scholarly journals Correlations between Process and Geometric Parameters in Additive Manufacturing of Austenitic Stainless Steel Components Using 3DPMD

2021 ◽  
Vol 11 (12) ◽  
pp. 5610
Author(s):  
Kevin Hoefer
Keyword(s):  
Additive Manufacturing ◽  
Layer Thickness ◽  
Mass Flow ◽  
Cross Sections ◽  
System Analysis ◽  
Control Variable ◽  
Welding Current ◽  
Scientific Work ◽  
Deposition Process ◽  
Powder Mass

The additive manufacturing of components is characterized by a layered build-up. The stability of the build-up process with regard to the component geometry and the layer thickness is essential for the success of the entire system. A prerequisite for this is the exact knowledge of the interrelationships between the process, construction parameters and the resulting component geometry, respectively. These correlations are determined within the study using the 3D Plasma Metal Deposition Process (3DPMD). For this purpose, the process is first subjected to a system analysis. Possible influencing variables were identified with regard to the question “Which system parameters influence the component geometry?” and then prioritized. Then, the influence of control factors (welding current intensity, welding speed, and powder mass flow) was investigated according to the specifications of the Design of Experiments (DOE) method by means of a full-factorial experimental design and evaluated on the basis of metallographic cross-sections. As a result, it was determined that the system parameter powder mass flow only influences the layer thickness and not the wall thickness and is, therefore, available as a process control variable. In sum, comprehensive knowledge of complex relationships between the control parameters and the component geometry in additive manufacturing using 3DPMD was achieved and forms the basis for further scientific work.

scholarly journals In situ measurement and closed-loop control for powder supply processes

2021 ◽  
Author(s):  
Philipp Peter Breese ◽  
Tobias Hauser ◽  
Daniel Regulin ◽  
Stefan Seebauer ◽  
Christian Rupprecht
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Closed Loop ◽  
In Situ Measurement ◽  
Closed Loop Control ◽  
Loop Control ◽  
Powder Feeder ◽  
Powder Mass

AbstractThe powder mass flow rate is one of the main parameters regarding the geometrical precision of built components in the additive manufacturing process of laser metal deposition. However, its accuracy, constancy, and repeatability over the course of the running process is not given. Reasons among others are the performance of the powder conveyors, the complex nature of the powder behavior, and the resulting issues with existing closed-loop control approaches. Additionally, a direct in situ measurement of the powder mass flow rate is only possible with intrusive methods. This publication introduces a novel approach to measure the current powder mass flow rate at a frequency of 125 Hz. The volumetric powder flow evaluation given by a simple optical sensor concept was transferred to a mass flow rate through mathematical dependencies. They were found experimentally for a nickel-based powder (Inconel 625) and are valid for a wide range of mass flow rates. With this, the dynamic behavior of a vibration powder feeder was investigated and a memory effect dependent on previous powder feeder speeds was discovered. Next, a closed-loop control with the received sensor signal was implemented. The concept as a whole gives a repeatable and accurate powder mass flow rate while being universally retrofittable and applicable. In a final step, the improved dynamic and steady performance of the powder mass flow rate with closed-loop control was validated. It showed a reduction of mean relative errors for step responses of up to 81% compared to the uncontrolled cases.

scholarly journals Low-Roughness-Surface Additive Manufacturing of Metal-Wire Feeding with Small Power

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4265
Author(s):  
Bobo Li ◽  
Bowen Wang ◽  
Greg Zhu ◽  
Lijuan Zhang ◽  
Bingheng Lu
Keyword(s):  
Additive Manufacturing ◽  
High Surface ◽  
Deposition Process ◽  
High Energy ◽  
Width Ratio ◽  
Thin Wall ◽  
Small Power ◽  
High Surface Quality ◽  
Wall Structures ◽  
Wire Feed

