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Peer-Review Record

Performance Evaluation of MQCL Hard Milling of SKD 11 Tool Steel Using MoS2 Nanofluid

Metals 2019, 9(6), 658; https://doi.org/10.3390/met9060658
Reviewer 1: Anonymous
Reviewer 2: David Johnson
Reviewer 3: Paweł Twardowski
Reviewer 4: Anonymous
Metals 2019, 9(6), 658; https://doi.org/10.3390/met9060658
Received: 20 May 2019 / Revised: 28 May 2019 / Accepted: 3 June 2019 / Published: 5 June 2019

Round  1

Reviewer 1 Report

1) What is new being presented in this article? Put this information in the abstract.

2) Please incorporate more appropriate references, for example,

a) paper, "Turning of brasses using minimum quantity of lubricant (MQL) and flooded lubricant conditions", Materials and Manufacturing Processes, Taylor & Francis, 22, Nº1, (2007), 45-50.

b) paper, "Experimental studies on drilling of aluminium (AA 1050) under dry, minimum quantity of lubricant and flood-lubricated conditions", Journal of Engineering Manufacture, Proc Instn Mech Engrs Part

B, IMech, vol 220, 10, (2006), 1605-1611.

c) paper, "Optimal MQL and cutting conditions determination for desired surface roughness in turning of brass using genetic algorithms", Machining Science and Technology, Taylor & Francis, 16, 2, (2012), 304-

320.

d) paper "A note on the use of the minimum quantity lubrication (MQL) system in turning", Industrial Lubrication and Tribology, Emerald, 67, 3, (2015), 256-261.

e) paper, "Recent developments in sustainable manufacturing of gears: a review", Journal of Cleaner Production, Elsevier Sc., 112, (2016), 3320-3330.

f) paper "The effect of minimum quantity of lubrication in intermittent turning of magnesium on vibration signals ", Measurement, Elsevier Sc., 94, (2016), 338-343.

g) book, Sustainable Manufacturing, ISTE-Wiley, London, 2010 ISBN: 978-1-84821-212-1

h) book, Green Manufacturing Processes and Systems, Springer, Heidelberg, 2013, ISBN: 978-3-642-

33791-8

and others of Metals and other international journals.

3) A deeper discussion of the results obtained is necessary. In the discussion of the results development, it is very important to emphasize points of agreement or disagreement between results in this work and others cited in references part of manuscript.

4) Improve the conclusions.


Author Response

RESPONSE TO THE REVIEWER 1

We are very grateful for the reviews provided by the editors and each of the external reviewers of this manuscript. Please see below, our detailed response to comments.

 

1) What is new being presented in this article? Put this information in the abstract.

Answer:

- The abstract was rewritten by following the reviewer’s comments

2) Please incorporate more appropriate references, for example,

a) paper, "Turning of brasses using minimum quantity of lubricant (MQL) and flooded lubricant conditions", Materials and Manufacturing Processes, Taylor & Francis, 22, Nº1, (2007), 45-50.

b) paper, "Experimental studies on drilling of aluminium (AA 1050) under dry, minimum quantity of lubricant and flood-lubricated conditions", Journal of Engineering Manufacture, Proc Instn Mech Engrs Part B, IMech, vol 220, 10, (2006), 1605-1611.

c) paper, "Optimal MQL and cutting conditions determination for desired surface roughness in turning of brass using genetic algorithms", Machining Science and Technology, Taylor & Francis, 16, 2, (2012), 304-320.

d) paper "A note on the use of the minimum quantity lubrication (MQL) system in turning", Industrial Lubrication and Tribology, Emerald, 67, 3, (2015), 256-261.

e) paper, "Recent developments in sustainable manufacturing of gears: a review", Journal of Cleaner Production, Elsevier Sc., 112, (2016), 3320-3330.

f) paper "The effect of minimum quantity of lubrication in intermittent turning of magnesium on vibration signals ", Measurement, Elsevier Sc., 94, (2016), 338-343.

g) book, Sustainable Manufacturing, ISTE-Wiley, London, 2010 ISBN: 978-1-84821-212-1

h) book, Green Manufacturing Processes and Systems, Springer, Heidelberg, 2013, ISBN: 978-3-642-

33791-8

Answer:

- The suggested references have been cited in the revised manuscript in the ref. no 14-21.

