An Experimental Investigation on the Material Removal Rate and Surface Roughness of a Hybrid Aluminum Metal Matrix Composite (Al6061/SiC/Gr)
, Harish Kumar Garg 2, Sthitapragyan Maharana 1, Anchal Yadav 3, Rasmeet Singh 4, Pragyansu Maharana 1, Tien V. T. Nguyen 5, Sudesh Yadav 6 and M. K. Loganathan 7Round 1
Reviewer 1 Report
A solidly written article. Suggestions for improvement are as follows:
- Is it necessary to use abbreviations in the article title?
- Highlight the scientific benefit of this research at the end of the Introduction section.
- The EDM parameters considered in this work are peak current, voltage, pulse-on time and tool material. Since not all parameters of the EDM process are included in the research, the authors should clarify why they chose only some parameters. Further elaborate your choice in the article.
- The Taguchi method was applied for optimization. Explain your choice. The Taguchi method has advantages but also disadvantages. Compare the Taguchi method to other optimization methods (GA, PSO, etc.). What your research gained and what it lost with the use of the Taguchi method.
- How did you choose the EDM process parameters levels (current, pulse-on time, voltage)? Why these levels? Further elaborate on your choice.
- Estimate the measurement uncertainty for the obtained experimental data (table 4).
- Sensitivity analysis and / or uncertainty analysis would certainly increase the quality of research.
- The article lacks Discussion section. The results should be discussed in this section. Also it would be desirable to compare the results of this study with the results of previous research. Everything must be scientifically commented and discussed. The physics or the science behind the experiments needs to be clarified with the interpretation of the results.
- The conclusions should also state the limitations of this research.
Author Response
Thank you very much for providing your valuable feedback on this paper. We appreciate your comments that are very helpful for the revision of this article. Below please find the answers and actions taken to address these comments.
Comment 1: Is it necessary to use abbreviations in the article title?
Response: I/we have revised and updated the title of the article.
Comment 2: Highlight the scientific benefit of this research at the end of the Introduction section.
Response: Thank you for pointing this out. I/We agree with this comment. So, I/we updated the scientific benefit of this research at the end of the introduction section.
Comment 3: The EDM parameters considered in this work are peak current, voltage, pulse-on time and tool material. Since not all parameters of the EDM process are included in the research, the authors should clarify why they chose only some parameters. Further elaborate your choice in the article.
Response: You have raised an important point here. The selection of these EDM process parameters was completed on the basis of the earlier findings available in the literature and the recommendations of our previous research.
Comment 4: The Taguchi method was applied for optimization. Explain your choice. The Taguchi method has advantages but also disadvantages. Compare the Taguchi method to other optimization methods (GA, PSO, etc.). What your research gained and what it lost with the use of the Taguchi method.
Response: I/We agree with this point. The selection of Taguchi’s experimental design approach was done after carefully reviewed all the other optimization technique.
Comment 5: How did you choose the EDM process parameters levels (current, pulse-on time, voltage)? Why these levels? Further elaborate on your choice.
Response: You have raised an important point here. To select the significant levels of designated process parameters, a pilot study was carried out, where the effects of different levels of process parameters on output parameters (MRR, SR) were individually investigated. Based on the results of pilot experiments, the resulting set of parameters with the specific values have been selected for the design of the final experiments.
Comment 6: Estimate the measurement uncertainty for the obtained experimental data (table 4).
Response: I/We agree with this and have fixed this point.
Comment 7: Sensitivity analysis and / or uncertainty analysis would certainly increase the quality of research.
Response: Thanks for this suggestion. I/we will definitely consider these points in the next paper/research. Thanks.
Comment 8: The article lacks Discussion section. The results should be discussed in this section. Also it would be desirable to compare the results of this study with the results of previous research. Everything must be scientifically commented and discussed. The physics or the science behind the experiments needs to be clarified with the interpretation of the results.
Response: You have raised an important point here. So, I/we revised and updated more significant data here in this section. The scientific reasons behind the interpretation of the results have been added in this section now.
Comment 9: The conclusions should also state the limitations of this research.
Response: You have raised an important point here. I/We have fixed this point and added the limitation of this research in future scope part.
Reviewer 2 Report
In this paper, the optimum process parameters for EDM of new mixed aluminum matrix com-18 composite (AIMMC) were determined by experimental method, which is of certain significance. It is recommended that before accepting publication, consider the following recommendations:
1) Compared with the previous materials, the advantages of the new materials need to be highlighted.
