Effect of depositing torch angle on the first layer of wire arc additive manufacture using cold metal transfer (CMT)

2019 ◽  
Vol 46 (2) ◽  
pp. 259-266 ◽  
Author(s):  
Chuanchu Su ◽  
Xizhang Chen
Keyword(s):  
Weld Pool ◽  
High Speed ◽  
Additive Manufacture ◽  
High Speed Camera ◽  
Porosity Formation ◽  
Cold Metal Transfer ◽  
Content Type ◽  
Deposition Direction ◽  
Cold Metal ◽  
Torch Angle

Purpose This paper aims to mainly report the impact of torch angle on the dynamic behavior of the weld pool which is recorded and monitored in real time with the aid of a high-speed camera system. The influence of depositing torch angle on the fluctuation behavior of weld pool and the quality of weld formation are compared and analyzed. Design/methodology/approach The FANUC controlled robotic manufacturing system comprised a Fronius cold metal transfer (CMT) Advanced 4000R power source, FANUC robot, water cooling system, wire feeding system and a gas shielding system. An infrared laser was used to illuminate the weld pool for high-speed imaging at 1,000 frames per second with CR600X2 high-speed camera. The high-speed camera was set up a 35 ° angle with the deposition direction to investigate the weld pool flow patterns derived from high-speed video and the effect of torch angles on the first layer of wire additive manufacture-CMT. Findings The experimental results demonstrated that different torch angles significantly influence on the deposited morphology, porosity formation rate and weld pool flow. Originality/value With regard to the first layer of wire arc additive manufacture of aluminum alloys, the change of torch angle is critical. It is clear that different torch angles significantly influence on the weld morphology, porosity formation and weld pool flow. Furthermore, under different torch angles, the deposited beads will produce different defects. To get well deposited beads, 0-10° torch could be made away from the vertical position of the deposition direction, in which the formation of deposited beads were well and less porosity and other defects.

Measuring the effects of a laser beam on melt pool fluctuation in arc additive manufacturing

2019 ◽  
Vol 25 (3) ◽  
pp. 488-495
Author(s):  
Jonas Näsström ◽  
Frank Brückner ◽  
Alexander F.H. Kaplan
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
High Speed ◽  
Surface Profile ◽  
High Speed Imaging ◽  
Cold Metal Transfer ◽  
Content Type ◽  
Pool Surface ◽  
Melt Pool ◽  
Cold Metal

Purpose The steadily growing popularity of additive manufacturing (AM) increases the demand for understanding fundamental behaviors of these processes. High-speed imaging (HSI) can be a useful tool to observe these behaviors, but many studies only present qualitative analysis. The purpose of this paper is to propose an algorithm-assisted method as an intermediate to rapidly quantify data from HSI. Here, the method is used to study melt pool surface profile movement in a cold metal transfer-based (CMT-based) AM process, and how it changes when the process is augmented with a laser beam. Design/methodology/approach Single-track wide walls are generated in multiple layers using only CMT, CMT with leading and with trailing laser beam while observing the processes using HSI. The studied features are manually traced in multiple HSI frames. Algorithms are then used for sorting measurement points and generating feature curves for easier comparison. Findings Using this method, it is found that the fluctuation of the melt surface in the chosen CMT AM process can be reduced by more than 35 per cent with the addition of a laser beam trailing behind the arc. This indicates that arc and laser can be a viable combination for AM. Originality/value The suggested quantification method was used successfully for the laser-arc hybrid process and can also be applied for studies of many other AM processes where HSI is implemented. This can help fortify and expand the understanding of many phenomena in AM that were previously too difficult to measure.

Effect of the CMT advanced process combined with an active cooling technique on macro and microstructural aspects of aluminum WAAM

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Felipe Ribeiro Teixeira ◽  
Fernando Matos Scotti ◽  
Ruham Pablo Reis ◽  
Américo Scotti
Keyword(s):  
Electrical Signal ◽  
Management Technique ◽  
Marginal Effect ◽  
Thin Wall ◽  
Cold Metal Transfer ◽  
Content Type ◽  
Active Cooling ◽  
Cold Metal ◽  
Wire Arc Additive Manufacturing ◽  
Cooling Technique