Aiming at handling the contradiction between power constraint of on-orbit manufacturing and the high energy input requirement of metal additive manufacturing (AM), this paper presents an AM process based on small-power metal fine wire feed, which produces thin-wall structures of height-to-width ratio up to 40 with core-forming power only about 50 W. In this process, thermal resistance was introduced to optimize the gradient parameters which greatly reduces the step effect of the typical AM process, succeeded in the surface roughness (Ra) less than 5 μm, comparable with that obtained by selective laser melting (SLM). After a 10 min electrolyte-plasma process, the roughness of the fabricated specimen was further reduced to 0.4 μm, without defects such as pores and cracks observed. The ultimate tensile strength of the specimens measured about 500 MPa, the relative density was 99.37, and the Vickers hardness was homogeneous. The results show that the proposed laser-Joule wire feed-direct metal deposition process (LJWF-DMD) is a very attractive solution for metal AM of high surface quality parts, particularly suitable for rapid prototyping for on-orbit AM in space.

scholarly journals Development of an Additive Manufacturing System for the Deposition of Thermoplastics Impregnated with Carbon Fibers

2019 ◽  
Vol 3 (2) ◽  
pp. 35 ◽  
Author(s):  
Miguel Reis Silva ◽  
António M. Pereira ◽  
Nuno Alves ◽  
Gonçalo Mateus ◽  
Artur Mateus ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Carbon Fibers ◽  
Low Cost ◽  
Deposition Process ◽  
Processing Parameters ◽  
Yarn Diameter ◽  
Thermoplastic Matrix ◽  
Anisotropic Mechanical Properties ◽  
Long Carbon Fiber

This work presents an innovative system that allows the oriented deposition of continuous fibers or long fibers, pre-impregnated or not, in a thermoplastic matrix. This system is used in an integrated way with the filamentary fusion additive manufacturing technology and allows a localized and oriented reinforcement of polymer components for advanced engineering applications at a low cost. To demonstrate the capabilities of the developed system, composite components of thermoplastic matrix (polyamide) reinforced with pre-impregnated long carbon fiber (carbon + polyamide), 1 K and 3 K, were processed and their tensile and flexural strength evaluated. It was demonstrated that the tensile strength value depends on the density of carbon fibers present in the composite, and that with the passage of 2 to 4 layers of fibers, an increase in breaking strength was obtained of about 366% and 325% for the 3 K and 1 K yarns, respectively. The increase of the fiber yarn diameter leads to higher values of tensile strength of the composite. The obtained standard deviation reveals that the deposition process gives rise to components with anisotropic mechanical properties and the need to optimize the processing parameters, especially those that lead to an increase in adhesion between deposited layers.

scholarly journals Spreadability Testing of Powder for Additive Manufacturing

2021 ◽  
Vol 166 (1) ◽  
pp. 9-13
Author(s):  
Christopher Neil Hulme-Smith ◽  
Vignesh Hari ◽  
Pelle Mellin
Keyword(s):  
Additive Manufacturing ◽  
Layer Thickness ◽  
Measurement Procedure ◽  
Quantitative Information ◽  
Thin Layers ◽  
Spreading Speed ◽  
Powder Bed ◽  
Critical Step ◽  
Robust Image

AbstractThe spreading of powders into thin layers is a critical step in powder bed additive manufacturing, but there is no accepted technique to test it. There is not even a metric that can be used to describe spreading behaviour. A robust, image-based measurement procedure has been developed and can be implemented at modest cost and with minimal training. The analysis is automated to derive quantitative information about the characteristics of the spread layer. The technique has been demonstrated for three powders to quantify their spreading behaviour as a function of layer thickness and spreading speed.

scholarly journals Analysis of the Process Parameter Influence in Laser Cladding of 316L Stainless Steel