2) In Figure 2, the machining samples of all experiments need to be given.
3)The evaluation index of MRR does not need to be given.
4) What is the basis for selecting the level of process parameters such as current in Table 3?
5) In Figures 3 and 5, more SEM photos need to be given to support the point of view of the paper.
6) Discussion requires a separate section.
7) The innovation of this paper needs to be strengthened.
8) There are few references in the last three years.
Author Response
Thank you very much for providing your valuable feedback on this paper. We appreciate your comments that are very helpful for the revision of this article. Below please find the answers and actions taken to address these comments.
Comment 1: Compared with the previous materials, the advantages of the new materials need to be highlighted.
Response: Thank you for pointing this out. I/We agree with this and have fixed this point. Please check section 2.1.
Comment 2: In Figure 2, the machining samples of all experiments need to be given.
Response: I/We agree with this and have fixed this point.
Comment 3: The evaluation index of MRR does not need to be given.
Response: I/We agree with this and have removed this part.
Comment 4: What is the basis for selecting the level of process parameters such as current in Table 3?
Response: You have raised an important point here. The selection of these EDM process parameters was completed on the basis of the earlier findings available in the literature and the recommendations of our previous research. Further, to select the significant levels of designated process parameters, a pilot study was carried out, where the effects of different levels of process parameters on output parameters (MRR, SR) were individually investigated. Based on the results of pilot experiments, the resulting set of parameters with the specific values have been selected for the design of the final experiments.
Comment 5: In Figures 3 and 5, more SEM photos need to be given to support the point of view of the paper.
Response: You have raised an important point here. Unfortunately, I/we have only two figures of the workpiece before machining as shown in Figure 3, but I/we have added more SEM photos in Figure 5. Please check.
Comment 6: Discussion requires a separate section.
Response: You have raised an important point here. So, I/we revised and updated more significant data here in this section. The scientific reasons behind the interpretation of the results have been added in this section now.
Comment 7: The innovation of this paper needs to be strengthened.
Response: Silicon carbide always enhance the hardness of a composite material whereas Graphite improves the self-lubricating power of composite material. Therefore, the machinability of composite material is different from the other metals. Hence, this study will directly help to resolve all the influencing factors that can cause variations in the final results of machining of a composite material.
Comment 8: There are few references in the last three years.
Response: I/We agree with this and have fixed this point.
Reviewer 3 Report
1) Please remove all acronyms from the title, abstract, keywords, and conclusions.
2) Please try to reduce acronyms all over the text of the manuscript.
3) Tables 3, 4, 5, 6, 7, 8, 9, 10. All values should have measuring units. Please reorganize the tables to simplify them. For example, there is not necessary to double the first row - SR or MRR since it is already written in the titles of the tables.
4) About SR. There is no such parameter in science. Please, provide what type of SR parameter you have presented in the table - Ra, Rz, Rtm, or others. There are plenty of them, according to ISO. Please take a look at https://www.researchgate.net/publication/346267620_Effect_of_Cavitation_Erosion_Wear_Vibration_Tumbling_and_Heat_Treatment_on_Additively_Manufactured_Surface_Quality_and_Properties (Tables 5, 6) what types of surface roughness exist and can be shown in the paper devoted to the research of the specific surface roughness in correlation with exploitation properties of the part.
5) Figures 4, 6. Please remove frames and present them as separated graphs. I would not do the graph for material (copper, brass) but for the specific electrical resistance.
6) gm/min - what is it?
7) Figure 3, please provide conditions of machining and material.
8) Figure 1 does not present any new knowledge.
9) All equations should have mentioned sources.
10) Almost all the references are out of date. Only 3 of them are related to the publications published in the last three years. Please enlarge the quantity of the actual publications (2019-2021) up to 50%.
11) The references should be international.
12) Lines 226-229 have no relation to current research since you have not developed this composite within this study.
13) Lines 232-234, first it was never a problem to machine conductive materials; secondly, you have never researched the efficiency of EDM since you have introduced the criteria of the efficiency within this study.
14) Lines 235-239, this is not a conclusion since it is known without this study. The choice of the brass is typically grounded by the required improved mechanical properties, for example, as a wire during WEDM. Since copper has better than brass electrical conductivity, it is always better for EDM if there are no other restrictions to the material. Better can be only silver, but it much more expensive.
