Improvement of Analytical Model for Oblique Cutting—Part I: Identification of Mechanical Characteristics of Machined Material

Round 1

Reviewer 1 Report

The paper deals with the influence of the oblique cutting conditions on the mechanical response of the machined material. It combines analytical approach, experimental findings and numerical analysis in order to arrive at its final proposition.

The presentation is characterized by a detailed and exhaustive theoretical analysis of a phenomenon, that has been widely studied until now, and provides successfully with a new and original analysis procedure.

It is well organized and the results are clear and supported by experimental results satisfactorily.

In my opinion, the paper is acceptable as it is.

Author Response

Answers to the comments of Reviewer #1:

The authors are very grateful to Reviewer #1 for meticulously reviewing and interpreting the content of the paper.

Reviewer #1: The paper deals with the influence of the oblique cutting conditions on the mechanical response of the machined material. It combines analytical approach, experimental findings and numerical analysis in order to arrive at its final proposition.

The presentation is characterized by a detailed and exhaustive theoretical analysis of a phenomenon, that has been widely studied until now, and provides successfully with a new and original analysis procedure. It is well organized and the results are clear and supported by experimental results satisfactorily. In my opinion, the paper is acceptable as it is.

• The authors are very grateful to reviewer #1 for appreciating their study.

Reviewer 2 Report

The work by Storchak and Lekveishvili is interesting and presents new methods that might be appealing for some researchers in the journal's audience. However, prior to publication the authors need to address the following issues:

 

The introduction seems to touch upon the development of methods for creating and improving analytical models of orthogonal and oblique cutting. It also mentions the practical absence of recommendations on the choice of parameters with respect to analytical cutting models. However, the authors should ensure that the introduction provides a clear context for the study, highlighting the gap in the current literature that this research aims to address. Specifically, The authors should consider providing a chronological overview of the evolution of analytical models, highlighting key milestones and their implications. This would give readers a clearer understanding of the study's significance.

 

 

 

The methods section details the conditions and assumptions made during the study, such as the machined material being rigidly plastic and subject to strain-hardening. It also describes the power consumed in the cutting process and the formation of new surfaces during chip formation.

 

The methods seem to be described in detail, but the authors should ensure that any equipment, software, or specific procedures used are described in detail to allow for reproducibility. The manuscript doesn't delve deeply into the rationale behind choosing this specific design over others. A subsection discussing the rationale for the chosen research design, its advantages, and potential limitations would strengthen this section. The authors should consider adding subsections detailing the equipment and software used, calibration procedures, and any precautions taken to ensure data accuracy. Any potential sources of error or bias should also be discussed.

 

 

 

Alongside the raw data and figures, the authors should provide more commentary on the significance of each finding, any patterns observed, and potential implications.

 

The authors should ensure that the conclusions drawn are directly supported by the results and avoid overgeneralizing or making claims not backed by the data. Please adjust to avoid possible misleading statements. The authors should expand the conclusion section to discuss the study's broader significance, its potential impact on the field, and any recommendations for future research or practical applications.

 

The authors should consider revising the manuscript for clarity, ensuring that complex concepts are explained and that the language is accessible to a broader academic audience.

 

 

The command of the English language is acceptable and minor changes should be done prior to publication

 

Author Response

Answers to the comments of Reviewer #2:

The authors are very grateful to Reviewer #2 for meticulously reviewing and interpreting the content of the paper.

Reviewer #2:    The work by Storchak and Lekveishvili is interesting and presents new methods that might be appealing for some researchers in the journal's audience. However, prior to publication the authors need to address the following issues:

1. The introduction seems to touch upon the development of methods for creating and improving analytical models of orthogonal and oblique cutting. It also mentions the practical absence of recommendations on the choice of parameters with respect to analytical cutting models.

However, the authors should ensure that the introduction provides a clear context for the study, highlighting the gap in the current literature that this research aims to address.

Specifically, The authors should consider providing a chronological overview of the evolution of analytical models, highlighting key milestones and their implications. This would give readers a clearer understanding of the study's significance.

• The authors have clarified the study context and more clearly articulated the gap in published research on analytical cutting models, which the proposed study aims to address. In addition, the aim of the study is formulated. This is presented in the manuscript text (see lines 223-243). A chronological overview of the evolution of analytical cutting models in the table form is additionally presented in the manuscript text as recommended by the reviewer.

All changes carried out in the paper are marked in red font.

 

2. The methods section details the conditions and assumptions made during the study, such as the machined material being rigidly plastic and subject to strain-hardening. It also describes the power consumed in the cutting process and the formation of new surfaces during chip formation.

