Wire arc additive manufacturing (WAAM) is a well-established additive manufacturing method that produces 3D profiles. A better deposition efficiency can be achieved by understanding the parameters that may influence the geometry of the bead. This paper provides a review that focuses on the factors that may influence the formation of the 3D profile. The included factors are the flow pattern of the molten pool after deposition, the built structure and orientation, the heat input and cooling conditions, the welding parameters, and other uncertainties. This review aims to facilitate a better understanding of these factors and achieve the optimum geometry of the 3D parts produced. According to the literature, the behavior of molten pools is identified as one of the major factors that can impact the deposition efficiency of a bead and govern its geometry. The review indicated that the flow behavior of the molten pool and the geometry of the deposited bead are significantly affected by most welding parameters, such as torch angle, wire travel speed, filler feed rate, and cooling conditions. Furthermore, this paper incorporates the technology utilized for comprehending the behaviors of the molten pool, as it constitutes an integral component of the control strategy. It has been concluded that automated planning and strategy are necessary to ensure efficient deposition by controlling those factors. The integration of artificial intelligence could bring benefits in planning to address the variation and complexity of shapes.

• Abe, T., Kaneko, J., & Sasahara, H. (2020). Thermal sensing and heat input control for thin-walled structure building based on numerical simulation for wire and arc additive manufacturing. Additive Manufacturing, 35, Article 101357. https://doi.org/10.1016/j.addma.2020.101357

• Aldalur, E., Veiga, F., Suárez, A. R., Bilbao, J., & Lamíkiz, A. (2020). High deposition wire arc additive manufacturing of mild steel: Strategies and heat input effect on microstructure and mechanical properties. Journal of Manufacturing Processes, 58, 615-626. https://doi.org/10.1016/j.jmapro.2020.08.060

• Bai, X., Colegrove, P. A., Ding, J., Zhou, X., Diao, C., Bridgeman, P., Hönnige, J., Zhang, H., & Williams, S. (2018). Numerical analysis of heat transfer and fluid flow in multilayer deposition of PAW-based wire and arc additive manufacturing. International Journal of Heat and Mass Transfer, 124, 504-516. https://doi.org/10.1016/j.ijheatmasstransfer.2018.03.085

• Benakis, M., Costanzo, D., & Patran, A. (2020). Current mode effects on weld bead geometry and heat affected zone in pulsed wire arc additive manufacturing of Ti-6-4 and Inconel 718. Journal of Manufacturing Processes, 60, 61-74. https://doi.org/10.1016/j.jmapro.2020.10.018

• Cadiou, S., Courtois, M., Carin, M., Berckmans, W., & Masson, P. (2020). 3D heat transfer, fluid flow and electromagnetic model for cold metal transfer wire arc additive manufacturing (Cmt-Waam). Additive Manufacturing, 36, Article 101541. https://doi.org/10.1016/j.addma.2020.101541

• Chaturvedi, M., Scutelnicu, E., Rusu, C. C., Mistodie, L. R., Mihailescu, D., & Subbiah, A. V. (2021). Wire arc additive manufacturing: Review on recent findings and challenges in industrial applications and materials characterization. Metals, 11(6), Article 939. https://doi.org/10.3390/met11060939

• Chaudhary, C. S., Kashish, & Khanna, P. (2021). Effect of welding parameters on the weld bead profile of submerged arc welded low carbon steel plates. IOP Conference Series: Materials Science and Engineering, 1126(1), Article 012022. https://doi.org/10.1088/1757-899x/1126/1/012022

• Chen, S., Chi, Y., Zhang, P., & Shi, Y. (2020). Mechanism to reduce the porosity during argon arc welding of aluminum alloys by changing the arc angle. Metals, 10(9), Article 1121. https://doi.org/10.3390/met10091121

• Chernovol, N., Lauwers, B., & Van Rymenant, P. (2020). Development of low-cost production process for prototype components based on Wire and Arc Additive Manufacturing (WAAM). Procedia CIRP, 95, 60-65. https://doi.org/10.1016/j.procir.2020.01.188