15) Lines 240-241 were never proven since you did not measure any temperature fields in the working area.
16) Lines 242-244. it is known without this study.
17) I did not find any particular problem that was solved within this study.
18) the conclusions should be countable.
Author Response
Thank you very much for providing your valuable feedback on this paper. We appreciate your comments that are very helpful for the revision of this article. Below please find the answers and actions taken to address these comments.
Comment 1: Please remove all acronyms from the title, abstract, keywords, and conclusions.
Response: Thank you for pointing this out. I/We have accordingly modified the title, abstract, keywords, and conclusions to emphasize this point..
Comment 2: Please try to reduce acronyms all over the text of the manuscript.
Response: Thank you for pointing this out. I/we have made the significant changes in the manuscript.
Comment 3: Tables 3, 4, 5, 6, 7, 8, 9, 10. All values should have measuring units. Please reorganize the tables to simplify them. For example, there is not necessary to double the first row - SR or MRR since it is already written in the titles of the tables.
Response: Thank you for pointing this out. I/We agree with this comment. Therefore, I/we have made significant changes in all the tables.
Comment 4: About SR. There is no such parameter in science. Please, provide what type of SR parameter you have presented in the table - Ra, Rz, Rtm, or others.
Response: In this work the average surface roughness (Ra) of machined samples was investigated with a precise surface roughness tester. Please check the text (Section 2.2).
Comment 5: Figures 4, 6. Please remove frames and present them as separated graphs. I would not do the graph for material (copper, brass) but for the specific electrical resistance.
Response: Thanks for this suggestion. I/we will definitely consider these points in the next paper/research. Thanks.
Comment 6: gm/min - what is it?.
Response: I/We agree with this and have fixed this point.
Comment 7: Figure 3, please provide conditions of machining and material.
Response: I/We have fixed this point.
Comment 8: Figure 1 does not present any new knowledge.
Response: I/We have fixed this point.
Comment 9: All equations should have mentioned sources.
Response: I/We agree with this and have fixed this point.
Comment 10: Almost all the references are out of date. Only 3 of them are related to the publications published in the last three years. Please enlarge the quantity of the actual publications (2019-2021) up to 50%.
Response: You have raised an important point here. So, I/we updated new references.
Comment 11: The references should be international.
Response: I/We agree with this and have fixed this point.
Comment 12: Lines 226-229 have no relation to current research since you have not developed this composite within this study.
Response: Thank you for pointing this out. But I/we actually compared the mechanical and tribological properties, please check section 2.1.
Comment 13: Lines 232-234, first it was never a problem to machine conductive materials; secondly, you have never researched the efficiency of EDM since you have introduced the criteria of the efficiency within this study.
Response: I/We have fixed this point.
Comment 14: Lines 235-239, this is not a conclusion since it is known without this study. The choice of the brass is typically grounded by the required improved mechanical properties, for example, as a wire during WEDM. Since copper has better than brass electrical conductivity, it is always better for EDM if there are no other restrictions to the material. Better can be only silver, but it much more expensive.
Response: I/We have fixed this point.
Comment 15: Lines 240-241 were never proven since you did not measure any temperature fields in the working area.
Response: Thank you for pointing this out. Actually, there I/we said that the high current and pulse duration are accountable for distributing the heat to the workpiece surfaces, which further produce craters and these craters lead the high surface roughness in machined surfaces.
Comment 16: Lines 242-244. it is known without this study.
Response: I/We have fixed this point.
Comment 17: I did not find any particular problem that was solved within this study
Response: Generally, most of the metals are considered homogeneous whereas metal composites are inhomogeneous due to the inclusion of other materials. These additions which differ from the base metal properties changes the machining behavior of the composite. Hence, investigate the machinability of such metal composite become essential to study the nature of the reinforcements. This study will directly help to resolve all the influencing factors that can cause variations in the final results of machining of a composite material.
Comment 18: The conclusions should be countable.
Response: I/We agree with this and have fixed this point.
Round 2
Reviewer 1 Report
The manuscript has been corrected, supplemented and updated.
Author Response
Thank you for accepting our manuscript. Thanks for your valuable time and inputs.
Reviewer 2 Report
The authors have revised the paper to improve the quality.
Author Response
Thank you for accepting our manuscript. Thanks for your valuable time and inputs.
Reviewer 3 Report
1) How many times did you repeat the experiment?