3) A deeper discussion of the results obtained is necessary. In the discussion of the results development, it is very important to emphasize points of agreement or disagreement between results in this work and others cited in references part of manuscript.

Answer:

- The discussion of the results obtained is revised to make it deeper. The points of agreement or disagreement between results in this work and others cited in references part of manuscript are added to the revised paper.

The microstructure and profiles of machined surface captured by KEYENCE VHX-6000 Digital Microscope are investigated in Figs. 9-13 and reveal that MoS2 nanoparticle concentration has a strong effect. The novel observation is that the so-called “micro bubbles” remain on the machined surface, which increase with the rise of nanoparticle concentration shown in Figs. 12-13. The morphology of MoS2 nanoparticles is ellipsoidal and they possess the large surface area; therefore, they remain on the machined surface and form a thin protective film, which amplifies when increase the nanoparticle concentration [56] and contributes to form the tribofilm easily [38]. In addition, the oil mist containing MoS2 nanoparticles plays an important role in improving the cooling and lubricating characteristics in cutting zone [29, 53-55]. However, when the concentration of MoS2 nanoparticles in emulsion-based fluid rises to 0.8 wt%, it causes a negative effect on surface roughness [56]. Accordingly, the proper concentration in this case is 0.5 wt%, but more investigations need to study and explain this observation.

c. The effect of MQCL technique using MoS2 nanofluid on cutting performance

The cutting performance of normal carbide tools is significantly improved in hard milling due to the better cooling and lubricating effects of MQCL technique. In the previous studies, the cutting speed of carbide inserts increased to 110 m/min during MQL milling of hardened steel (50-52HRC), which is 2 times higher than the recommended cutting speed of the manufacturer [22, 57]. In this work, the carbide tools still show the effectiveness during cutting the difficult-to-cut steel with the range of hardness of 56-60 HRC while remaining the cutting speed of 110m/min, which is about 2.75 times higher than that of the manufacturer’s recommendation. It clearly reveals the superior cooling and lubricating effects on cutting zone by using MQCL method with MoS2 nanofluid.  From that, the manufacturing cost significantly reduces and the cutting applicability of carbide tools enlarges.   

 

4) Improve the conclusions.

Answer:

- The conclusions are improved by following the reviewer’s comment


Author Response File: Author Response.pdf

Reviewer 2 Report

I would suggest the authors modify the very long paragraphs in the introduction to improve the readability of the manuscript.

Figures 2, 4 and 5 are pictures of commercial products that are not particularly  unique and are unnecessary.

The lines Figure 10 are very faint in the copy I have. This figure should be improved..

 

Author Response

RESPONSE TO THE REVIEWER 2

We are very grateful for the reviews provided by the editors and each of the external reviewers of this manuscript. Please see below, our detailed response to comments.

 

I would suggest the authors modify the very long paragraphs in the introduction to improve the readability of the manuscript.

Answer:

- The introduction had been revised by following the reviewer’s comment

Figures 2, 4 and 5 are pictures of commercial products that are not particularly unique and are unnecessary.

Answer:

- Figures 2, 4 and 5 are deleted according to the reviewer’s comments.

The lines Figure 10 are very faint in the copy I have. This figure should be improved.

Answer:

The quality of Figure 10 is improved


Reviewer 3 Report

In the work, the authors used SKD 11 steel (European standard X153CrMoV12). By. the steel standard may have hardness within 58-64 HRC, depending on the tempering method. However, the authors state that this steel had a hardness of 52-60 HRC. How was SKD 11 steel with a hardness of 52 HRC obtained? A better solution would be if the authors used 3 different steels of the same type but with different hardness.

The main objection is that the variables were studied in a narrow range. This particularly applies to the cutting speed. Sintered carbides can be milled continuously hardened in the range of cutting speeds from 50 m / min to 500 m / min.

No information about the cutter diameter

The authors give: " The cutting performance is significantly improved by using MoS2 
 additives in emulsion-based fluid compared to dry" Process efficiency has not been studied. The greatest impact on the efficiency has feed speed and depth of cut, and these factors were constant     

Author Response

RESPONSE TO THE REVIEWER 3

We are very grateful for the reviews provided by the editors and each of the external reviewers of this manuscript. Please see below, our detailed response to comments.

 

In the work, the authors used SKD 11 steel (European standard X153CrMoV12). By. the steel standard may have hardness within 58-64 HRC, depending on the tempering method. However, the authors state that this steel had a hardness of 52-60 HRC. How was SKD 11 steel with a hardness of 52 HRC obtained? A better solution would be if the authors used 3 different steels of the same type but with different hardness.

