Investigation of Situational Correlations of Wire Electrical Discharge Machining of Superhard Materials with Acoustic Emission Characteristics
, Mikhail P. Kozochkin, Artur N. Porvatov, Alexander P. Malakhinsky and Yury A. Melnik *
Round 1
Reviewer 1 Report
Title of the manuscript: Investigation of situational correlations of electrical discharge
machining of superhard materials with acoustic emission characteristics
The manuscript reports a correlational analysis on acoustic assisted EDM of hard material. Some major concerns associated with this study are listed below.
1. The abstract of the manuscript is very confusing. It need to contain some significant results from the studies and not just introduction. Moreover, the abstract should be a generalized description of the manuscript which can give the reader a primary idea of the work without disclosing too many details unnecessarily. The authors should try to avoid symbolic representation in the abstract and explain through words as much as possible.
2. Why is the research gap mentioned in the abstract? It should be presented just after literature review before the methodology.
3. Keywords are not appropriately presented. Must begin with words and not short forms.
4. The literature review is too obsolete. Papers are cited from 1980-2015. The authors are advised to cite new literature from last five years as such research gap is established properly.
5. The work looks more of literature review than an experimental wor. The authors are advised to make the literature bit oncise, compact, and remove unnecessary references.
6. Research gap is not clear. In short what is the novelty?
7. The objectives doesn’t look satisfactory as well.
8. What type of power supply was used in the experimental setup?
9. What kind of pulse were generated in the pulse generator?
10. What type of laser source was used in the study?
11. Figure 3 needs proper representation of parts.
12. A proper details of work piece and tool must be included in the study.
13. What do the authors mean by superhard materials? How is the hardness assessed in the present context of study?
Author Response
Dear reviewer,
We agree with all your proposals and comments and have modified the manuscript accordingly.
We hope the manuscript will be suitable for publishing in Metals and attract many potential journal readers with your comments.
Kind regards,
Authors.
Point 1: The abstract of the manuscript is very confusing. It need to contain some significant results from the studies and not just introduction. Moreover, the abstract should be a generalized description of the manuscript which can give the reader a primary idea of the work without disclosing too many details unnecessarily. The authors should try to avoid symbolic representation in the abstract and explain through words as much as possible.
Response 1: The abstract has been revised. Symbolic representations have been removed. The reader is given a primary idea of the objectives of the research and the content of the article.
Point 2: Why is the research gap mentioned in the abstract? It should be presented just after literature review before the methodology.
Response 2: The abstract has been rewritten, and there is no mention of research gaps. However, it can be noted that the number of publications devoted to the study of acoustic emission during erosion processing is two orders of magnitude less compared to studies in the field of blade processing.
Point 3: Keywords are not appropriately presented. Must begin with words and not short forms.
Response 3: The short form has been replaced by the expanded name of the technology.
Point 4: The literature review is too obsolete. Papers are cited from 1980-2015. The authors are advised to cite new literature from last five years as such research gap is established properly.
Response 4: The article left only 4 sources dated before 2000. Most sources after 2018 have links to articles from 2023. It should be noted that the best publications that describe the study of physical processes that accompany the processing of metals belong to the last century. It was then that the foundation was laid in the mechanics of blade machining, the main contribution was made to the theory of electroerosive machining.
Point 5: The work looks more of literature review than an experimental work. The authors are advised to make the literature bit oncise, compact, and remove unnecessary references.
Response 5: From page 3 to the very end, the paper presents the experimental results obtained by the authors in the course of research conducted in recent years. References to earlier work are provided to support the assumptions and conclusions made.
Point 6: Research gap is not clear. In short what is the novelty?
