Effect of Build Parameters on the Compressive Behavior of Additive Manufactured CoCrMo Lattice Parts Based on Experimental Design

Round 1

Reviewer 1 Report

 

Review for metals-1754635

Title: Effect of Build Parameters on the Compressive Behavior of Additive Manufactured CoCrMo Lattice Parts Based on Experimental Design

Comments to Authors

1.  In abstract, the significance of compressive strength of Additive Manufactured CoCrMo Lattice Parts with specific applications need to be highlightened.

2.   Are there are only three parameters (build orientation, volume fraction and lattice type) that affect the quality of DMLM parts.  How these three parameters and levels of variables are chosen. This needs to be clearly explained.

3.    Although there are other design of experiments available such as central composite design, Box-Behnken design and Full factorial designs, reason for selecting Taguchi method need to be clearly explained.

4.     Abstract need to be revised incorporating the numerical values of obtained results.

5.   Authors need to clearly abbreviate when they appear first in the manuscript. For example, IWP, FRD, OCTO and so on.

6.     Name the component presented in Figure 2.

7.     How many replicates considered for each experimental trial and present the average error in terms of ± average values.

8.     The reason for negligible influence of build orientation need to be better explained with respect to Fig. 6, 7 and 8.

9.     The optimal conditions for specific energy consumption, elastic modulus, and yield strength.

10.  The optimal conditions and their trends are found different for all three outputs and the common single optimal conditions for all outputs require solving with multiobjective optimization techniques such as grey relational analysis, super ranking concept, TOPSIS, MOORA, DEAR, and so on. Please select any one of the above following techniques.  

 

You can find the below references to be useful (not mandatory to cite in your articles).

 

1.     Optimization of abrasive water jet machining for green composites using multi-variant hybrid techniques. In Optimization of manufacturing processes (pp. 129-162). Springer, Cham.

 

2.     Multi response optimization of green sand moulding parameters using Taguchi-DEAR method. In Applied Mechanics and Materials (Vol. 895, pp. 1-7). Trans Tech Publications Ltd.

 

3.     Performance analysis of cow dung as an eco-friendly additive material for sustainable moulding and casting. China Foundry, 16(6), 423-429.

 

4.     Sustainable machining: Modelling and optimization using Taguchi, MOORA and DEAR methods. Materials Today: Proceedings, 46, 8941-8947.

 

5.     Experimental analysis and optimization of EDM parameters on HcHcr steel in Context with different electrodes and dielectric fluids using hybrid Taguchi-based PCA-utility and Critic-utility approaches. Metals, 11(3), 419.

 

6.     Experimental investigation of selective laser melting parameters for higher surface quality and microhardness properties: taguchi and super ranking concept approaches. journal of materials research and technology, 14, 2586-2600.

 

 

 

Author Response

Thank you for your feedbacks and comments. Please find the responses at the attached document.

Author Response File: Author Response.pdf

Reviewer 2 Report

1 Abstract: “direct metal laser melted (DMLM)” is suggested to be replaced by “ laser powder bed fusion (LPBF) manufactured”

 

2 Line 97:” gyroid, iwp” should be “Gyroid, IWP”

 

3 Some details of powders for LPBF manufacturing should be provided, including the preparation method, and average size.

 

4 How to calculate the energy absorption? The procedure should be provided.

 

5 The authors just present some simple results. This manuscript looks like an experimental report rather than an academic article. The authors are suggested to interpret the experimental results in more details, such as, why 0.4 volume fraction, 45 degree build orientation with diamond structure was found to be the best parameter set for σy? why 0.4 volume fraction, 60 degree build orientation with Gyroid structure was the best parameter set for E? and why Diamond structure with 0.4 volume fraction and 60 degree build orientation showed the highest specific 370 energy absorption?

Author Response

Thank you for your feedbacks and comments. Please find the responses at the attached document.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript entitled “Effect of build parameters on the compressive behavior of additive manufactured CoCrMo lattice parts based on experimental design” presents an effort to analyze the effects of volume fraction, lattice type, and build orientation of CoCrMo lattice structures produced by direct metal laser melting on their yield strength, elastic modulus, and specific energy absorption. For this purpose, the authors printed a number of samples designed using the Taguchi approach and analyzed the experimental characterization results under compression using ANOVA.

The subject matter is timely and of potential interest to readers of Metals. The Introduction gives an idea of the research novelty (which is mainly the material of a lattice structure). Still, it does not provide a reader with an idea of the research topicality, the clear reason why the research was carried out, and how the community could use the results. Research limitations are not highlighted. In my opinion, the major flaw in methodology is the absence of process parameters indication (see my comments below). Another major flaw is drawing a conclusion that is contradicted by the authors’ results (see my comments below). A minor grammar check is necessary.