2018 ◽  
Vol 2 (3) ◽  
pp. 55 ◽  
Author(s):  
Piera Alvarez ◽  
M. Montealegre ◽  
Jose Pulido-Jiménez ◽  
Jon Arrizubieta
Keyword(s):  
Stainless Steel ◽  
Laser Cladding ◽  
Process Parameters ◽  
Cross Sections ◽  
316L Stainless Steel ◽  
Deposition Process ◽  
Process Parameter ◽  
Optimum Process ◽  
Processing Times ◽  
Manufacturing Technologies

Laser Cladding is one of the leading processes within Additive Manufacturing technologies, which has concentrated a considerable amount of effort on its development. In regard to the latter, the current study aims to summarize the influence of the most relevant process parameters in the laser cladding processing of single and compound volumes (solid forms) made from AISI 316L stainless steel powders and using a coaxial nozzle for their deposition. Process speed, applied laser power and powder flow are considered to be the main variables affecting the laser cladding in single clads, whereas overlap percentage and overlapping strategy also become relevant when dealing with multiple clads. By setting appropriate values for each process parameter, the main goal of this paper is to develop a processing window in which a good metallurgical bond between the delivered powder and the substrate is obtained, trying simultaneously to maintain processing times at their lowest value possible. Conventional metallography techniques were performed on the cross sections of the laser tracks to measure the effective dimensions of clads, height and width, as well as the resulting dilution value. Besides the influence of the overlap between contiguous clads and layers, physical defects such as porosity and cracks were also evaluated. Optimum process parameters to maximize productivity were defined as 13 mm/s, 2500 W, 30% of overlap and a 25 g/min powder feed rate.

scholarly journals Effects of robotic CO2 arc welding variables on penetration and microstructure of weld in C-80 grade steel

2010 ◽  
Vol 7 (1) ◽  
pp. 67-75
Author(s):  
Hamid Reza Ghazvinloo ◽  
Abbas Honarbakhsh-Raouf ◽  
Nasim Shadfar
Keyword(s):  
Weld Metal ◽  
Cross Sections ◽  
Arc Welding ◽  
Welding Process ◽  
Welding Current ◽  
Residual Austenite ◽  
Martensite Phase ◽  
Optical Observations ◽  
Bead Geometry ◽  
Steel Joints

Generally, the quality and properties of a weld joint is strongly influenced by welding variables during process. In order to achieve an ideal weld, it is important attention to bead geometry and microstructure evolution of weld metal. The effect of process variables on penetration and microstructure of C-80 steel joints produced by robotic CO2 arc welding was studied in present work. Different samples were produced by employing arc voltages of 23, 25 and 27 V, welding currents of 100, 110 and 120 A and welding speeds of 42, 62 and 82 cm/min. After welding process, geometric measurements were performed on welding specimens and the microstructural evolutions were investigated by optical observations of the weld cross sections. Results were clearly illustrated that increasing in welding current or arc voltage increases the depth of weld penetration. The highest penetration in this research was observed in 62 cm/min welding speed. The metallographic examinations also indicated that the microstructure of weld metal in all of specimens was composed mainly of martensite (M) and residual austenite (A) phases that a portion of martensite phase had been tempered.

Research on Powder Stream of Coaxial Powder Feeding in Laser Manufacturing Technology

2013 ◽  
Vol 423-426 ◽  
pp. 807-810
Author(s):  
Heng Quan ◽  
Yun Shan Wang ◽  
Li Feng Liu ◽  
Shao Jun Liu ◽  
Qing Ruo Meng
Keyword(s):  
Physical Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Concentration Field ◽  
Ccd Camera ◽  
Factors Affecting ◽  
Coaxial Nozzle ◽  
Powder Mass ◽  
Powder Feeding

Mathematical-physical model of powder stream in coaxial powder feeding was established. The concentration fields of powder stream of coaxial nozzle of different size and powder mass flow rate were analyzed. The concentration field and morphology of the powder stream were detected by CCD camera. The results show that the size of coaxial nozzle and powder mass flow rate are major factors affecting the powder stream. The mathematical-physical model and experimental data provide theoretical basis for laser cladding manufacturing.