Answer:

The heat treatment process of SKD 11 steel that the authors used to prepare the workpiece samples with different hardness as below:

Quenching: The steel samples are heated to about 1050°C in vacuum and kept at this temperature about 30 min. It is cooled by liquid nitrogen to reach the hardness of 62 HRC.

- Heating to 500°C, staying at this temperature for 4 hours to reach the hardness of 60 HRC.

- Heating to 550°C, staying at this temperature for 4 hours to reach the hardness of 56 HRC.

- Heating to 550°C, staying at this temperature for 6 hours to reach the hardness of 52 HRC.

The reason of using the hardness 52-56 HRC is added and discussed in detail in the revised paper

c. The effect of MQCL technique using MoS2 nanofluid on cutting performance

The cutting performance of normal carbide tools is significantly improved in hard milling due to the better cooling and lubricating effects of MQCL technique. In the previous studies, the cutting speed of carbide inserts increased to 110 m/min during MQL milling of hardened steel (50-52HRC), which is 2 times higher than the recommended cutting speed of the manufacturer [22, 57]. In this work, the carbide tools still show the effectiveness during cutting the difficult-to-cut steel with the range of hardness of 56-60 HRC while remaining the cutting speed of 110m/min, which is about 2.75 times higher than that of the manufacturer’s recommendation. It clearly reveals the superior cooling and lubricating effects on cutting zone by using MQCL method with MoS2 nanofluid.  From that, the manufacturing cost significantly reduces and the cutting applicability of carbide tools enlarges.   

 

The main objection is that the variables were studied in a narrow range. This particularly applies to the cutting speed. Sintered carbides can be milled continuously hardened in the range of cutting speeds from 50 m / min to 500 m / min.

Answer:

 

The cutting speed is studied and chosen in a narrow range because this study is developed from the previous works. Please see the following chart for machining conditions of this type of carbide tools (https://wix.lamina-tech.ch/img/catalog/1237.pdf).

                                             

The reason of using the range of cutting speed is added and discussed in detail in the revised paper

c. The effect of MQCL technique using MoS2 nanofluid on cutting performance

The cutting performance of normal carbide tools is significantly improved in hard milling due to the better cooling and lubricating effects of MQCL technique. In the previous studies, the cutting speed of carbide inserts increased to 110 m/min during MQL milling of hardened steel (50-52HRC), which is 2 times higher than the recommended cutting speed of the manufacturer [22, 57]. In this work, the carbide tools still show the effectiveness during cutting the difficult-to-cut steel with the range of hardness of 56-60 HRC while remaining the cutting speed of 110m/min, which is about 2.75 times higher than that of the manufacturer’s recommendation. It clearly reveals the superior cooling and lubricating effects on cutting zone by using MQCL method with MoS2 nanofluid.  From that, the manufacturing cost significantly reduces and the cutting applicability of carbide tools enlarges.   

 

No information about the cutter diameter

Answer:

Tool holder type with the designation SHIJIE BAP 400R-50-22-4T with the diameter of 50 mm was used.

The authors give: "The cutting performance is significantly improved by using MoS2 additives in emulsion-based fluid compared to dry" Process efficiency has not been studied. The greatest impact on the efficiency has feed speed and depth of cut, and these factors were constant 

Answer:

The sentence had revised to: “The surface roughness, surface microstructure, and surface profile of machined surface are better under MQCL technique using MoS2 additives in emulsion-based fluid when compared to dry, MQL pure fluid, and MQCL pure fluid.”

The process efficiency as well as the impact of feed speed and depth of cut did not discussed in this paper. Please let us to put them to the future work.


Author Response File: Author Response.pdf

Reviewer 4 Report

The paper presents an ecologically very important issue, i.e. the introduction of nanoparticles in emulsion mist (MQCL method). The paper is original and present interesting information. Strong side of this paper is a research character. The following are a few minor comments on this paper:

1. Please delete Fig. 2. A picture of the packaging of the tiles does not really bring any scientific value to this work.

2. In the text of chapter 2.1, please specify the tool designation, angles, type of coating and thickness.

3. In the introduction, the authors formulated the research problem very well. However, from the reader's perspective, it is recommended to add a paper on MoS2 nanoparticles:

- Experimental study on the eff ect of nanoparticle concentration on the lubricating property of nanofl
uids for MQL grinding of Ni-based alloy. J. Mater. Process. Technol., 232, (2016), s. 100–115.