Purpose This paper aims to assess the combined effect of the Cold Metal Transfer (CMT) advanced process and of a thermal management technique (near immersion active cooling [NIAC]) on the macro and microstructure of Al wall-like preforms built by wire arc additive manufacturing (WAAM). As specific objective, it sought to provide information on the effects of the electrode-positive/electrode-negative (EP/EN) parameter in the CMT advanced process fundamental characteristics. Design/methodology/approach Initially, bead-on-plate deposits were produced with different EP/EN ratios, still keeping the same deposition rate, and the outcomes on the electrical signal traces and bead formation were analyzed. In a second stage, the EP/EN parameter and the layer edge to water distance (LEWD) parameter from the NIAC technique were systematically varied and the resultant macro and microstructures compared with those formed by applying natural cooling. Findings Constraints of EP/EN setting range were uncovered and discussed. The use of the NIAC technique favors the formation of finer grains. For a given EP/EN value, a variation in the NIAC intensity (LEWD value) showed marginal effect on grain size. When the EP/EN parameter effect is isolated, i.e. for a given LEWD setting, it was observed that an increase in the EP/EN level favors coarser grains. Originality/value Both the EP/EN parameter and the use of an active cooling technique (NIAC) might be used, even in combination, as effective tools for achieving proper macro and microstructure in WAAM of thin wall builds.

Cold Metal Transfer (CMT) Based Wire and Arc Additive Manufacture (WAAM) System

2018 ◽  
Vol 12 (6) ◽  
pp. 1278-1284 ◽  
Author(s):  
Xizhang Chen ◽  
Chuanchu Su ◽  
Yangfan Wang ◽  
Arshad Noor Siddiquee ◽  
Konovalov Sergey ◽  
...  
Keyword(s):  
Metal Transfer ◽  
Additive Manufacture ◽  
Cold Metal Transfer ◽  
Cold Metal

Experimental study on the effect of pressure and flow rate on cavitation in a poppet throttle valve

2019 ◽  
Vol 72 (5) ◽  
pp. 629-636
Author(s):  
Jian Zhang ◽  
Tingting Luo
Keyword(s):  
Flow Rate ◽  
Pressure Difference ◽  
High Speed ◽  
High Speed Camera ◽  
Experimental Conditions ◽  
Content Type ◽  
Experimental Support ◽  
Throttle Valve ◽  
Set Up

Purpose The purpose of this paper is to study the variation of cavitation scale with pressure and flow in poppet throttle valve, to obtain the cavitation scale under pressure and flow conditions and to provide experimental support for the research of suppressing throttle valve cavitation and cavitation theory. Design/methodology/approach A hydraulic cavitation platform was set up, a valve was manufactured with highly transparent PMMA material and a high-speed camera was used to observe the change in cavitation scale. Findings Through experiments, it is found that the pressure difference between inlet and outlet of throttle valve affects the cavitation scale, and the more the pressure difference is, the easier the cavitation will be formed. Under the condition of small pressure difference, the cavitation is not obvious and reducing the pressure difference can effectively suppress the cavitation; the flow rate also affects the cavitation scale, the smaller the flow rate, the more difficult the cavitation will be formed and the lower the flow rate, the more the cavitation will be suppressed. Research limitations/implications Because of the magnification factor of the high-speed camera lens, the morphology of smaller bubbles cannot be observed in this study, and the experimental conditions need to be improved in the follow-up study. Originality/value This study can provide experimental support for the study of throttle valve cavitation suppression methods and cavitation theory.

High-speed impact assessment for composite air inlet

2019 ◽  
Vol 11 (5) ◽  
pp. 723-736
Author(s):  
Radek Doubrava ◽  
Martin Oberthor ◽  
Petr Bělský ◽  
Jan Raška
Keyword(s):  
Numerical Simulation ◽  
Composite Structure ◽  
High Speed ◽  
Numerical Models ◽  
Impact Resistance ◽  
High Speed Camera ◽  
Content Type ◽  
High Speed Impact ◽  
Air Inlet ◽  
Final Design

Purpose The purpose of this paper is to describe the approach for the design of a jet engine composite air inlet for a new generation of jet trainer aircraft from the perspective of airworthiness requirements regarding high-speed impact resistance. Design/methodology/approach Validated numerical simulation was applied to flat test panels. The final design was optimised and verified by validated numerical simulation and verified by testing on a full-scale demonstrator. High-speed camera measurement and non-destructive testing (NDT) results were used for the verification of the numerical models. Findings The test results of flat test panels confirmed the high durability of the composite structure during inclined high-speed impact with a near-real jet inlet load boundary condition. Research limitations/implications Owing to the sensitivity of the composite material on technology production, the results are limited by the material used and the production technology. Practical implications The application of flat test panels for the verification and tuning of numerical models allows optimised final design of the air inlet and reduces the risk of structural non-compliance during verification tests. Originality/value Numerical models were verified for simulation of the real composite structure based on high-speed camera results and NDT inspection after impact. The proposed numerical model was simplified for application in a real complex design and reduced calculation time.