I recommend that this paper not be accepted without major revision.

 

The following deficiencies should be addressed as well:

 

Introduction

(i)              Please refer to the original articles of Schoen, Fischer and Koch, and Gozdz and Holyst in lns. 40-44, p. 1.

(ii)            It might be helpful for a reader if you clarified the difference between two terms ‘Direct Metal Laser Melting Laser’ and ‘Laser Powder Bed Fusion’ or clearly stated that they are synonyms (p. 2, lns. 47-48).

(iii)          I would recommend further editing of the Introduction for better readability. In my opinion, a mere listing up of ‘who did what’ with poor generalization does not bring much to a reader. In my opinion, the current introduction does not summarize research related to the topic. You also try to contrast, but, in some cases, it is unclear where the contrast comes from (e.g., lns. 80-81, p. 2).

(iv)           I would also suggest briefly discussing the effects of a microstructure as the latter links process parameters and build orientation with the mechanical properties. For instance,

a.      Effect of processing parameters and strut dimensions on the microstructures and hardness of stainless steel 316L lattice-emulating structures made by powder bed fusion. Additive Manufacturing, 2021, 40, 101943.

b.     Effects of scanning pattern on the grain structure and elastic properties of additively manufactured 316L austenitic stainless steel. Materials Science and Engineering: A, 2022, 832, 142447.

c.     A mechanical comparison of alpha and beta phase biomedical TiTa lattice structures. Materials & Design, 2021, 212, 110220.

(v)             Earlier (p. 1, lns. 36-38), you have mentioned three categories of lattice structures. It might be helpful for a reader if you explained which category a body centered cubic type lattice structure belongs to (p. 2, lns. 56-58).

(vi)           Please indicate the materials of lattice structures in all cases reviewed in the Introduction to provide a reader with a broader view (p. 2, lns. 55-79).

(vii)         It might be interesting to discuss why the results reported in the literature on the effects of a lattice structure type on the mechanical properties might be contradictory (e.g., lns. 61-62 and 74-76, p. 2).

(viii)       Was the 90° loading direction relative to the build direction meant in ln. 112, p. 2?

 

Materials and Methods

(ix)           Please clarify how the parameter combinations were set in Table 2 (p. 4, ln. 166). For example, why is it ‘2 1 2’ for the fourth specimen and not ‘2 2 2’?

(x)             The notation clarification you use after equations should not start a new paragraph; it is even not the beginning of a sentence (p. 4, ln. 179; p. 7, ln. 252). Please correct.

(xi)           Please indicate the process parameters used to produce samples, including power, scanning speed, scanning strategy, hatch distance (Section 2.2).

(xii)         Please add the powder recoater direction to Fig. 1.

 

Results and Discussions

(xiii)       Please discuss in more detail how your results are consistent with those reported in [14], ln. 229, p. 6.

(xiv)       According to Table 4, the conclusion drawn in lns. 229-231, p. 6, and later stated in Conclusions (lns. 364-366, p. 12) is not true. According to Tables 1 and 2, samples of the diamond lattice type are 2, 4, and 9 ones. You addressed the exception for 0.2 volume fraction, but for 0.3 volume fraction the gyroid samples outperformed the diamond ones in E, and for 0.4 volume fraction the gyroid samples outperformed the diamond ones in terms of both s_y and E. Please discuss your results in more detail.

(xv)         Please indicate the dispersion in Table 4.

(xvi)       Please clarify how you define a more uniform deformation for gyroid and diamond samples with the increase in volume fraction (lns. 256-258, 273-275, p. 7).

(xvii)     It might be interesting to discuss what a rapid stress increase in the densification stage is related to (lns. 271-272, 281-282, 287-288, pp. 7 and 8).

(xviii)    Please explain the notations of parameters in Table 5.

(xix)       In my opinion, you should not introduce ‘ref’ in ln. 323, p. 10, you do not use it anywhere else and usually a reference number in square brackets is enough.

(xx)         Please clarify what is meant by ‘strut orientation’ in ln. 331, p. 10, and provide more detail.

Author Response

Thank you for your feedbacks and comments. Please find the responses at the attached document.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Congratulations, for successful incorporation of all comments in your revised manuscript. 

Author Response

Thank you for your valuable suggestions

Reviewer 2 Report

The authors have revised this manuscript according to the comments. I have no further comment and suggest to accept it for publication. 

Author Response

Thank you for your valuable suggestions

Reviewer 3 Report

The revised version is better than the original manuscript; however, it still requires major revision before the paper is accepted. Unfortunately, for some reason, the authors choose to ignore a part of my previous comments.