The authors described the research of individual researchers very well. Please also add an item that speaks about the importance of the size of the droplets in relation to the rate of evaporation within 1 s:

- Research emulsion mist generation in the conditions of minimum quantity cooling lubrication (MQCL). Teh. Vjesn. – Tech. Gaz., 22, 5 (2015), s. 1213–1218.

or the overall evaluation of the MQCL method:

- Effects of extreme pressure and anti-wear additives on surface topography and tool wear during MQCL turning of AISI 1045 steel. Journal of Mechanical Science and Technology - 2018, Vol. 32, no. 2, s. 1585-1591.

4. In section 2.3.1, instead of ml/min, state the flow rate in ml/h. In addition, if possible, indicate the size of the nanoparticles to be introduced.

5. Please use the markings according to the standard, i.e. for the roughness parameter Ra, for the cutting speed Vc.

6. All variables in the article, please write in italic style.

7. The abstract is expected to include a brief digest of the research, that is, new methods, results, concepts and conclusions only. Please avoid including background information.

Author Response

RESPONSE TO THE REVIEWER 4

We are very grateful for the reviews provided by the editors and each of the external reviewers of this manuscript. Please see below, our detailed response to comments.

 

The paper presents an ecologically very important issue, i.e. the introduction of nanoparticles in emulsion mist (MQCL method). The paper is original and present interesting information. Strong side of this paper is a research character. The following are a few minor comments on this paper:

1. Please delete Fig. 2. A picture of the packaging of the tiles does not really bring any scientific value to this work.

Answer:

- Fig. 2 was deleted by following the reviewer’s comment.

2. In the text of chapter 2.1, please specify the tool designation, angles, type of coating and thickness.

Answer:

The technical specification of milling inserts was specified in the paper as below

The APMT 1604 PDTR LT30 PVD submicron carbide inserts of LAMINA Technologies (made in Switzerland) with flank angle of 11°, nose radius of 0.66 mm, and TiAlN coating layer was utilized.

The thickness of coating layer is not provided by the manufacturer, so we cannot put this into the paper.

 

3. In the introduction, the authors formulated the research problem very well. However, from the reader's perspective, it is recommended to add a paper on MoS2 nanoparticles:

- Experimental study on the effect of nanoparticle concentration on the lubricating property of nanofl
uids for MQL grinding of Ni-based alloy. J. Mater. Process. Technol., 232, (2016), s. 100–115.

Answer:

- The suggested references have been cited in the revised manuscript in the ref no. 29.

The authors described the research of individual researchers very well. Please also add an item that speaks about the importance of the size of the droplets in relation to the rate of evaporation within 1 s:

- Research emulsion mist generation in the conditions of minimum quantity cooling lubrication (MQCL). Teh. Vjesn. – Tech. Gaz., 22, 5 (2015), s. 1213–1218.

Answer:

- The suggested references have been cited in the revised manuscript in the ref no. 38.

 

or the overall evaluation of the MQCL method:

- Effects of extreme pressure and anti-wear additives on surface topography and tool wear during MQCL turning of AISI 1045 steel. Journal of Mechanical Science and Technology - 2018, Vol. 32, no. 2, s. 1585-1591.

Answer:

- The suggested references have been cited in the revised manuscript in the ref no. 41.

4. In section 2.3.1, instead of ml/min, state the flow rate in ml/h. In addition, if possible, indicate the size of the nanoparticles to be introduced.

Answer:

- The unit of flow rate is converted to ml/h.

- The size of the nanoparticles is introduced in section 2.1

“MoS2 nanoparticles made by Luoyang Tongrun Info Technology Co., Ltd with the size of 30nm (average) were used”

5. Please use the markings according to the standard, i.e. for the roughness parameter Ra, for the cutting speed Vc.

Answer:

- The paper had revised according to the reviewer’s comments

6. All variables in the article, please write in italic style.

Answer:

- All variables in the article were written in italic style.

7. The abstract is expected to include a brief digest of the research, that is, new methods, results, concepts and conclusions only. Please avoid including background information.

Answer:

- The abstract was rewritten by following the reviewer’s comments


Author Response File: Author Response.pdf

Round  2

Reviewer 1 Report

No comments

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