Analysis of Droplet Transfer and Arc Swing in “TIG + AC” Twin-Wire Cross Arc Additive Manufacturing

Round 1

Reviewer 1 Report

The experimental part (sections 2 and 3) are borne out by the high-speed camera observations of the cross-arc process. These sections offer good and new insight into the process of arc-based twin-wire additive manufacturing. The process is very complex and the discussion section describes this very complex process qualitatively and maybe somewhat oversimplified. It might be better to move the qualitative description into section three and remove the separate discussion section.

Author Response

Thanks very much for the detailed comments. We have benefited a lot from your advice. As for the shortcomings of the article, we have made corresponding modifications according to your review comments. As for your suggestions, we are also very recognized, and ready to adopt. Finally, thank you again for your comments.

 

1. The experimental part (sections 2 and 3) are borne out by the high-speed camera observations of the cross-arc process. These sections offer good and new insight into the process of arc-based twin-wire additive manufacturing. The process is very complex and the discussion section describes this very complex process qualitatively and maybe somewhat oversimplified. It might be better to move the qualitative description into section three and remove the separate discussion section.

Authors’ Response: We are grateful for the suggestion. You are right.We have moved the qualitative description of discussion section into section three and remove the separate. The Figs order and literatures have been modified correspondently.The part about droplet force analysis plays little role in this paper, so after deleting it, the topic of the article becomes more prominent. 

Reviewer 2 Report

The article is devoted to the actual topic - the additive production of functionally graded materials. This direction will significantly expand the operational characteristics of products due to the structure of the material with a directional gradient. This is an actual direction for modern metallurgy and metallurgy, and also has very good prospects for industrial implementation.

 

1. The first section presents a literature review based on quite modern literary sources. The review is quite detailed.

2. In the second section, the details of the layer-by-layer sample growth experiment are given.

3. The third section presents new research results. The illustrations are well done. The description of the results is detailed.

4. The fourth section discusses the new results obtained, which reveals the mechanism of droplet transfer in layer-by-layer printing using two wires.

5. The fifth section draws conclusions based on the new results obtained.

 

Notes:

1. line 340. check the spelling of the sentence

Author Response

Thanks very much for the detailed comments. We have benefited a lot from your advice. As for the shortcomings of the article, we have made corresponding modifications according to your review comments. As for your suggestions, we are also very recognized, and ready to adopt. Finally, thank you again for your comments.

1. line 340. check the spelling of the sentence.

Authors’ Response: We are grateful for the suggestion. The last sentence in line340. really have some spelling fault.We have corrected the sentence in manuscript.

Reviewer 3 Report

1. The authors titled the paper "Analysis of Droplet Transfer and Arc Swing in "TIG+AC" Twin-wire Cross Arc Additive Manufacturing. In the introduction, the authors say that they are conducting comparative studies of the relationship between melt droplet transfer modes, arc behavior, process stability, and deposition quality. Such a study contributes to the optimization of the additive manufacturing parameters of the WAAM two-wire arc for the homogenization of metallic graded functional materials. However, further research by the authors is weakly related to the possibility of optimizing the structure and properties of workpieces obtained by additive technology. The article contains only an analysis of the change in the correctness of the shape and the ratio of the two geometric parameters of the resulting roller in one pass (height-width ratio) for different modes of mass transfer.

2. The study of the dependence of grain sizes in the microstructure of the deposited metal on the feed rates of the right and left wires, as well as on the parameters of the magnetic field on alternating current, is not included in the article.

3. The possibility of mass transfer control considered in the article is of interest rather for traditional surfacing than for additive technology. Droplets with a diameter of more than 2 mm and deposition layers with a width of 7-8 mm do not allow obtaining sufficiently accurate workpieces using additive technology with the minimum required volume of chip removal.

Author Response

Thanks very much for the detailed comments, and the reviewer's recognition and identification are appreciated very much. Your comments and suggestions will be useful  for our further study. The detailed answers are below with the review's comments.

1. The authors titled the paper "Analysis of Droplet Transfer and Arc Swing in "TIG+AC" Twin-wire Cross Arc Additive Manufacturing. In the introduction, the authors say that they are conducting comparative studies of the relationship between melt droplet transfer modes, arc behavior, process stability, and deposition quality. Such a study contributes to the optimization of the additive manufacturing parameters of the WAAM two-wire arc for the homogenization of metallic graded functional materials. However, further research by the authors is weakly related to the possibility of optimizing the structure and properties of workpieces obtained by additive technology. The article contains only an analysis of the change in the correctness of the shape and the ratio of the two geometric parameters of the resulting roller in one pass (height-width ratio) for different modes of mass transfer.

Authors’ Response: Thanks for your comments. This study is a series of research projects, we have done some basic research work, also published some articles on double wire additive manufacturing to manufacture gradient material process and microstructure,but that is not enough. "Huang J, Liu G, Yu X, et al. Characterization of nickel-titanium alloy graded materials using double wire alternating current cross arc additive manufacturing. Journal of Alloys and Compounds, 2022, 910: 164912." provides some explanation and analysis of the tissue properties of Ti-Ni.Maybe your concern question could be answer in the paper.The focus of this paper is the research on droplet transition form and cross arc stability in process.The arc stability is a direct factor on shaping quality of deposition.So,the deposition quality mentioned in the introduction refers to shaping quality, not means internal tissue and properties.

2. The study of the dependence of grain sizes in the microstructure of the deposited metal on the feed rates of the right and left wires, as well as on the parameters of the magnetic field on alternating current, is not included in the article.

Authors’ Response: Thanks for your comments.You are right.Indeed, the intensity of alternating magnetic field generated by AC current is an important parameter affecting the arc oscillation, which is exactly what we will do next. Subsquently, we will study the influence of AC current,frequency and magnetic field intensity on arc swing and droplet transition, so as to provide a complete process parameter database for dual-wire arc additive manufacturing. However, as a preliminary research work, we will publish the phased research results first, hoping to get guidance and suggestions from wise peers like you.

3. The possibility of mass transfer control considered in the article is of interest rather for traditional surfacing than for additive technology. Droplets with a diameter of more than 2 mm and deposition layers with a width of 7-8 mm do not allow obtaining sufficiently accurate workpieces using additive technology with the minimum required volume of chip removal.

Authors’ Response: Thanks for your comments. For the production accuracy, we will further improve the additive manufacturing accuracy by controlling the process transfer behavior as well as the process stability in the subsequent work. In terms of control, we will try to introduce deep reinforcement learning and other control means, which is also in progress simultaneously. We will also use this process for surface modification and in-situ alloying studies. We look forward to your continued interest in our research.