Wear Mechanism of an AlCrN-Coated Solid Carbide Endmill Cutter and Machined Surface Quality under Eco-Friendly Settings during Open Slot Milling of Tempered JIS SKD11 Steel

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article contains good experimental material on testing various cutting methods of tempered JIS SKD11 steel at low cutting speeds 80 and 100 (m/min). Endmill with AlCrN PVD coating was used. The findings are important for cutting specific steel under strictly defined conditions. It was found that dry cutting is inferior in all characteristics to other methods, including the use of lubricants and coolants.

Based on this article, the reader may get the idea that dry cutting is an ineffective metalworking method. At the same time, dry cutting has proven its undeniable advantages during cutting of hard and tough steels. This effect is achieved by high-speed dry cutting with PVD coatings based on nonequilibrium complex nitrides. [German Fox-Rabinovich, Anatoly Kovalev, Iosif Gershman, Dmitry Wainstein, Myriam H. Aguirre, Danielle Covelli, Jose Paiva, Kenji Yamamoto, Stephen Veldhuis. Complex Behavior of Nano-Scale Tribo-Ceramic Films in Adaptive PVD Coatings under Extreme Tribological Conditions. Entropy 2018, 20, 989; doi:10.3390/e20120989. D. Wainstein, A. Kovalev. Tribooxidation as a way to improve the wear resistance of cutting tools. Coatings 2018, 8, 223; doi:10.3390/coatings8060223]. The 1 Introduction occupies 1/3 of the text of the article itself. And despite its enormous volume, it requires clarification about the place of this research in the problem of metalworking. The authors are requested to supplement the section with the information: “the choice of cutting speeds, type of protective wear-resistant coatings, type of lubricants depends on the cutting speed and mechanical properties of the material being processed. These factors are key conditions for realizing tribocompatibility of the cutting tool and the workpiece”.

Comment.

 

The information in lines 379-383 contains repetitions and the authors should make adjustments.

Author Response

Dear Reviewer 1

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The machinability of JIS SKD11 steel under different conditions was studied in this article. The research focused on cutting parameters, cooling methods, and relevant parameters for optimization through tool wear, surface roughness, cutting temperature, and microhardness assessments. The research methodology, innovation, and practicality are acceptable, but there are still some shortcomings in the article:

1. The second part contains too much content regarding material introduction and methods. It's suggested to explain only how to proceed and consider deleting excess information.

2. Section 3.1 describes the tool wear process or degradation modes under different machining conditions. However, drawing corresponding conclusions solely through observed scanning electron microscope images and collaborating with EDS to reveal them might be more reasonable.

3. Is the surface roughness you measured profile roughness?

4. In the third part, the distribution of subsections will be discussed; I believe that discussing cutting temperature first and then tools is crucial. Discussing wear, surface roughness, and microhardness is important as well. Since milling temperature is a dynamic response while the other three are resultant quantities, the temperature can be used while analyzing the other three results.

5. The conclusion lacks conciseness and readability, so it is recommended to modify it accordingly.

6. The format of the conclusion section needs to be checked.

 

Author Response

Dear Reviewer 2

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In my opinion, the manuscript should be substantially corrected.

General concerns:

1. There is no clear technical/scientific objective of the study set at the end of Introduction.
2. The manuscript starts with section Materials, Cutters, Machine, and Methodology for the Probing Trials., i.e. there is no attempt to formulate a scientific rationale behind the study.
3. The obtained results are valid only for the cutting conditions, including the cutting tool geometry and grade, and machining operation chosen for the test. Therefore, the obtained results have low significance for other applications. The is no justification why the cutting tool and tool material (not indicated in the manuscript) are selected for the study. When happens if another tool is used?
4. It is not clear why the authors used carbide tool for hard machining, particularly when the work material has high hardness (HRS58–60 as indicated in the manuscript). In this hardness range, a pCBN tool material is normally used as it has much greater wear resistance at high temperatures.

Particular concerns:

Introduction is too long. Many literature sources discussed in Introduction have no relation to hard machining. On the contrary, the most basic papers on the hard machining are not mentioned. For example: Nakayama K, Arai M, Kanda T (1988) Machining characteristic of hard materials. CIRP Annals – Manufacturing Technology 37: 89–92; Tönshoff HK, Arendt C, Ben Amor R (2000) Cutting of hardened steel. CIRP Annals – Manufacturing Technology 49(2): 547–566 and many others. They are well summarized in V.P. Astakhov, Machining of hard materials–definitions and industrial applications, in Machining of Hard Materials (Springer, London, 2011), pp. 1–32, where the essence of this process is clearly defined. Unfortunately, the authors do not account for this essence in their study.

The author used the term “feed rate” instead of “cutting feed.” The feed rate is measured in mm/min, i.e. is the speed of feed. The cutting feed is measured in mm/min, i.e. is the advance of the tool per its one revolution.

Figures 10 through 15 are not clear in terms of the particular part of the tool where the shown wear patterns are found. I would suggest to add the sketch of the tool with indication of this part.

The relevance and significance of the temperatures shown in figs. 18 and 19 are not clear.

Author Response

Dear Reviewer 3

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed many of my concerns, so I would recommend the manuscript for publishing.