Creation of an Aluminum Alloy Template with a Surface Structure by Micro-Milling for Subsequent Replication of the Microstructure to Achieve Hydrophobicity

Round 1

Reviewer 1 Report

This manuscript has been characterized as an ‘article’.

-Therefore, in this case, it should contain appropriate new achievements and better explain the effects of the processing parameter and the processing mechanism.

-The abstract should follow the below structure:

(i) contextualization (positioning of the scenario to be evaluated), (ii) formulation of the research question, (iii) methodology, (iv) presentation of results, and (v) conclusion (scientific contribution).

-The introduction should make clear what new information this research introduces to the literature and the applications in the industry.

-The mechanism of micromachining should be explained better.

-The processing parameters' effects and analysis should be demonstrated better. It is not enough only to produce data. We should explain them properly, too.

-Conclusions should generalize the results and report the limits of this research.

-The reference’s format should follow the journal style.

NA

Author Response

First of all, thank you very much for your helpful comments and insights on our work. We appreciate it very much.

Here is a comment on the mentioned notes:

1) This manuscript has been characterized as an ‘article’. Therefore, in this case, it should contain appropriate new achievements and better explain the effects of the processing parameter and the processing mechanism.

The article paid attention to the possibilities of structure design, production, comparison of production technologies, replication of the original surface structure, which has not yet been made and described. The individual steps tested the manufacturing possibilities, brought new possibilities to the field of micro-milling application and the results obtained will serve for further research in this field with the intention of application to technical practice.

2)The abstract should follow the below structure:(i) contextualization (positioning of the scenario to be evaluated), (ii) formulation of the research question, (iii) methodology, (iv) presentation of results, and (v) conclusion (scientific contribution).
The abstract was modified according to the mentioned structure.

3)The introduction should make clear what new information this research introduces to the literature and the applications in the industry.
New information from the research has now been incorporated into the abstract. Further details can be found in the final section of the paper. The introduction of the paper provides a follow-up to the experimental part of the paper with the last paragraph relating to the main content of the research.

4)The mechanism of micromachining should be explained better.
The main aim of the article was not to describe in detail the already known production technology. The article focuses on a detailed description of production procedures, used equipment, machines, tools and analysis of the achieved results.

5)The processing parameters' effects and analysis should be demonstrated better. It is not enough only to produce data. We should explain them properly, too.
The used production parameters, tools and others do not allow the development of complex dependencies between individual variable elements. In case of problems, e.g. failure to reach the prescribed parameter size, this fact was described and the possible influencing phenomenon/parameter was pointed out. Due to 1 set of production conditions, attention was paid to the detailed description of the data obtained. In case of further research this comment will be taken into account.

6)Conclusions should generalize the results and report the limits of this research.
The conclusion of the paper briefly describes and summarizes the results achieved with comments on the individual areas addressed. The limitations of the research arise from the reported data obtained during structure fabrication and subsequent replication.

7)The reference’s format should follow the journal style.
In checking as part of this review, I was unable to find any flaws within the reference format. Can you please elaborate on what you mean specifically? Thank you.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript discusses the development of a microstructure based on a natural structure pattern of hydrophobic properties using micro-milling technology.

While the authors have made considerable research effort, the presentation of the paper and the results must be proved.  Additionally make the following corrections to the manuscript: 

Comment :

1、In Sentence 296, ”The cutting conditions were determined according to the tool manufacturer's recommendations“, the authors used the experimental cutting parameters combination, please explain why don’t use Taguchi method which is more scientific.

2、In Sentence 302, “It was possible to produce the microstructure with a selected set of parameters (material to be machined, cutting tool, cutting conditions, dimensions of the structure)”, please explain why chose EN AW 7075. It will be more persuasive if compare wth other material.

3、”In the case of the fabrication of surface structures on planar surfaces, PLA technology appears to be a more accurate and faster technology“. So, please explain why prone to use micro-milling technology for the fabrication of a microstructure.

4. Others, please add number for every component figre in Figure.2\3\8\9\10\11\13\16.

Author Response

First of all, thank you very much for your helpful comments and insights on our work. We appreciate it very much.

Here is a comment on the mentioned notes:

1)In Sentence 296, ”The cutting conditions were determined according to the tool manufacturer's recommendations“, the authors used the experimental cutting parameters combination, please explain why don’t use Taguchi method which is more scientific.
In the experimental part, we completely trusted the recommended cutting parameters from the manufacturer, who has much more extensive data and know-how than our scientific team. This paper is a pilot research in this area. In case of future higher volume production, the use of Taguchi method is encouraged, for the experimental purposes of our research we did not consider this method due to 1 set of cutting conditions.