• Clijsters, S., Craeghs, T., Buls, S., Kempen, K., & Kruth, J. (2014). In situ quality control of the selective laser melting process using a high-speed, real-time melt pool monitoring system. The International Journal of Advanced Manufacturing Technology, 75(5-8), 1089-1101. https://doi.org/10.1007/s00170-014-6214-8

• Cunningham, C., Flynn, J. M., Shokrani, A., Dhokia, V., & Newman, S. T. (2018). Invited review article: Strategies and processes for high quality wire arc additive manufacturing. Additive Manufacturing, 22, 672-686. https://doi.org/10.1016/j.addma.2018.06.020

• Ding, D., He, F., Yuan, L., Pan, Z., Wang, L., & Ros, M. (2021). The first step towards intelligent wire arc additive manufacturing: An automatic bead modelling system using machine learning through industrial information integration. Journal of Industrial Information Integration, 23, Article 100218. https://doi.org/10.1016/j.jii.2021.100218

• Dinovitzer, M., Chen, X., Laliberté, J., Huang, X., & Frei, H. (2019). Effect of wire and arc additive manufacturing (WAAM) process parameters on bead geometry and microstructure. Additive Manufacturing, 26, 138-146. https://doi.org/10.1016/j.addma.2018.12.013

• Ermakova, A., Mehmanparast, A., Ganguly, S., Razavi, J., & Berto, F. (2020). Investigation of mechanical and fracture properties of wire and arc additively manufactured low carbon steel components. Theoretical and Applied Fracture Mechanics, 109, Article 102685. https://doi.org/10.1016/j.tafmec.2020.102685

• Feucht, T., Waldschmitt, B., Lange, J., & Erven, M. (2021). 3D‐printing with steel: Additive manufacturing of a bridge in situ. Ce/Papers, 4(2-4), 1695-1701. https://doi.org/10.1002/cepa.1475

• Gao, F., Zhao, W., Gao, Q., Zhang, M., Sun, E., Liu, Z., & Jiang, P. (2017). Study on the influencing factors in the forming process of arc additive manufacturing. Development & Application of Materials, 2, 59-63.

• Giarollo, D. F., Mazzaferro, C. C. P., & Mazzaferro, J. A. E. (2022). Comparison between two heat source models for wire-arc additive manufacturing using GMAW process. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 44, 1-13. https://doi.org/10.1007/s40430-021-03307-8

• Gierth, M., Henckell, P., Ali, Y., Scholl, J., & Bergmann, J. P. (2020). Wire arc additive manufacturing (WAAM) of aluminum alloy AlMg5Mn with energy-reduced gas metal arc welding (GMAW). Materials, 13(12), Article 2671. https://doi.org/10.3390/ma13122671

• Greebmalai, J., & Warinsiriruk, E. (2020). Multi-heat input technique for aluminum WAAM using DP-GMAW process. In AIP Conference Proceedings (Vol. 2279, No. 1). AIP Publishing. https://doi.org/10.1063/5.0022954

• Guo, M., Jia, C., Zhou, J., Liu, W., & Wu, C. (2020). Investigating the generation process of molten droplets and arc plasma in the confined space during compulsively constricted WAAM. Journal of Materials Processing Technology, 275, Article 116355. https://doi.org/10.1016/j.jmatprotec.2019.116355

• Hackenhaar, W., Mazzaferro, J. A. E., Montevecchi, F., & Campatelli, G. (2020). An experimental-numerical study of active cooling in wire arc additive manufacturing. Journal of Manufacturing Processes, 52, 58-65. https://doi.org/10.1016/j.jmapro.2020.01.051

• Halisch, C., Radel, T., Tyralla, D., & Seefeld, T. (2020). Measuring the melt pool size in a wire arc additive manufacturing process using a high dynamic range two-colored pyrometric camera. Welding in the World, 64(8), 1349-1356. https://doi.org/10.1007/s40194-020-00892-5