The methods seem to be described in detail, but the authors should ensure that any equipment, software, or specific procedures used are described in detail to allow for reproducibility. The manuscript doesn't delve deeply into the rationale behind choosing this specific design over others. A subsection discussing the rationale for the chosen research design, its advantages, and potential limitations would strengthen this section. The authors should consider adding subsections detailing the equipment and software used, calibration procedures, and any precautions taken to ensure data accuracy. Any potential sources of error or bias should also be discussed.

• The authors describe in sufficient detail the used equipment, characterize the machined material and cutting tools. Thermomechanical characteristics of the machined material and cutting inserts are given. Cutting tool geometry and cutting modes are described in detail. In addition, relevant references are provided. The used methods, the original analytical cutting model and the characterized software are described in detail and a flowchart of the software algorithm is given. This information is outlined in Section 3, "Materials and Methods," over seven pages of the paper, which is naturally limited in length. According to the authors, the detailed information presented enables readers to familiarize themselves with the analytical and numerical methods, used equipment and devices to perform experimental studies. In the event that in the reviewer's opinion the information presented is insufficient to replicate such studies, the authors very much ask the respected reviewer to point out specific gaps in the description. Naturally, the authors will endeavor to fill these particular gaps.

The aim of the suggested paper is to improve the analytical oblique cutting model through the determination and refinement of the input data, in particular the mechanical properties of the machined material. In order to achieve the above aim, the authors have used a specific research design. The design applied by the authors has been repeatedly validated. It ensures that the accuracy and reliability of the measured data are satisfactory for the intended aim. The used software tools provide reliable convergence of the numerical modeling results, as well as fast and reliable analytical calculations. The used cutting modes and conditions, tool parameters and initial state of workpieces correspond to the accepted and repeatedly used values in industry and in the research of cutting processes in the machining of structural heat-treated steels. These all characteristics of the study design are described in detail in Section 3, „Materials and Methods”, as mentioned above by the authors. Justifying the used research design, much less comparing it with other designs, is beyond the scope of the proposed paper. The authors are not developing a new study design and claim to do so in the proposed paper. The accuracy and reliability of the obtained results are shown with the results of the performed studies outlined in Section 4 "Results and Discussion" of the paper.

To clarify the above, the authors give a small example that relates to the calibration procedure. In accordance with Kistler's recommendation and established practice, the dynamometer used with piezoelectric measuring elements does not need any additional calibration by users. A data list is included with the dynamometer. Among other information, this list also includes the dynamometer's sensitivity value in the coordinate axes. This value is used in the measurement software package to convert an electrical analog signal into force units. However, to improve the reliability of the measurement of the cutting force components, the dynamometer used was additionally calibrated by static loading along the vector directions of the cutting force components.

The authors concede that some, minor, specific characteristics of the study design could have raised questions. If so, the authors very much ask the respected reviewer to inform them of these specific characteristics that need further explanation or justification. No doubt the authors will make all efforts to explain and/or justify these particular characteristics and will make changes to the manuscript as necessary.

 

3. Alongside the raw data and figures, the authors should provide more commentary on the significance of each finding, any patterns observed, and potential implications.

• Each obtained result, presented in the manuscript in the form of diagrams and graphics, is analyzed in detail in the text. Explanations of the illustrated patterns are also given and their application to the determination of the machined material mechanical properties of the used in the analytical model for the oblique cutting. These data are outlined in the manuscript text at the following locations: lines 504-508, 515-572, 579-582, 608-614, 665-687, 694-698. The authors have also added additional comments as recommended by the reviewer. These comments are marked in red font.

 

4. The authors should ensure that the conclusions drawn are directly supported by the results and avoid overgeneralizing or making claims not backed by the data. Please adjust to avoid possible misleading statements. The authors should expand the conclusion section to discuss the study's broader significance, its potential impact on the field, and any recommendations for future research or practical applications.

• The conclusion has been revised taking into account the reviewer's comments and suggestions. These changes are noted in red font.

 

5. The authors should consider revising the manuscript for clarity, ensuring that complex concepts are explained and that the language is accessible to a broader academic audience.

• The authors have again reviewed the manuscript for clarity of presentation and consistency of the terms and concepts used with the study field to which the reviewed manuscript belongs. The authors have made some adjustments to the used terms. All other without exception used terms and concepts are currently used in the theory and practice of cutting processes, mechanical engineering technology and numerical modeling of cutting processes accompanied by large plastic deformations and damage to the machined material with the chip formation. The proposed paper is intended for an audience consisting of engineers, researchers, and students engaged in the field of materials processing by cutting and, consequently, familiar with the relevant terminology and concepts.

