Effect of Cutting Tool Structures on CFRP Interlaminar Drilling

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

the paper could be accepted for publication but after adressing the following remarks

• The percentage of plagiarism 33% is too high and should be reduced to less then 20% however the originality of the manuscript could be in question
• Authors need to highlight the novelty of their research in the abstract compared to what it is done in litterature.
• References analysed in the introductory section should contain new references (2022-2025) at the aim to sheck the novelty of the current research.
• difference between the two figures in fig 1 should be highlighted indicate if the orientation of the layers is the difference between the two drilling methods or other things
• section 2.1 the material mechanical characterisitcs should be drawn in a table.
• in figure 3 why this fluctuations in the reading of drilling forces is that vibrations or other things in the process?
• in figure 6 it is recommende to add a zoom in the contact zone to see better the damage
• figure 10 and 11. reduce the size of markers to improve the quality of the figure
• a section where the authors give the optimization and process parameters analysis should be added before the conclusion section.

Author Response

For the convenience of review, we have submitted our detailed responses to the reviewers as an attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

I have some questions

- Could you please provide details on the fabrication process of the CFRP specimens? (e.g., compression molding, resin infusion, manual layup, etc.)

- Please specify the exact type of carbon fiber and resin matrix used. This information is crucial for reproducibility and comparison with other studies.

- The paper mentions a multi-directional layup, but the specific sequence (e.g., [90°/45°/0°/-45°]15s) and the fiber volume fraction are not provided. These details are essential as they significantly influence the mechanical properties and, consequently, the drilling performance of the material. Could you please clarify this?

- The reviewer has carefully read your manuscript and was impressed by the interesting research findings. The reviewer would like to offer a suggestion that could further enhance the completeness of the paper. The reviewer believes that providing visual information on the cross-sectional structure of the CFRP material used in the experiment would greatly improve the readers' understanding. The reviewer would like to politely ask if you could include a representative cross-sectional image (e.g., an optical microscope or SEM image) that shows the fiber distribution, layup status, and any potential internal defects.  Such data would significantly contribute to increasing the reliability of your experimental results.

- How was the adhesion between the layers verified? How were the effects of interlaminar defects (delamination) on drilling damage considered?

- How was the effect of heat generated during the drilling process on the tool and material analyzed?

Author Response

For the convenience of review, we have submitted our detailed responses to the reviewers as an attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article presents an experimental study on interlaminar drilling of CFRP using four different tool geometries (twist drill, dagger drill, candlestick drill, and step drill). The analysis focuses on axial forces, outlet damage morphology, and the comprehensive damage factor. The aim of the work is to determine the relationship between tool geometry, machining parameters, and material damage. The topic is relevant and may provide important insights into the machinability of CFRP. However, the paper contains some inconsistencies and omissions that should be clarified, corrected, and supplemented.

1. Please clearly present the applications of the investigated laminates in mechanical engineering and machine construction. It should also be discussed whether such a laminate, in which drilled holes are made, would not constitute a weak point in the structure.

2. Table 2 presents the experimental plan, in which spindle speed and feed per revolution were adopted. However, these parameters do not fully represent the technological parameters commonly used in drilling processes. They should be corrected and replaced with process parameters: cutting speed vc (resulting from spindle speed) and feed per tooth fz, which directly affects the thickness of the cut layer h. These parameters should be consistently applied throughout the paper, both in the descriptions and in the figures.

3. Figure 3 shows the variation of axial force, while the authors labeled the vertical axis as Thrust force. The terminology should be unified. Moreover, the figures include the notation fitting data. The authors should provide the empirical equation used for data fitting. If, however, this is not fitting but rather a data filtering method, then the filtering procedure should be clearly described.

4. Figures 10 and 11 present maximum cutting force values, but confidence intervals are missing. The authors should clarify whether they analyzed single measurement points. It is necessary to explain how the maximum values were determined and why average maximum values from the drilling zone were not considered. It is recommended to present the results also in the form of box-plot diagrams, which would provide more statistical information about the drilling process. The results should be enriched with additional statistical analyses.

5. The conclusions need improvement. They should be more specific and include numerical results obtained from the experiments, rather than only qualitative descriptions.

Author Response

For the convenience of review, we have submitted our detailed responses to the reviewers as an attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Based on my review of the authors’ responses and the revised manuscript, it is clear that the authors have addressed the reviewers’ comments in a highly  comprehensive manner. The revisions are commendable, and I am in recommending the manuscript for publication.

Author Response

Reviewers' comments:

Based on my review of the authors’ responses and the revised manuscript, it is clear that the authors have addressed the reviewers’ comments in a highly  comprehensive manner. The revisions are commendable, and I am in recommending the manuscript for publication.

Author’s answer:

Thank you very much for your recognition of our study. Your professional comments during the review process have helped us improve the quality of our manuscript.

We would like to express our sincerest gratitude to you.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript has a minor lack of information: Expand Table 2 by including the additional parameters that you presented in the response letter. Also, the cutting speed vc should be expressed in m/min.

Author Response

1 Reviewers' comments:

Comments and Suggestions for Authors：

The manuscript has a minor lack of information: Expand Table 2 by including the additional parameters that you presented in the response letter. Also, the cutting speed vc should be expressed in m/min.

Author’s answer:

Thank you for your careful and professional comments. Thank you for pointing out our mistake. We have supplemented and corrected Table 2 in the revised manuscript based on your suggestions. As follows.

Table 2. Experimental parameters setting for CFRP interlaminar drilling.

Number	Spindle speed (r/min)	Feed rate (mm/r)	Cutting speed (m/min)	Feed per tooth (mm/z)
1	2000	0.04	0.08	0.02
2	2000	0.06	0.12	0.03
3	2000	0.08	0.16	0.04
4	2000	0.10	0.20	0.05
5	3000	0.04	0.12	0.02
6	3000	0.06	0.18	0.03
7	3000	0.08	0.24	0.04
8	3000	0.10	0.30	0.05
9	4000	0.04	0.16	0.02
10	4000	0.06	0.24	0.03
11	4000	0.08	0.32	0.04
12	4000	0.10	0.40	0.05
13	5000	0.04	0.20	0.02
14	5000	0.06	0.30	0.03
15	5000	0.08	0.40	0.04
16	5000	0.10	0.50	0.05

Please see page 4 in the revised manuscript in detail.

Author Response File: Author Response.pdf