• Han, Q., Li, Y., & Zhang, G. (2018). Online control of deposited geometry of multi-layer multi-bead structure for wire and arc additive manufacturing. In Transactions on Intelligent Welding Manufacturing: Volume I No. 1 2017 (pp. 85-93). Springer. https://doi.org/10.1007/978-981-10-5355-9_7

• Hauser, T., Reisch, R. T., Breese, P., Lutz, B., Pantano, M., Nalam, Y., Bela, K., Kamps, T., Volpp, J., & Kaplan, A. (2021). Porosity in wire arc additive manufacturing of aluminium alloys. Additive Manufacturing, 41, Article 101993. https://doi.org/10.1016/j.addma.2021.101993

• Hauser, T., Reisch, R. T., Seebauer, S., Parasar, A., Kamps, T., Casati, R., Volpp, J., & Kaplan, A. (2021). Multi-material wire arc additive manufacturing of low and high alloyed aluminium alloys with in-situ material analysis. Journal of Manufacturing Processes, 69, 378-390. https://doi.org/10.1016/j.jmapro.2021.08.005

• Hejripour, F., Valentine, D. T., & Aidun, D. K. (2018). Study of mass transport in cold wire deposition for wire arc additive manufacturing. International Journal of Heat and Mass Transfer, 125, 471-484. https://doi.org/10.1016/j.ijheatmasstransfer.2018.04.092

• Henckell, P., Gierth, M., Ali, Y., Reimann, J., & Bergmann, J. P. (2020). Reduction of energy input in wire arc additive manufacturing (WAAM) with gas metal arc welding (GMAW). Materials, 13(11), Article 2491. https://doi.org/10.3390/ma13112491

• Hofman, J., Pathiraj, B., Van Dijk, J., Lange, D., & Meijer, J. (2012). A camera based feedback control strategy for the laser cladding process. Journal of Materials Processing Technology, 212(11), 2455-2462. https://doi.org/10.1016/j.jmatprotec.2012.06.027

• Hu, D., & Kovacevic, R. (2003). Sensing, modeling and control for laser-based additive manufacturing. International Journal of Machine Tools & Manufacture, 43(1), 51-60. https://doi.org/10.1016/s0890-6955(02)00163-3

• Huang, J., Li, Z., Yu, S., Yu, X., & Fan, D. (2022). Real-time observation and numerical simulation of the molten pool flow and mass transfer behavior during wire arc additive manufacturing. Welding in the World, 66(3), 481-494. https://doi.org/10.1007/s40194-021-01214-z

• Jafari, D., Vaneker, T. H., & Gibson, I. (2021). Wire and arc additive manufacturing: Opportunities and challenges to control the quality and accuracy of manufactured parts. Materials & Design, 202, Article 109471. https://doi.org/10.1016/j.matdes.2021.109471

• Ji, F., Qin, X., Hu, Z., Xiong, X., Ni, M., & Wu, M. (2022). Influence of ultrasonic vibration on molten pool behavior and deposition layer forming morphology for wire and arc additive manufacturing. International Communications in Heat and Mass Transfer, 130, Article 105789. https://doi.org/10.1016/j.icheatmasstransfer.2021.105789

• Jia, C., Liu, W., Chen, M., Guo, M., Wu, S., & Chen, W. (2020). Investigation on arc plasma, droplet, and molten pool behaviours in compulsively constricted WAAM. Additive Manufacturing, 34, Article 101235. https://doi.org/10.1016/j.addma.2020.101235

• Karayel, E., & Bozkurt, Y. (2020). Additive manufacturing method and different welding applications. Journal of Materials Research and Technology, 9(5), 11424-11438. https://doi.org/10.1016/j.jmrt.2020.08.039

• Karmuhilan, M., & Sood, A. K. (2018). Intelligent process model for bead geometry prediction in WAAM. Materials Today: Proceedings, 5(11), 24005-24013. https://doi.org/10.1016/j.matpr.2018.10.193

• Kozamernik, N., Bračun, D., & Klobčar, D. (2020). WAAM system with interpass temperature control and forced cooling for near-net-shape printing of small metal components. The International Journal of Advanced Manufacturing Technology, 110(7-8), 1955-1968. https://doi.org/10.1007/s00170-020-05958-8