Response 6: At present, EDM machines are controlled based on the monitoring of electrical parameters. Practice shows that such control cannot always provide timely information on an increase in the concentration of erosion products in the electrical gap. This leads to breaks in the wire electrode, to work with a pulse utilization factor in the range of 0.2-0.4 instead of the rational range of 0.6-0.8, to frequent short circuits, lower productivity and quality of the resulting surface. To improve the performance and reliability of the processing process, the relationship between the parameters of acoustic emission signals and the most important EDM characteristics is investigated in this work. There are very few publications in this direction. The relationships presented in the article between the parameters of acoustic emission signals and the state of the EDM process (productivity, efficiency, change in the concentration of erosion products) are a scientific novelty of practical importance.
Point 7: The objectives doesn’t look satisfactory as well.
Response 7: The objectives of the research are specified in the abstract.
Point 8: What type of power supply was used in the experimental setup?
Response 8: The research was carried out on a CUT30 model cutting machine, where an independent generator was used. Such a generator delivers pulses to the processing zone, regardless of the state of the interelectrode gap.
Point 9: What kind of pulse were generated in the pulse generator?
Response 9: The figure shows the idealized forms of voltage and discharge current pulses.
Point 10: What type of laser source was used in the study?
Response 10: The experiments were carried out using a diode-pumped pulsed solid-state laser engraver, model U-15, RMI Laser LLC, USA. Wavelength 808 nm.
Point 11: Figure 3 needs proper representation of parts.
Response 11: Figure 3 shows a stand with a laser described in paragraph 10. A workpiece in the form of a steel plate (0.08% C) is located on the table. With the help of a magnet, an accelerometer is attached to the plate, with the help of which the signals described in the article were obtained.
Point 12: A proper details of work piece and tool must be included in the study.
Response 12: Section 2.1 describes the composition of the electrode-tool and the electrode-workpiece, the diameter of the wire is indicated. The blanks were of a simple form: rods with a section of 10x15 mm.
Point 13: What do the authors mean by superhard materials? How is the hardness assessed in the present context of study?
Response 13: The hardness of the tool alloys that were used in the experiments are presented in Table 2. On the Rockwell A scale, they are at least 90 and 91 units.
Reviewer 2 Report
I recommend adding:
1. Samples before and after cutting from both materials
2. Some parameters were investigated on the samples to take into account the changes of the EDM process
3. On the basis of which the bands for vibrations were determined from the frequency records in figures 7-16. Under the defined conditions, the values ​​are repeated.
4. With what repeatability the measurements were made.
Author Response
Dear reviewer,
We agree with all your proposals and comments and have modified the manuscript accordingly.
We hope the manuscript will be suitable for publishing in Metals and attract many potential journal readers with your comments.
Kind regards,
Authors.
Reviewer 2:
I recommend adding:
Point 1: Samples before and after cutting from both materials
Response 1: Surface quality after EDM is a big and complex topic. The appearance of the surface before EDM is determined by the technology for obtaining the workpiece and may not have a direct relation to the quality of the surface after the cutting operation. Figure 18 shows a photograph of the trace from the tool-electrode after its breakage; the profilogram of the trace is also shown there. This is related to the topic of the article, which considers the possibility of preventing wire electrode breaks by acoustic emission signals.
Research is currently underway on the effect of EDM modes on surface quality. Based on the results, perhaps several articles will be written, where not only roughness or hardness will be considered, but also the state of the crystal lattice in the vicinity of characteristic traces on the cut surface.
As an example, the figure below shows the surface view of a superalloy workpiece after EDM. There are various hypotheses explaining the formation of such a pattern. It is important to understand what happened to the surface layer in the vicinity of these traces.
View of the surface of a heat-resistant alloy after cutting off on an WEDM machine.
Point 2: Some parameters were investigated on the samples to take into account the changes of the EDM process.
Response 2: In Section 1, it was said that studies of the relationship between processing conditions and the characteristics of the resulting surfaces are currently underway. This is a topic for future posts.
Point 3: On the basis of which the bands for vibrations were determined from the frequency records in figures 7-16. Under the defined conditions, the values ​​are repeated.