 

Language

General: the grammar check I wrote about in my previous comments is still necessary. The text contains multiple grammar issues (e.g., ‘structures shows’, ln. 69, p. 2; ‘strut-base type’, ln. 70, p. 2; ‘in different loading direction’, ln. 140, p. 3), repetitions (e.g., ‘mechanical properties of different types of lattice structures. The mechanical properties of different types of lattice structures’, lns. 65-67, p. 2; ‘Primitive structure showed that Primitive structure showed’, lns. 111-112, p. 3), unclear statements (‘metal powders are coated with an amount of pre-defined thickness’, ln. 59, p. 2), etc. Please note that these are just some examples; the text contains more issues.

 

Introduction

(i)              General: the section does not provide a reader with an idea of the research topicality, the clear reason why the research was carried out, your study hypothesis, and how the community could potentially use the results or benefit from them. The latter could be stated in Conclusions and/or Abstract

(ii)            Unfortunately, the Introduction structure has not changed in the revised version. It is still a mere listing of ‘who did what’ with poor generalization, which does not bring much to a reader. What should the reader get out of, e.g., lns. 65-124? Please try to generalize and categorize the content (e.g., by the lattice type, mechanical property or material), compare and contrast, and describe trends rather than simply list.

(iii)          In the answer to a reviewer, you refused to discuss the microstructure effects, aiming to shorten the Introduction (which I, by the way, have not asked about in contrast to your statement). However, for some reason, you still discuss different categories of materials (plastics, ceramics, metallic materials) and various manufacturing methods (laser powder bed fusion, selective laser sintering, stereolithography, fused deposition modeling). Could you please clarify how this is related to your research?

(iv)           It is unclear where the x direction is (ln. 135, p. 3).

(v)             Loading and build directions are related; please discuss them in the integrated context (lns. 125-153, pp. 3 and 4).

(vi)           It might help the reader if you mentioned specific geometric parameters (ln. 168, p. 3).

(vii)         You write about a ‘limited number of researches focused on mechanical properties of lattice structures produced by LPBF from CoCrMo’ (lns. 172-173, p. 3) but do not discuss any of them in the Introduction.

 

Materials and Methods

(viii)       It might help the reader if you introduced an appropriate reference in lns. 200-20, p. 4.

(ix)           I would suggest moving lns. 252-257, p. 7, as they clarify your choice of the material.

 

Results and Discussions

(x)             Please clarify what you consider as a specific energy absorption in the paper by Castro et al. [17].

(xi)           According to Castro et al. [17], diamond samples did not show the highest yield strength for all volume fractions considered (lns. 285-287, p. 8), only for the volume fraction of 0.4, which is opposite in your case.

(xii)         In lns. 310-312, you use two different notations for the yield strength of a lattice part.

(xiii)         Your study is rather descriptive, without regard to any causal or other hypothesis. Please introduce a discussion. You might think of comparing your research with the literature, discuss the possible reasons of your findings, etc.

 

Conclusions

(xiv)       Research limitations are not highlighted.

 

Author Response

Thank you very much for all the suggestions. Based on your suggestions, we revised the study. Please find the response at the attachment.

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

The revised version is better than the original manuscript; however, it still requires minor revision before the paper is accepted. 

 

1. 1. General: the grammar check I wrote about in my previous comments is still necessary. The text contains multiple grammar issues (e.g., ‘the microstructure development is more complicated which affect’, lns. 153-154, p. 4; ‘correlation were shown’, lns. 164-165, p. 4; ‘parameters affects’, lns. 198-199, p. 4; ‘in different application’, ln. 204, p. 4), incomplete sentences (e.g., ‘find the optimum process parameters on mechanical properties’, lns. 166-167, p. 4), unclear statements (‘powders are laid with an amount’, lns. 57-58, p. 2), etc. Please note that these are just some examples; the text contains more issues. 

2. 2. Abstract: you did not mention the exception related to Gyroid samples (lns. 23-25, p. 1) 

3. 3. I would argue that [25] is a good example of fine grains at the bottom as compared to the top of a build, as they state that the ‘average equivalent grain diameter is larger at the bottom of the vertical section (65 µm) than at the middle (56 µm) which is close to the top (55 µm)’. 

4. 4. When formulating the knowledge gap, you contradict yourself: please compare lns. 156-158 and 170-172, p. 4. 

5. 5. All notations should be explained (ln. 239, p. 6) 

 

Author Response

We thank the referee for his/her insightful comments. Please find the attached file for our point-by-point responses:

Author Response File: Author Response.pdf