• Laghi, V., Palermo, M., Gasparini, G., Girelli, V. A., & Trombetti, T. (2021). On the influence of the geometrical irregularities in the mechanical response of Wire-and-Arc Additively Manufactured planar elements. Journal of Constructional Steel Research, 178, Article 106490. https://doi.org/10.1016/j.jcsr.2020.106490

• Le, V. T., Si, D., & Hoang, Q. H. (2020). Effects of cooling conditions on the shape, microstructures, and material properties of SS308L thin walls built by wire arc additive manufacturing. Materials Letters, 280, Article 128580. https://doi.org/10.1016/j.matlet.2020.128580

• Lee, H., Kim, J., Pyo, C., & Kim, J. (2020). Evaluation of bead geometry for aluminum parts fabricated using additive Manufacturing-Based Wire-Arc welding. Processes, 8(10), Article 1211. https://doi.org/10.3390/pr8101211

• Leicher, M., Kamper, S., Treutler, K., & Wesling, V. (2020). Multi-material design in additive manufacturing - Feasibility validation. Welding in the World, 64(8), 1341-1347. https://doi.org/10.1007/s40194-020-00887-2

• Li, F., Chen, S., Shi, J., Zhao, Y., & Tian, H. (2018). Thermoelectric Cooling-Aided bead geometry regulation in wire and Arc-Based additive manufacturing of thin-walled structures. Applied Sciences, 8(2), Article 207. https://doi.org/10.3390/app8020207

• Li, Z., Ma, G., Zhao, G., Yang, M., & Xiao, W. (2018). Weave bead welding based wire and arc additive manufacturing technology. In Recent Advances in Intelligent Manufacturing: First International Conference on Intelligent Manufacturing and Internet of Things and 5th International Conference on Computing for Sustainable Energy and Environment, IMIOT and ICSEE 2018, Proceedings, Part I 5 (pp. 408-417). Springer. https://doi.org/10.1007/978-981-13-2396-6_38

• Lin, Z., Song, K., & Yu, X. (2021). A review on wire and arc additive manufacturing of titanium alloy. Journal of Manufacturing Processes, 70, 24-45. https://doi.org/10.1016/j.jmapro.2021.08.018

• Liu, J., Xu, Y., Yu, G., Hou, Z., & Chen, S. (2020). Wire and arc additive manufacturing of metal components: A review of recent research developments. The International Journal of Advanced Manufacturing Technology, 111(1-2), 149-198. https://doi.org/10.1007/s00170-020-05966-8

• Liu, W., Jia, C., Guo, M., & Gao, J. (2019). Compulsively constricted WAAM with arc plasma and droplets ejected from a narrow space. Additive Manufacturing, 27, 109-117. https://doi.org/10.1016/j.addma.2019.03.003

• Mai, D. S., Doan, T. K., & Paris, H. (2021). Wire and arc additive manufacturing of 308L stainless steel components: Optimization of processing parameters and material properties. Engineering Science and Technology, an International Journal, 24(4), 1015-1026. https://doi.org/10.1016/j.jestch.2021.01.009

• Manokruang, S., Vignat, F., Museau, M., & Limousin, M. (2021). Process parameters effect on weld beads geometry deposited by wire and arc additive manufacturing (WAAM). In Advances on Mechanics, Design Engineering and Manufacturing III: Proceedings of the International Joint Conference on Mechanics, Design Engineering & Advanced Manufacturing, JCM 2020 (pp. 9-14). Springer International Publishing. https://doi.org/10.1007/978-3-030-70566-4_3

• Montevecchi, F., Venturini, G., Grossi, N., Scippa, A., & Campatelli, G. (2018). Heat accumulation prevention in wire-arc-additive-manufacturing using air jet impingement. Manufacturing Letters, 17, 14-18. https://doi.org/10.1016/j.mfglet.2018.06.004