2) Level-3 - what does "-" mean? Was it produced without a tool?
3) Please add measuring units for equation 1.
4) Ra is measured in µm.
5) SNRA - what is it?
6) You can do one table from tables 9 and 10 if you show EDM factors in vertical columns.
7) Tables 5-10, Figures 4,6, 7, the mentioned parameters and factors have no measuring units.
8) Figure 7. Why for different EDM factors you have received similar Ra values? For which type of tool electrode was it received?
9) What kind of industrial application has the developed composite?
10) Table 8, I do not see any surface roughness parameter value.
11) How was the electrode attached to the machine tool holder?
12) How did you control the diameter of electrodes and the perpendicularity of the working end of the electrode?
13) One of the most interesting things for the industry. When we try to apply a known technology to unknown material, the discharge gap is researched. Did you measure it? If not, please measure it and add relevant data on the measuring method and equipment and the description of the results for both electrodes.
14) Lines 167-175 need explanation. How did you measure machining time? What was the depth of the machined holes?
15) In Figure 5, please add EDM factors used for machining this composite sample with which the current SEM images of the machined surfaces were obtained.
16) "high heat on the workpiece surfaces" - how much?
17) lines 296-97 are not related to the results achieved in the current study.
18) "To verify the effectiveness" - you can not conclude on the effectiveness since you did not introduce in your study any criterium of efficiency.
19) "the Taguchi (L18) technique is used" - about used techniques it is explained already in section 2 and the abstract.
20) Conclusion 1 was not drawn from the conducted study.
21) "the copper is an ideal " - it is not a conclusion since it is obvious without study.
22) " surface roughness" - you can not say in common "surface roughness," please add names of the ISO surface roughness parameters and their values.
23) "low surface roughness" - please add values.
24) Conclusion 4 is not a conclusion since it is known without this study. Higher current and pulse durations in all the known cases lead to higher surface roughness parameters such as Ra and Rz, Rtm, and larger steps between peaks.
25) I found no practical significance of the work for the industry in the conclusions.
26) The conclusions should have countable results; the previous comment was not resolved: "increases" and "decreases" - how much?
27) Tables 1 and 2 - did it was measured within the current study? If yes, please provide measuring equipment and tolerance of measurements.
Author Response
Thank you very much for providing the feedback. We appreciate your comments that were very helpful for the revision of this article.
Comment 1: How many times did you repeat the experiment?
Response: To ensure the validity of the results, each experiment is repeated three times. This point was made previously in the manuscript (Line 194-196)
Comment 2: Level-3 - what does "-" mean? Was it produced without a tool
Response: I/we used L18(2Ë„1 3Ë„3), which means that I/we had one factor (Tool) at 2 levels and 3 factors at 3 levels each, it is already explained in the manuscript (Line 177-178). "-" has been removed now.
Comment 3: Please add measuring units for equation 1.
Response: Please note that equation 1 contains no units. It is a mathematical expression that is used to calculate the signal-to-noise ratio.
Comment 4: Ra is measured in µm.
Response: YES, Ra is measured in micrometer (µm). (Line 171-173).
Comment 5: SNRA - what is it?
Response: SNRA means signal to noise ratio and same is mentioned in the manuscript.
Comment 6: You can do one table from tables 9 and 10 if you show EDM factors in vertical columns.
Response: We appreciate your bringing this to our attention and considering our suggestion. However, because the values of the parameters in both tables are distinct, it is preferable to present them separately.
Comment 7: Tables 5-10, Figures 4,6, 7, the mentioned parameters and factors have no measuring units.
Response: Thank you for pointing this out. This point has been resolved in revised manuscript.
Comment 8: Figure 7. Why for different EDM factors you have received similar Ra values? For which type of tool electrode was it received?
Response: After observing that when the current, voltage, and pulse duration are low, a smoother surface (less surface roughness) occurs significantly. Authors compared the effect of brass and copper electrodes on SR using the same EDM parameters; yes, there were a few errors in Figure 7, but we have corrected them in revised manuscript.
Comment 9: What kind of industrial application has the developed composite?
Response: The developed composite is a significant material for use in automobile disc braking systems; however, we are unable to disclose the results at this time due to the nature of our ongoing research. (Line 130-132)
Comment 10: Table 8, I do not see any surface roughness parameter value.
Response: Authors have fixed this point in revised manuscript.
Comment 11: How was the electrode attached to the machine tool holder?