Since the authors have been working in this knowledge field for quite a long time, it is quite possible that some terms and concepts, which are absolutely clear for the authors, present some difficulty for possible readers. In this regard, the authors kindly ask the respected reviewer to provide at least two examples of those terms and concepts that need to be further explained. Undoubtedly, the authors will try to analyze the text of the manuscript for similar terms and give all unclear parts of the text additional explanations.

 

6. The command of the English language is acceptable and minor changes should be done prior to publication

English level checked and some corrections have been performed as recommended by the reviewer.

Reviewer 3 Report

Please, see the file attached.

Comments for author File: Comments.pdf

Author Response

Answers to the comments of Reviewer #3:

The authors are very grateful to Reviewer #3 for meticulously reviewing and interpreting the content of the paper.

Reviewer #3:    This paper presents improved results for an analytical model of oblique cutting. The model enhancements take into account various factors, including the mechanical properties of the machined material, the thermomechanical conditions during the cutting process, significant changes in cutting parameters, and the inclination angle of the cutting tool's edge. To determine the mechanical properties of the material being machined, the Johnson-Cook constitutive equation is applied.

1. In summary, this paper focuses on refining the oblique cutting model by considering a more comprehensive set of factors, including material properties and thermomechanical aspects, and utilizes the Johnson-Cook equation to better represent the behavior of the machined material. This improved model may lead to more accurate predictions and insights into the cutting process. I am no sure that a model in J6C can be defined as analytical. Oxley, merchant and others were analytical ones.

• The authors do not define the Johnson-Cook constitutive equation as an analytical model. In the paper, it is proposed to improve the analytical model by identifying its initial data, such as the mechanical properties of the machined material, through a numerical cutting model that uses the Johnson-Cook constitutive equation. For an objective understanding of the developed methodology, the authors have adjusted the manuscript text and the flowchart for determining the mechanical properties of the machined material and transferring this data to the analytical cutting model algorithm (see Figure 4).

 

2. On the other hand, I checked the bibliography: Prediction of specific force coefficients from a FEM cutting model, The International Journal of Advanced Manufacturing Technology 43, 348-356 is not mentioned, when the main idea is to mix up model types. Neither is https://doi.org/10.1016/j.jmrt.2021.08.004 that proposed models for special inserts.

Yours is a numerical model.

• The paper proposed by the reviewer "Prediction of specific force coefficients from a FEM cutting model" is included in the reference list and analyzed as an example of the cutting process characterization (in this case, the determination of specific cutting coefficients) determined using a hybrid model (either directly by experimental studies of cutting forces or by numerical simulation of the cutting process).

As for the second recommended paper "Effects of laser-textured on rake face in turning PCD tools for Ti6Al4V", it is devoted to the experimental study of the laser-textured effects of PCD-coated cutting inserts in titanium alloy machining. The authors very much ask the respected reviewer to inform them about which models for special inserts the reviewer informs them about and which statements of the authors' proposed paper the reviewer's cited paper is related to.

 

3. Figure 4 and the flowchart is not well described: how much data is step 1?. Is this a correlation model because you have many data?

Or is it a J&C adjustment?

• The flowchart in figure 4 is corrected by specifying the input data in step 1. A cutting numerical model (in this case, oblique cutting) is used to determine the mechanical properties of the machined material. The flowchart shown in Figure 4 represents a principle algorithm for determining the mechanical properties of a machined material, which is described by a constitutive equation, in this example, the Johnson-Cook equation. The functioning of this algorithm is described in detail in Section 3.2.3. DOE sensitivity analysis, based on multiple numerical simulations of the cutting process through a finite element cutting model, is at the heart of this algorithm. As a result, the parameters of the constitutive equation that uniquely describe the material flow curve in the strain - strain-rate - temperature coordinates are determined. Simplistically, this can be defined as the adjustment of the constitutive equation for a given range of cutting modes.

 

4. Many points need a clear explanation, I kindly suggest. It is not clear the   main paper's purpose, the state of the art miss some works and conclusions would be better written as points.

• As recommended by the reviewer, the aim of the study has been added to section 2 (see lines 238-243); the literature list has been added and the source recommended by the reviewer has been analyzed; the main part of the conclusion is presented as separate items.

All changes carried out in the paper are marked in red font.

Round 2

Reviewer 3 Report

My comments were taken into account, accepted.