• Mu, H., Pan, Z., Li, Y., He, F., Polden, J., & Xia, C. (2021). MIMO model predictive control of bead geometry in wire arc additive manufacturing. In 2021 IEEE 11th Annual International Conference on CYBER Technology in Automation, Control, and Intelligent Systems (CYBER) (pp. 169-174). IEEE Publishing. https://doi.org/10.1109/cyber53097.2021.9588331

• Nagasai, B. P., Malarvizhi, S., & Balasubramanian, V. (2021). Mechanical properties of wire arc additive manufactured carbon steel cylindrical component made by gas metal arc welding process. Journal of the Mechanical Behavior of Materials, 30(1), 188-198. https://doi.org/10.1515/jmbm-2021-0019

• Navarro, M., Matar, A., Diltemiz, S. F., & Eshraghi, M. (2021). Development of a low-cost wire arc additive manufacturing system. Journal of Manufacturing and Materials Processing, 6(1), Article 3. https://doi.org/10.3390/jmmp6010003

• Ni, M., Zhou, Y., Hu, Z., Qin, X., Xiong, X., & Ji, F. (2023). Forming optimization for WAAM with weaving deposition on curved surfaces. International Journal of Mechanical Sciences, 252, Article 108366. https://doi.org/10.1016/j.ijmecsci.2023.108366

• Ogino, Y., Asai, S., & Hirata, Y. (2018). Numerical simulation of WAAM process by a GMAW weld pool model. Welding in the World, 62(2), 393-401. https://doi.org/10.1007/s40194-018-0556-z

• Ou, W., Mukherjee, T., Knapp, G., Wei, Y., & DebRoy, T. (2018). Fusion zone geometries, cooling rates and solidification parameters during wire arc additive manufacturing. International Journal of Heat and Mass Transfer, 127, 1084-1094. https://doi.org/10.1016/j.ijheatmasstransfer.2018.08.111

• Pan, Z., Ding, D., Cuiuri, D., Li, H., & Norrish, J. (2018). Arc welding processes for additive manufacturing: A review. Transactions on intelligent welding manufacturing, 1(1), 3-24. https://doi.org/10.1007/978-981-10-5355-9_1

• Panchagnula, J. S., & Simhambhatla, S. (2018). Manufacture of complex thin-walled metallic objects using weld-deposition based additive manufacturing. Robotics and Computer-Integrated Manufacturing, 49, 194–203. https://doi.org/10.1016/j.rcim.2017.06.003

• Pandey, P. K. (2019). Manufacturing of large metallic components through wire and arc additive manufacturing (WAAM) (Master thesis). Indian Institute of Technology Hyderabad, India. https://raiith.iith.ac.in/5599/1/Mtech_Thesis_TD1428_2019.pdf

• Parvez, S., Abid, М., Nash, D., Fawad, H., & Galloway, A. (2013). Effect of torch angle on arc properties and weld pool shape in stationary GTAW. Journal of Engineering Mechanics, 139(9), 1268-1277. https://doi.org/10.1061/(asce)em.1943-7889.0000553

• Paskual, A., Álvarez, P. G., & Suárez, A. R. (2018). Study on arc welding processes for high deposition rate additive manufacturing. Procedia CIRP, 68, 358-362. https://doi.org/10.1016/j.procir.2017.12.095

• Qin, Y., Qi, Q., Shi, P., Scott, P. J., & Jiang, X. (2021). Status, issues, and future of computer-aided part orientation for additive manufacturing. The International Journal of Advanced Manufacturing Technology, 115(5-6), 1295-1328. https://doi.org/10.1007/s00170-021-06996-6

• Reisgen, U., Sharma, R., Mann, S. M., & Oster, L. (2020). Increasing the manufacturing efficiency of WAAM by advanced cooling strategies. Welding in the World, 64(8), 1409-1416. https://doi.org/10.1007/s40194-020-00930-2

• Ríos, S., Colegrove, P. A., Martina, F., & Williams, S. (2018). Analytical process model for wire + arc additive manufacturing. Additive Manufacturing, 21, 651-657. https://doi.org/10.1016/j.addma.2018.04.003

• Rodrigues, T. A., Duarte, V. R., Miranda, R. M. M., Santos, T. G., & Oliveira, J. (2019). Current status and perspectives on Wire and Arc Additive Manufacturing (WAAM). Materials, 12(7), Article 1121. https://doi.org/10.3390/ma12071121

• Rosli, N. A., Alkahari, M. R., Ramli, F. R., Mat, S., & Yusof, A. A. (2019). Influence of process parameters on dimensional accuracy in GMAW based additive manufacturing. In Proceedings of Mechanical Engineering Research Day 2019 (pp. 7-9). CARe Publishing.