Response: The work piece and tool holding devices are used to maintain the original positions of the workpiece and tool during EDM machining. However, we are unable to incorporate all of these fundamental elements into the manuscript to maintain the dignity of reputed journal.
Work Piece Holding Device Tool Holder
Comment 12: How did you control the diameter of electrodes and the perpendicularity of the working end of the electrode?
Response: After machined all the electrodes on a lathe machine a digital height gage was used to ensure the perpendicularity. Both the work piece and the tool holding devices adhere to ISO standards, further ensuring the quality of the machining process.
Comment 13: One of the most interesting things for the industry. When we try to apply a known technology to unknown material, the discharge gap is researched. Did you measure it? If not, please measure it and add relevant data on the measuring method and equipment and the description of the results for both electrodes.
Response: In our previous research [13] and pilot study we already studied this factor on another Al/SiC/Gr composite material using steel, copper and brass electrodes and found insignificant outcomes, therefore authors did not consider it here, however in our future study we will definitely consider this factor. .
Comment 14: Lines 167-175 need explanation. How did you measure machining time? What was the depth of the machined holes?
Response: We have fixed this point. The machining time was measured by a stopwatch. (Lines 165-166)
Comment 15: In Figure 5, please add EDM factors used for machining this composite sample with which the current SEM images of the machined surfaces were obtained.
Response: Thank you for pointing this out. We have corrected this error.
Comment 16: "high heat on the workpiece surfaces" - how much?
Response: We have corrected this error.
Comment 17: lines 296-97 are not related to the results achieved in the current study.
Response: Please check Section 3.2, it is quite clear there that how the statement in Lines 296-297 stands.
Comment 18: "To verify the effectiveness" - you can not conclude on the effectiveness since you did not introduce in your study any criterium of efficiency.
Response: We have corrected this error.
Comment 19: "the Taguchi (L18) technique is used" - about used techniques it is explained already in section 2 and the abstract.
Response: We have corrected this error.
Comment 20: Conclusion 1 was not drawn from the conducted study.
Response: I/we actually compared the mechanical and tribological properties of Al6061/SiC/Gr, Al6061/SiC, and Al6061, please check Section 2.1, to understand Conclusion 1.
Comment 21: "the copper is an ideal " - it is not a conclusion since it is obvious without study.
Response: As we have studied two different electrodes (brass and copper) for MRR of Al6061/SiC(12%)/Gr(5%) composite and found that copper electrode is better than brass, therefore authors mentioned that for this particular composite material copper is an ideal EDM electrode.
Comment 22: " surface roughness" - you can not say in common "surface roughness," please add names of the ISO surface roughness parameters and their values.
Response: Here, we focused on arithmetical mean roughness value (Ra), please check Section 2.2, as this is already mentioned there.
Comment 23: "low surface roughness" - please add values
Response: Please, note that we are not comparing the SR values of this composite with other material or composite, we just investigated the selected EDM parameters effect on SR, and found that instead of copper the brass is a best electrode for low SR of Al6061/SiC(12%)/Gr(5%) composite.
Comment 24: Conclusion 4 is not a conclusion since it is known without this study. Higher current and pulse durations in all the known cases lead to higher surface roughness parameters such as Ra and Rz, Rtm, and larger steps between peaks.
Response: We have fixed this point.
Comment 25: I found no practical significance of the work for the industry in the conclusions.
Response: As previously stated, due to the material's superior mechanical and wear properties, Al6061/SiC/Gr can be used in automobile disc braking systems, which is why we conducted this study.
Comment 26: The conclusions should have countable results; the previous comment was not resolved: "increases" and "decreases" - how much?
Response: We have fixed this point.
Comment 27: Tables 1 and 2 - did it was measured within the current study? If yes, please provide measuring equipment and tolerance of measurements.
Response: For comparison of mechanical properties uniaxial tension and compression tests were conducted on a Universal testing machine (H001-1) and the hardness tests were performed on Rockwell Hardness Testing Machines (HR-430). Moreover, for the wear rate performance ball-on-flat sliding tests (according to ASTM G133) were conducted on a tribometer CETR UMT 2 equipped with a force sensor with a (+/- 0.05).
Round 3
Reviewer 3 Report
The authors thoughtfully reworked the article. The article can be published in the present form.
Author Response
Thank you so much for reviewing this manuscript. I/We are grateful for the valuable suggestions and comments of the reviewers.