Erratum to: Mechanisms of weld pool flow and slag formation location in cold metal transfer (CMT) gas metal arc welding (GMAW)

2017 ◽  
Vol 61 (6) ◽  
pp. 1287-1287 ◽  
Author(s):  
Md. R. U. Ahsan ◽  
Muralimohan Cheepu ◽  
Rouholah Ashiri ◽  
Tae-Hoon Kim ◽  
Chanyoung Jeong ◽  
...  
Keyword(s):  
Weld Pool ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Metal Transfer ◽  
Slag Formation ◽  
Cold Metal Transfer ◽  
Metal Arc Welding ◽  
Cold Metal

Fabrication of curved overhanging thin-walled structure with robotic wire and arc additive manufacturing (RWAAM)

2019 ◽  
Vol 47 (1) ◽  
pp. 102-110
Author(s):  
Yifeng Li ◽  
Xunpeng Qin ◽  
Qiang Wu ◽  
Zeqi Hu ◽  
Tan Shao
Keyword(s):  
Additive Manufacturing ◽  
Weld Pool ◽  
Industrial Robot ◽  
Curve Surface ◽  
Industrial Robots ◽  
Force Model ◽  
Content Type ◽  
Forming Characteristics ◽  
Thin Walled ◽  
Torch Angle

Purpose Robotic wire and arc additive manufacturing (RWAAM) is becoming more and more popular for its capability of fabricating metallic parts with complicated structure. To unlock the potential of 6-DOF industrial robots and improve the power of additive manufacturing, this paper aims to present a method to fabricate curved overhanging thin-walled parts free from turn table and support structures. Design/methodology/approach Five groups of straight inclined thin-walled parts with different angles were fabricated with the torch aligned with the inclination angle using RWAAM, and the angle precision was verified by recording the growth of each layer in both horizontal and vertical directions; furthermore, the experimental phenomena was explained with the force model of the molten pool and the forming characteristics was investigated. Based on the results above, an algorithm for fabricating curved overhanging thin-walled part was presented and validated. Findings The force model and forming characteristics during the RWAAM process were investigated. Based on the result, the influence of the torch orientation on the weld pool flow was used to control the pool flow, then a practical algorithm for fabricating curved overhanging thin-walled part was proposed and validated. Originality/value Regarding the fabrication of curved overhanging thin-walled parts, given the influences of the torch angles on the deposited morphology, porosity formation rate and weld pool flow, the flexibility of 6-DOF industrial robot was fully used to realize instant adjustment of the torch angle. In this paper, the deposition point and torch orientation of each layer of a robotic fabrication path was determined by the contour equation of the curve surface. By adjusting the torch angle, the pool flow was controlled and better forming quality was acquired.

Mechanisms of weld pool flow and slag formation location in cold metal transfer (CMT) gas metal arc welding (GMAW)

2017 ◽  
Vol 61 (6) ◽  
pp. 1275-1285 ◽  
Author(s):  
Md. R . U. Ahsan ◽  
Muralimohan Cheepu ◽  
Rouholah Ashiri ◽  
Tae-Hoon Kim ◽  
Chanyoung Jeong ◽  
...  
Keyword(s):  
Weld Pool ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Metal Transfer ◽  
Slag Formation ◽  
Cold Metal Transfer ◽  
Metal Arc Welding ◽  
Cold Metal

Modeling of Cold Metal Transfer Spot Welding of AA6061-T6 Aluminum Alloy and Galvanized Mild Steel

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Zhenghua Rao ◽  
Jiangwei Liu ◽  
Pei-Chung Wang ◽  
Yunxiao Li ◽  
Shengming Liao
Keyword(s):  
Mild Steel ◽  
Weld Pool ◽  
Spot Welding ◽  
Steel Surface ◽  
Metal Transfer ◽  
Upward Flow ◽  
Zinc Vapor ◽  
Cold Metal Transfer ◽  
Arc Pressure ◽  
Cold Metal

In this article, a three-dimensional (3D) transient unified model is developed to simulate the transport phenomena during the cold metal transfer (CMT) spot welding process of 1 mm thick aluminum AA6061-T6 and 1 mm thick galvanized mild steel (i.e., AISI 1009). The events of the CMT process are simulated, including arc generation and evolution; up-and-down movement of electrode, droplet formation and dipping into the weld pool; weld pool dynamics; zinc evaporation, and zinc vapor diffusion in the arc. The effects of the gap between the two workpieces and effects of zinc vapor evaporated from the steel surface on CMT process are studied. The results show that the arc temperature, velocity, and pressure keep changing during the CMT process, which is related to the variations of welding current, arc length, and zinc evaporation. It is found that the zinc evaporation leads to the extremely high arc pressure and the upward flow of zinc vapor near the steel surface, which would induce the arc instability and provide the drag force for the droplet impingement. The presence of the gap between the two workpieces can improve the expansion of the arc plasma, resulting in the smaller arc pressure and the more intensive upward flow of zinc vapor from the steel surface. The phenomena observed in the experiment are in agreement with the modeling results.

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