The Effect of Optimised Combined Turning and Diamond Burnishing Processes on the Roughness Parameters of CuZn39Pb3 Alloys
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript presents a valuable investigation into the optimization of combined turning and diamond burnishing processes for CuZn39Pb3 brass alloy, with a focus on sustainable manufacturing. The topic is relevant, and the study aims to address a knowledge gap regarding surface integrity improvements for this material. The comparison of flood lubrication, dry, and dry+cool-assisted conditions is particularly pertinent.
However, the manuscript in its current form suffers from significant methodological shortcomings in the experimental design and statistical analysis, which undermine the validity and robustness of the reported findings. Major revisions are required to address these concerns before the manuscript can be considered for publication.
Major Concerns:
1. Experimental Design and Lack of Replication:
The description of the experimental design is unclear. While the authors mention "planned experiments" and the use of a "Box-Wilson design," the specific type of design (e.g., Central Composite Design, Box-Behnken) is not explicitly stated for the DB optimization phase. More critically, there is no mention of replication in any of the experimental runs (Tables 2 and 4). The absence of replicates makes it impossible to estimate pure error, which is a fundamental requirement for a meaningful Analysis of Variance (ANOVA) and for assessing the lack-of-fit of the regression models. This omission severely weakens the statistical conclusions.
2. Incomplete Reporting of ANOVA:
The manuscript references ANOVA results and presents main effects plots (Figures 3 and 7), but it fails to provide the complete ANOVA tables. Essential statistical data such as degrees of freedom, sum of squares, mean squares, F-values, and p-values are missing. For the scientific community to evaluate the significance of the factors and the adequacy of the models, this information is indispensable. The current presentation is insufficient for peer verification.
3. Questionable Statistical Significance and Model Robustness:
The authors' claim of multiple significant factors is brought into question. An independent analysis of the presented data using established RSM software (Design-Expert) indicated that only one factor was statistically significant for the models. This stark discrepancy suggests that the models presented in the manuscript may not be robust or statistically sound. The factors deemed "significant" by the authors may be artifacts of an analysis that does not properly account for experimental error due to the lack of replication.
4. Suboptimal Structuring of the Investigation:
The decision to optimize the turning and diamond burnishing processes sequentially, and to treat the three turning environments (F, D, D+C) as entirely separate entities for the DB study, is a major limitation. A more powerful and efficient approach would have been to incorporate the "turning process" as a categorical factor within a single, unified experimental design for the DB phase. This would have allowed for a direct and statistically rigorous comparison of the three conditions and the investigation of their interactions with other DB parameters (e.g., force, feed rate), providing much deeper insight.
In conclusion, the manuscript requires a substantial revision to address the statistical and methodological flaws. The authors are strongly encouraged to:
1. Clearly define the type of experimental design used for both the turning and DB optimization.
2. Repeat the experimental work to include at least three replicates for each experimental run to allow for a proper estimation of error.
3. Perform and report complete ANOVA tables for all models, including F-values and p-values.
4. Re-evaluate the significance of the factors and the model adequacy based on the replicated data.
5. Consider re-analyzing the entire system with a more integrated design that includes the turning condition as a categorical factor, if feasible.
Once these fundamental issues are resolved, the manuscript will be significantly strengthened and will make a more reliable contribution to the field.
Author Response
Please see the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe primary concern is that the study limits itself almost exclusively to surface roughness (Ra, Rq, Rsk, Rku), without linking these metrics to functional performance, mechanical behavior, or surface integrity measurements (hardness, residual stress, and microstructure). However, the authors addressed these concerns in the discussion and conclusion sections, indicating that this will be addressed in future studies.
Please address the items below:
1. For the statistical analyses (ANOVA, regressions, optimal parameters), please provide the key statistical information (p-values, F-tests, R², adjusted R², residual analysis, etc.).
2. There is no report of measurement uncertainty, repeatability, or instrument calibration, although the SJ-210 roughness tester and the hardness and tensile machines have known uncertainty ranges. Please report uncertainty of Ra measurements, standard deviation bars on plots, and confidence intervals for optimized Ra predictions.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis study investigates the effects of different surface cold-working methods, particularly diamond burnishing (DB), on the surface integrity (SI) of CuZn39Pb3 leaded brass alloys. The paper evaluates the influence of various burnishing conditions (flood lubrication, dry, and dry with cool assistance) on surface roughness parameters. The experimental design is comprehensive, with the study offering valuable insights into optimizing DB processes to improve surface quality while exploring sustainable alternatives to conventional cutting fluids. The results indicate that both dry and cool-assisted burnishing processes can achieve comparable roughness values to traditional flood-lubricated burnishing, presenting a sustainable approach to manufacturing. However, the manuscript requires significant improvements in clarity, data presentation, and the discussion of some aspects, particularly the environmental implications of each method and the relationship between surface characteristics and component performance. Furthermore, the paper would benefit from more detailed analysis and a broader discussion of the materials and methods involved.
