Numerical Estimation of the Geometry of the Deposited Layers during Direct Laser Deposition of Multi-Pass Walls

Round 1

Reviewer 1 Report

Very interesting appraoch for a fast calculation of DLD. Two major issues should be addressed to get the paper published:

• experiments show a clear influence of the material on the wall width, while theory gives not such an influence. This indicates a systematic error, which hsould be discussed in the text.
• while figure 13 gives a wall height of 16 mm, tables and plots give a wall height of ~8 mm. Where is the factor 2 coing from?

Author Response

Thank you for questions.

1. The factors influencing the wall width are described in the paragraphs below Figures 14 and 15 in Chapter 4 "Discussion".
2. For Figure 13, a description and process parameters have been added. The changes in Figure 13 are presented in Chapter 3.

Thank you for your review.

Reviewer 2 Report

The manuscript provide a thorough mathematical analysis of the metal deposition process based on analytical description of the heat transfer problem and bead geometry based on surface tension consideration.  The paper is worth to be published, but very extensive proof-reading of English is required. 

I have provided some comments for the authors and marked the places in the text to be re-edited in attached manuscript.  

Comments for author File: Comments.pdf

Author Response

I thank you for your comment.

You can see the corrected moments in the work.

Formula 1 has been fixed.

The functions f11 and f12 were described in more detail (p. 5).

The deposition strategy and hatch spasing were added in the paragraph before Table 1. For all experiments hatch spacing was 1.67 mm, the deposition strategy was unidirectional.

References to material properties have been added (Table 2).

The letter "s" in table 3 is a misprint.

Thank you for your review.

Reviewer 3 Report

        In this paper, the geometry of the deposited beads of the multi-channel multi-layer wall is numerically estimated. An analytical solution of the heat equation in a quasi-stationary formulation was used to calculate the temperature fields, and the shape of the deposited beads was described using capillary theory. The calculation results were verified by experiments, the error was not more than 10%, and the geometric shape of the multi-channel wall can be predicted with high precision. From this manuscript, the authors did a interesting work. Generally speaking, the structure of the paper is clearly, the figures and tables are specification. Therefore, I recommend it to be published just after addressing some issues.

Q1: In addition to introducing the calculation process of the algorithm, Section 2 should alsoalso include such content as the theory or method used in the experiment and the boundary conditions of the calculation model.  Moreover, the experimental materials and laser direct deposition parameters are best added to Section 2, rather than describing the experimental parameters shown in Table 1 in Section 3.

Q2: The authors explained the reason for the difference between experimental and calculated data in the discussion part, which involves the initial setting of the algorithm model, so what are the boundary conditions of the model?

Q3: The description of Figure 13 is too succinct. The information contained in this photo is important because it exhibits the comparison between the experimental data and calculated data of Ti-6Al-4V /CP. However, the authors did not describe this in detail.

Author Response

Thank you for questions.

1. Process parameters and material properties were transferred to Section 2.3
2. As an elementary heat source, a model of a point source moving along the surface of a semi-infinite body was used. The adiabatic boundary condition applies to all boundaries of the deposited wall.
3. For Figure 13, a description and process parameters have been added. The changes in Figure 13 are presented in Chapter 3.

Thank you for your review.

Round 2

Reviewer 1 Report

The explanation of the difference in width between experiments and simulaion are not very convincing. Please reconsider.

Are the simulations for the comparison in fig. 13 also using different materials as the experiments. Please add a comment.

Author Response

Thank you for questions.

1. The updated description is given in the paragraphs after Figures 14 and 15. The width of the deposition is influenced by many different factors. The description of these factors was not part of the study.
2. The properties of Ti-6Al-4V alloy were used for the calculation. The properties of Ti-6Al-4V and CP alloys differ only at room temperature. When heated, the values of the thermophysical properties are equalized. A comment was also added above Figure 13