• Scotti, F. M., Teixeira, F. R., Da Silva, L. J., De Araújo, D. B., Reis, R. P., & Scotti, A. (2020). Thermal management in WAAM through the CMT Advanced process and an active cooling technique. Journal of Manufacturing Processes, 57, 23-35. https://doi.org/10.1016/j.jmapro.2020.06.007

• Shen, H., Deng, R., Liu, B., Tang, S., & Li, S. (2020). Study of the mechanism of a stable deposited height during GMAW-Based additive manufacturing. Applied Sciences, 10(12), Article 4322. https://doi.org/10.3390/app10124322

• Shi, J., Li, F., Chen, S., Zhao, Y., & Tian, H. (2019). Effect of in-process active cooling on forming quality and efficiency of tandem GMAW–based additive manufacturing. The International Journal of Advanced Manufacturing Technology, 101(5-8), 1349-1356. https://doi.org/10.1007/s00170-018-2927-4

• Su, C., & Chen, X. (2019). Effect of depositing torch angle on the first layer of wire arc additive manufacture using cold metal transfer (CMT). Industrial Robot-an International Journal, 46(2), 259-266. https://doi.org/10.1108/ir-11-2018-0233

• Su, C., Chen, X., Gao, C., & Wang, Y. (2019). Effect of heat input on microstructure and mechanical properties of Al-Mg alloys fabricated by WAAM. Applied Surface Science, 486, 431-440. https://doi.org/10.1016/j.apsusc.2019.04.255

• Tang, S., Wang, G., Huang, C., & Zhang, H. (2019). Investigation and control of weld bead at both ends in WAAM. In 2019 International Solid Freeform Fabrication Symposium (pp. 693-702). University of Texas at Austin. https://doi.org/10.26153/tsw/17307

• Teixeira, F. R., Scotti, F. M., Reis, R. P., & Scotti, A. (2021). Effect of the CMT advanced process combined with an active cooling technique on macro and microstructural aspects of aluminum WAAM. Rapid Prototyping Journal, 27(6), 1206-1219. https://doi.org/10.1108/rpj-11-2020-0285

• Van Thao, L. E. (2020). A preliminary study on gas metal arc welding-based additive manufacturing of metal parts. VNUHCM Journal of Science and Technology Development, 23(1), 422-429.

• Vázquez, L., Rodriguez, M. N., Rodriguez, I., & Álvarez, P. (2021). Influence of post-deposition heat treatments on the microstructure and tensile properties of TI-6AL-4V parts manufactured by CMT-WAAM. Metals, 11(8), Article 1161. https://doi.org/10.3390/met11081161

• Venkatarao, K. (2021). The use of teaching-learning based optimization technique for optimizing weld bead geometry as well as power consumption in additive manufacturing. Journal of Cleaner Production, 279, Article 123891. https://doi.org/10.1016/j.jclepro.2020.123891

• Vora, J., Pandey, R., Dodiya, P., Patel, V., Khanna, S., Vaghasia, V., & Chaudhari, R. (2023). Fabrication of multi-walled structure through parametric study of bead geometries of GMAW-based WAAM process of SS309L. Materials, 16(14), Article 5147. https://doi.org/10.3390/ma16145147

• Waldschmitt, B. (2019). Additive Manufacturing of a Bridge (Doctoral dissertation). Technische Universität Darmstadt, Darmstadt.