Multiaxis wire and arc additive manufacturing for overhangs based on conical substrates

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fusheng Dai ◽  
Shuaifeng Zhang ◽  
Runsheng Li ◽  
Haiou Zhang
Keyword(s):  
Principal Component Analysis ◽  
Additive Manufacturing ◽  
Design Methodology ◽  
Principal Component ◽  
Deposition Process ◽  
Content Type ◽  
Melt Pool ◽  
Planning Approach ◽  
Intelligent Approach ◽  
Supporting Structures

Purpose This paper aims to present a series of approaches for three-related issues in multiaxis in wire and arc additive manufacturing (WAAM) as follows: how to achieve a stable and robust deposition process and maintain uniform growth of the part; how to maintain consistent formation of a melt pool on the surface of the workpiece; and how to fabricate an overhanging structure without supports. Design/methodology/approach The principal component analysis-based path planning approach is proposed to compute the best scanning directions of slicing contours for the generation of filling paths, including zigzag paths and parallel skeleton paths. These printing paths have been experimented with in WAAM. To maintain consistent formation of a melt pool at overhanging regions, the authors introduce definitions for the overhanging point, overhanging distance and overhanging vector, with which the authors can compute and optimize the multiaxis motion. A novel fabricating strategy of depositing the overhanging segments as a support for the deposition of filling paths is presented. Findings The second principal component of a planar contour is a reasonable scanning direction to generate zigzag filling paths and parallel skeleton filling paths. The overhanging regions of a printing layer can be supported by pre-deposition of overhanging segments. Large overhangs can be successfully fabricated by the multiaxis WAAM process without supporting structures. Originality/value An intelligent approach of generating zigzag printing paths and parallel skeleton printing paths. Optimizations of depositing zigzag paths and parallel skeleton paths. Applications of overhanging point overhanging distance and overhanging vector for multiaxis motion planning. A novel fabricating strategy of depositing the overhanging segments as a support for the deposition of filling paths.

High Efficiency Molding by Real-Time Control of Distance Between Nozzle and Melt Pool in Directed Energy Deposition Process

2020 ◽  
Author(s):  
Kengo Aizawa ◽  
Masahiro Ueda ◽  
Teppei Shimada ◽  
Hideki Aoyama ◽  
Kazuo Yamazaki
Keyword(s):  
Additive Manufacturing ◽  
Real Time ◽  
Material Properties ◽  
High Efficiency ◽  
Dimensional Accuracy ◽  
Deposition Process ◽  
Deposition Efficiency ◽  
Experimental Results ◽  
Real Time Control ◽  
Molding Process

Abstract Laser metal deposition (LMD) is an additive manufacturing technique, whose performance can be influenced by a considerable number of factors and parameters. Typically, a powder is carried by an inert gas and sprayed by a nozzle, with a coaxial laser beam passing through the nozzle and overlapping the powder flow, thereby generating a molten material pool on a substrate. Monitoring the evolution of this process allows for a better comprehension and control of the process, thereby enhancing the deposition quality. As the metal additive manufacturing mechanism has not yet been elucidated, it is not clear how process parameters affect material properties, molding accuracy, and molding efficiency. When cladding is performed under uncertain conditions, a molded part with poor material properties and dimensional accuracy is created. In this paper, we propose a method for high efficiency molding by controlling the distance between the head nozzle and the molten pool in real time. The distance is identified by an originally developed sensor based on a triangulation method. According to the distance, the head nozzle is automatically controlled into the optimum position. As a result, an ideal molding process can be generated, so that high efficiency molding and high-quality material properties can be obtained. Experimental results show that continuing deposition at the optimum distance assists in achieving deposition efficiency and dimensional accuracy. According to the specific experimental results of this method, the modeling efficiency was increased by 27% compared to the method without correction, and the modeling was successful with an error within 1 mm.

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