copper microstructures with submicron resolution has found a host of applications such as 5G communications and highly sensitive detection. The tiny and complex features of these structures can enhance device performance during high-frequency operation. However, the easy manufacturing of microstructures is still a challenge. In this paper, we present localized electrochemical deposition micro additive manufacturing (LECD-μAM), combining localized electrochemical deposition (LECD) and closed-loop control of atomic force servo technology, which can print helical springs and hollow tubes very effectively. We further demonstrate an overall model based on pulsed microfluidics from a hollow cantilever LECD process and the closed-loop control of an atomic force servo. The printing state of the micro-helical springs could be assessed by simultaneously detecting the Z-axis displacement and the deflection of the atomic force probe (AFP) cantilever. The results showed that it took 361 s to print a helical spring with a wire length of 320.11 μm at a deposition rate of 0.887 μm/s, which could be changed on the fly by simply tuning the extrusion pressure and the applied voltage. Moreover, the in situ nanoindenter was used to measure the compressive mechanical properties of the helical spring. The shear modulus of the helical spring material was about 60.8 GPa, much higher than that of bulk copper (~44.2 GPa). Additionally, the microscopic morphology and chemical composition of the spring were characterized. These results delineated a new way of fabricating terahertz transmitter components and micro-helical antennas with LECD-μAM technology.

Laser Cladding Forming and Closed-Loop Control of Thickness-Variable Eccentric Ring Structure

2018 ◽  
Vol 45 (3) ◽  
pp. 0302007
Author(s):  
沈婷 Shen Ting ◽  
石拓 Shi Tuo ◽  
傅戈雁 Fu Geyan ◽  
张锐 Zhang Rui ◽  
胡晔 Hu Ye
Keyword(s):  
Laser Cladding ◽  
Closed Loop ◽  
Ring Structure ◽  
Closed Loop Control ◽  
Loop Control ◽  
Eccentric Ring ◽  
Thickness Variable

Dynamical Identification Model of Laser Cladding Width in Metal Parts Laser Shaping Process

2013 ◽  
Vol 820 ◽  
pp. 216-219
Author(s):  
Shu Juan Jiang ◽  
Fei Fei Yu ◽  
Mao Zheng Fu
Keyword(s):  
Laser Cladding ◽  
Closed Loop ◽  
Scanning Speed ◽  
Step Response ◽  
Closed Loop Control ◽  
Loop Control ◽  
Simulating Experiment ◽  
Metal Parts ◽  
Shaping Process

The dynamical model of laser cladding width is identified by the method of step response experiments. Mathematical models between the cladding width and the laser power, the scanning speed, or the powder flowrate are established respectively according to corresponding experimental results. Simulating experiment results verify the validity of these models. The dynamical identification lays foundation for the closed loop control in laser shaping process so as to improve the quality of the laser formed parts.

Laser Cladding Based Solid Freeform Fabrication and Direct Metal Deposition

2006 ◽  
Author(s):  
Huan Qi ◽  
Jyotirmoy Mazumder
Keyword(s):  
Laser Beam ◽  
Laser Cladding ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
High Energy ◽  
Metal Deposition ◽  
Direct Metal Deposition ◽  
Effective Control ◽  
Metal Powders ◽  
Freeform Fabrication

Three-dimensional additive manufacturing or solid freeform fabrication (SFF) techniques, originated in the rapid fabrication of non-functional physical prototypes in polymers (Rapid Prototyping), have matured to the manufacture of functional prototypes, short-run production products, and now even advanced engineering designs. Laser-based material deposition or laser cladding has been used as a SFF technique, in which a laser beam is used as a precise high-energy thermal source to melt preplaced or pneumatically delivered metal powders and make solidified deposits on a substrate. By using laser cladding techniques, three-dimensional fully dense components can be built line-by-line and layer-by-layer directly from a CAD model with tailored material properties. Laser cladding is essentially a fusion and solidification (thermal) process, which involves complicated interactions between the laser beam, metal powders, the base material (substrate), and processing gases. Maintaining a stable and uniform melt pool during laser cladding is critical to produce dimensional accuracy and material integrity. An effective control of energy (laser power) spatial and temporal distributions in either an open-loop or closed-loop laser cladding process is essential to achieve the high quality results. This paper reviews, from a laser-material interaction point of view, various laser cladding based SFF processes, and particularly the direct metal deposition technique.

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