Response 3: The frequency ranges for determining the changes in the transmission coefficients were determined on the basis of a preliminary spectral analysis of the signals. The shape of the spectrum of acoustic emission signals depends on the natural frequencies of the elastic system of the machine: workpiece, fixture, work table. Eigenfrequencies under constant workpiece mounting conditions are quite stable, but the oscillation amplitude at these frequencies changes depending on the change in processing conditions. Therefore, those frequency ranges are selected where the oscillation amplitudes stand out well against the background of noise, and where changes in processing conditions cause the most noticeable changes in amplitude. Relevant explanations have been added to the article.
Point 4: With what repeatability the measurements were made.
Response 4: With the hard alloys described in the article, a series of 20 experiments was carried out. The nature of the change in the parameters of acoustic emission signals as the concentration of erosion products in the interelectrode gap increased stably. Similar studies were also carried out with cermets (Al2O3 + TiC), where a decrease in the transmission coefficients at high frequencies was also observed with an increase in the concentration of erosion products. An appropriate addition has been made to the text of the article.
Reviewer 3 Report
This manuscript presents a methodology for monitoring wire breakage during WEDM, mainly by acoustic signals. This work is rather interesting, it is well-written, the methodology is clear and detailed and the validation of the proposed methodology is appropriate. Thus, it can be recommended for publication, after some mandatory modifications are performed to the manuscript.
In the title and the whole manuscript, the authors should directly mention that the research is relevant to Wire-EDM, not generally EDM.
In the Abstract and Introduction section, the authors should present more details regarding the quantities of EDM, which are correlated to the AE signals.
In Section 2.1, the authors should mention the thermal and electrical properties of the two materials. Moreover, the values of every parameter of the WEDM process, which was used for the experiments should be mentioned and displayed in an appropriate table.
The authors should further justify their choice, regarding the placement of AE sensors and the use of the pulsed laser system for the verification of their methodology.
Although the results indicate that the proposed methodology is valid and appropriate for the prediction of wire breakage, the authors could have demonstrated the capabilities of their methodology for at least two additional cases, with different WEDM parameters values.
Author Response
Dear reviewer,
We agree with all your proposals and comments and have modified the manuscript accordingly.
We hope the manuscript will be suitable for publishing in Metals and attract many potential journal readers with your comments.
Kind regards,
Authors.
This manuscript presents a methodology for monitoring wire breakage during WEDM, mainly by acoustic signals. This work is rather interesting, it is well-written, the methodology is clear and detailed and the validation of the proposed methodology is appropriate. Thus, it can be recommended for publication, after some mandatory modifications are performed to the manuscript.
Point 1: In the title and the whole manuscript, the authors should directly mention that the research is relevant to Wire-EDM, not generally EDM.
Response 1: Changes have been made to the title and text.
Point 2: In the Abstract and Introduction section, the authors should present more details regarding the quantities of EDM, which are correlated to the AE signals.
Response 2: This information has been added to the Conclusions section.
Point 3: In Section 2.1, the authors should mention the thermal and electrical properties of the two materials. Moreover, the values of every parameter of the WEDM process, which was used for the experiments should be mentioned and displayed in an appropriate table.
Response 3: Information added to Section 2.1.
Point 4: The authors should further justify their choice, regarding the placement of AE sensors and the use of the pulsed laser system for the verification of their methodology.
Response 4: Laser technologies and WEDM belong to the group of technologies that process concentrated energy flows. This determines the commonality of the relationships between the characteristics of these technological processes and the parameters of acoustic emission signals. This article contains a link [29] to an earlier article by the authors devoted to this issue.
Point 5: Although the results indicate that the proposed methodology is valid and appropriate for the prediction of wire breakage, the authors could have demonstrated the capabilities of their methodology for at least two additional cases, with different WEDM parameters values.
Response 5: Work in this direction continues. The possibilities of acoustic emission signals when working on a piercing machine were investigated. Experiments are currently underway with WEDM superalloy. The results will certainly be published.
Round 2
Reviewer 3 Report
The authors have performed most of the required modifications to their manuscript. Thus, it is recommended for publication.