• Wang, C., Bai, H., Ren, C., Fang, X., & Lu, B. (2020). A comprehensive prediction model of bead geometry in wire and arc additive manufacturing. Journal of Physics: Conference Series, 1624(2), Article 022018. https://doi.org/10.1088/1742-6596/1624/2/022018

• Wang, S., Gu, H., Wang, W., Li, C., Ren, L., Wang, Z., Zhai, Y., & Ma, P. (2019). Study on microstructural and mechanical properties of an AL–CU–SN alloy wall deposited by double-wire arc additive manufacturing process. Materials, 13(1), Article 73. https://doi.org/10.3390/ma13010073

• Wang, Z., Zimmer-Chevret, S., Léonard, F., & Abba, G. (2022). Improvement strategy for the geometric accuracy of bead’s beginning and end parts in wire-arc additive manufacturing (WAAM). The International Journal of Advanced Manufacturing Technology, 118(7-8), 2139-2151. https://doi.org/10.1007/s00170-021-08037-8

• Waqas, A., Qin, X., Xiong, J., Chao, Y., & Fan, L. (2018). Impact toughness of components made by GMAW based additive manufacturing. Procedia Structural Integrity, 13, 2065-2070. https://doi.org/10.1016/j.prostr.2018.12.207

• Wu, B., Ding, D., Cuiuri, D., & Li, H. J. (2018a). Effects of heat accumulation on microstructure and mechanical properties of Ti6Al4V alloy deposited by wire arc additive manufacturing. Additive Manufacturing, 23, 151-160. https://doi.org/10.1016/j.addma.2018.08.004

• Wu, B., Ding, D., Cuiuri, D., Li, H. J., Xu, J., & Norrish, J. (2018b). A review of the wire arc additive manufacturing of metals: properties, defects and quality improvement. Journal of Manufacturing Processes, 35, 127-139. https://doi.org/10.1016/j.jmapro.2018.08.001

• Xiong, J., Li, Y., Li, R., & Yin, Z. (2018). Influences of process parameters on surface roughness of multi-layer single-pass thin-walled parts in GMAW-based additive manufacturing. Journal of Materials Processing Technology, 252, 128-136. https://doi.org/10.1016/j.jmatprotec.2017.09.020

• Xiong, J., Liu, Y., & Yin, Z. (2020). Passive vision measurement for robust reconstruction of molten pool in wire and arc additive manufacturing. Measurement, 153, Article 107407. https://doi.org/10.1016/j.measurement.2019.107407

• Xiong, J., Zhang, G., & Zhang, W. (2015). Forming appearance analysis in multi-layer single-pass GMAW-based additive manufacturing. The International Journal of Advanced Manufacturing Technology, 80(9-12), 1767-1776. https://doi.org/10.1007/s00170-015-7112-4

• Yuan, L., Pan, Z., Ding, D., He, F., Van Duin, S., Li, H. J., & Li, W. (2020). Investigation of humping phenomenon for the multi-directional robotic wire and arc additive manufacturing. Robotics and Computer-Integrated Manufacturing, 63, Article 101916. https://doi.org/10.1016/j.rcim.2019.101916

• Zeinali, M., & Khajepour, A. (2010). Height control in laser cladding using adaptive sliding mode technique: Theory and experiment. Journal of Manufacturing Science and Engineering-Transactions of the ASME, 132(4), Article 041016. https://doi.org/10.1115/1.4002023

• Zeng, Z., Cong, B., Oliveira, J., Ke, W., Schell, N., Peng, B., Qi, Z., Ge, F., Zhang, W., & Ao, S. (2020). Wire and arc additive manufacturing of a Ni-rich NiTi shape memory alloy: Microstructure and mechanical properties. Additive Manufacturing, 32, Article 101051. https://doi.org/10.1016/j.addma.2020.101051

• Zhong, Y., Zheng, Z., Li, J., & Wang, C. (2021). Fabrication of 316L nuclear nozzles on the main pipeline with large curvature by CMT wire arc additive manufacturing and self-developed slicing algorithm. Materials Science and Engineering: A, 820, Article 141539. https://doi.org/10.1016/j.msea.2021.141539