- The experimental setup and methodology are presented clearly, but the paper would benefit from a more detailed explanation of the environmental and health implications of cutting fluids, particularly how the proposed dry and cool-assisted processes compare to the flood-lubricated process in terms of overall sustainability. A more in-depth discussion on the potential reduction in cutting fluid usage, energy savings, and waste management would enhance the relevance of the study in an industrial context.
- The data analysis in Section 3 could be strengthened by providing more context around the statistical significance of the results. While ANOVA is mentioned, the inclusion of confidence intervals or p-values for each factor's influence on Ra would provide greater clarity and support the robustness of the conclusions.
- The roughness parameters, especially skewness and kurtosis, are crucial for evaluating wear resistance, yet the manuscript could benefit from a more explicit connection between these parameters and the mechanical performance of the machined parts. Specifically, how do these surface features translate into performance in real-world applications, such as wear resistance or fatigue strength? Further elaboration on the tribological testing would strengthen the claims.
- While the regression models presented in Table 5 are informative, the discussion of the coefficients and their practical implications is somewhat lacking. For instance, while the influence of burnishing force and diamond radius is well-established, a deeper exploration into the physical significance of these interactions would be valuable, especially in relation to the alloy's microstructure and hardness.
- The manuscript could improve its readability by reorganizing the results and discussion sections to avoid excessive repetition of points. For example, some of the information about roughness values (Ra, Rq, etc.) is mentioned multiple times without adding new insights. A more structured approach to discussing these results would improve the clarity of the manuscript.
- The conclusions mention that the DB D-process achieved the greatest reduction in Ra, but the manuscript does not explore why this process is more effective in detail. A more thorough discussion on the heat generation and softening effect during dry burnishing would clarify this result. Also, it would be useful to compare these findings with other similar studies in the field to highlight how this work contributes to the existing body of knowledge.
- Some of the figures, particularly Figures 11 to 14, display roughness profiles and experimental data. It would be helpful to include more information on the resolution and precision of the surface roughness measurements, as well as a clearer visual distinction between the various burnishing processes. This will help readers better interpret the data and appreciate the nuances of each process.
- The reference list appears to be comprehensive, but there are some areas where it could be expanded. The article "Recent Advances in Design and Preparation of Micro Diamond Cutting Tools" introduces the current research status of diamond tools. The author should draw on the content therein to enrich the introduction part. For instance, key studies on the environmental and health risks of cutting fluids, as well as the broader impact of dry and cool-assisted burnishing, are not sufficiently represented. Including additional references on the effects of surface integrity on the fatigue and wear resistance of CuZn39Pb3 alloys would enhance the depth of the review.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThis manuscript presents an experimental work on the effect of cooling and burnishing conditions on the surface quality of copper alloy. This work is comprehensive and well-written, thus it can be considered for publication after some modifications are carried out.
The authors could provide a reference for the workpiece material properties.
The authors should provide a schematic for the machining setup and the different devices used.
Given the number of different investigations carried out in this work it is essential that the authors provide an appropriate flowchart to clarify which experiments were carried out and which parameters were varied in each experiment, as well as which investigations were based on regression models.
Regarding the considerable improvement of surface roughness with a burnishing tool of 4 mm radius, the authors could provide a more detailed explanation, perhaps with an appopriate schematic to indicate the reasons for this result, especially when the roughness increases so much for a radius of 5 mm.
If possible, the authors could comment on the level of residual stresses occuring in the workpiece in specific cases e.g. by a FE model or measurement in order to correlate them with the obtained results.
Author Response
Please see the attached file
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have thoroughly and thoughtfully addressed all points raised in the initial review. Their revisions and clarifications, particularly regarding the experimental methodology and statistical analysis, have significantly strengthened the manuscript's rigor and clarity. The responses demonstrate a serious engagement with the peer review process.
The revised manuscript, "The effect of optimised combined turning and diamond burnishing processes on the roughness parameters of CuZn39Pb3 alloys," represents a high-quality, complete, and publishable piece of research. The authors have successfully remedied all prior concerns. The study makes a valuable contribution by demonstrating the feasibility and effectiveness of optimized, sustainable diamond burnishing processes for enhancing the surface integrity of a critical engineering alloy. I recommend its acceptance without further modification.
Reviewer 3 Report
Comments and Suggestions for AuthorsIt can be accepted in present version.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors carried out most of the required modifications in their manuscript. Thus it can be now accepted for publication.