2)In Sentence 302, “It was possible to produce the microstructure with a selected set of parameters (material to be machined, cutting tool, cutting conditions, dimensions of the structure)”, please explain why chose EN AW 7075. It will be more persuasive if compare wth other material.
Due to the nature of the experiment - the initial contact with this technology, we have drawn on the findings of other scientific papers, see similar commentary on this area in the paper. The EN AW 7075 material was an ideal input material for learning the principles and context of micro-milling technology and, moreover, it is a very accessible and widely used technical material in practice. Further research is considering the use and comparison of a larger set of machined materials - steel, aluminium alloys, composite materials and others.

3)”In the case of the fabrication of surface structures on planar surfaces, PLA technology appears to be a more accurate and faster technology“. So, please explain why prone to use micro-milling technology for the fabrication of a microstructure.
The mention of a more precise and faster technology is linked to a situation where the production conditions and parameters are tuned, stabilized and can be applied to the production of only surface structures on planar surfaces, not on general surfaces. When applied to general surfaces and surface structures, the two technologies cannot be compared and micro milling clearly has its own role and importance. Further information on the issue of setting individual parameters when using PLA and setting the production process depending on price vs. performance/quality parameters is guarded know-how that cannot be further specified

4)Others, please add number for every component figre in Figure.2\3\8\9\10\11\13\16.

Pictures 2, 3, 8, 9, 13, 16 – edited.

Pictures 10, 11 – are printscreens from 1 measuring window from the used software. In both cases it is one figure.

Reviewer 3 Report

The topic of the paper of replicating bionic structures by micro milling followed by silicon impression can be interesting.
The results are presented in a clear and comprehensible way.

The presented research design is kept very simple, just one set of process parameters are used for the micro milling process. The authors didn’t analyse if the replication quality of the micro milling or silicone impression process could be improved. I.e., the workpiece quality should be compared to the one produced by state of the art micro milling machine tools and, respectively or, in current research works. Also, the influence of the milled negative form on the quality of the following impression process for generating the silicone positive model should be analysed. 

The relevance of the PLA process for the presented research is not shown in the paper. As it allows for a better replication of the structure, it could be used as a reference for the silicone impression process.

Finally, the authors should validate their results in terms of the papers topic, i.e., the capability of the replicated structures regarding hydrophobicity. Please provide some information whether, or, to which extend, the objective could already be reached. 

Author Response

First of all, thank you very much for your helpful comments and insights on our work. We appreciate it very much.

Here is a comment on the mentioned notes:

1)The presented research design is kept very simple, just one set of process parameters are used for the micro milling process. The authors didn’t analyse if the replication quality of the micro milling or silicone impression process could be improved. I.e., the workpiece quality should be compared to the one produced by state of the art micro milling machine tools and, respectively or, in current research works. Also, the influence of the milled negative form on the quality of the following impression process for generating the silicone positive model should be analysed.

A deeper analysis of the improvement of the quality of the machined specimen or silicon replica is planned in the framework of further research together with the modification of geometrical parameters and the application of a larger set of cutting conditions in an attempt to optimize the results obtained in relation to the quality of the machined surface structure profile. Comparison with state-of-the-art milling machines was not the essence of this research. In order to compare the results obtained, the PLA laser machining technology used in practice was deliberately chosen and the results obtained were then compared. The milling of the negative shape structure was deliberately chosen to ensure the greatest possible stability of the surface structure and to eliminate the loss of part of the surface shape (burrs, tool chatter and removal of thin unstable parts of the profile) and to eliminate the intermediate step in the creation of the original structure by replication. What effects of milled negative shape do you think should be analysed?

2)The relevance of the PLA process for the presented research is not shown in the paper. As it allows for a better replication of the structure, it could be used as a reference for the silicone impression process.

PLA is mentioned in order to compare the achieved accuracy of chip technology with the unconventional technology, which is widely used in the creation of surface structures. The samples after replication using PLA technology showed a closed and unformed structure that did not allow the creation of a complete replica (surface structure placed in the surface) due to poor venting of the surface structure. Further research will take this aspect into account and any reference samples will respect the aspect of venting.

3)Finally, the authors should validate their results in terms of the papers topic, i.e., the capability of the replicated structures regarding hydrophobicity. Please provide some information whether, or, to which extend, the objective could already be reached.

The replicated structures/samples made using the silicone decal kit were tested for hydrophobicity as part of the research, as can be seen in Figure 17. Furthermore, testing the functional properties of the structures directly on machined samples with positive structures is encouraged.

Round 2

Reviewer 1 Report

Accept

Author Response

Thank you for amending each point and approving it for publication.

We greatly appreciate your response.