In-Process Fingerprints of Dissimilar Titanium Alloy Diffusion Bonded Layers from Hole Drilling Force Data
Round 1
Reviewer 1 Report
Its a new kind of approach, carrying out machining on a diffusion bonded stack assembly.
Additive manufacturing concepts are taken into consideration in this work.
Interesting.
1. scientific reasoning for the chosen composition, and the sequence used, and the layer width, thickness etc. should be provided
2. significance of blind layers should be adequately explained
Author Response
It is pleasing to hear that the manuscript has been accepted with minor corrections. The authors would like to thank the editor for their swift and efficient processing of the article and the reviewers for their insightful comments and suggestions. This document contains the response to the reviewer comments. Where corrections have been made to the manuscript, track changes has been used (within latex) and line numbers of said changes have been included within the responses.
Responses to Reviewer 1:
We are grateful to hear you found the article interesting, thank you for your feedback.
Comment 1: Scientific reasoning for the chosen composition, and the sequence used, and the layer width, thickness etc. should be provided.
Response: The alloys selected for study were chosen as they are all well established and also cover a range of alloys (in terms of alpha and beta phase content). This has been made explicit within the methodology section on line 130: “These alloys were selected as they are well established and have varying contributions of $\alpha$ and $\beta$ stabilising additions.” The sequences the stacks were made in were chosen to provide a wide range of bonds, and to examine similar bonds in different places within the stack. To address this in the text the text on line 148 has been added: “The order and type of alloys included in each stack were selected to provide a range of different bonds, at different points within each billet.” Layer width and thickness were of secondary importance to maintaining a consistent layer which was the priority and so the thickness varied for different alloy powders. Reference to the thickness of the layers is purposefully omitted for this reason.
Comment 2: Significance of blind layers should be adequately explained.
Response: On line 152 the authors explain the significance of the blind test methodology “This constituted a "blind" test, in order to demonstrate the effectiveness of force feedback analysis techniques for characterising the content of the titanium workpieces.”
Reviewer 2 Report
Excellent manuscript. Concise. Clear. Suggestions for improvement are as follows:
1. The abstract should be corrected. The first few sentences are not necessary. The abstract should contain answers to the following questions: What problem was studied and why is it important? What methods were used? What are the important results? What conclusions can be drawn from the results? What is the novelty of the work and where does it go beyond previous efforts in the literature? Please include specific and quantitative results in your abstract.
2. Titanium is not an adequate keyword. No innovations were made on titanium.
3. The last paragraph of the Introduction section should be corrected. First, list the shortcomings of previous research. Also, emphasize the scientific contribution of your research.
4. At the beginning of the Materials and Methods section, it would be desirable to present a flow diagram. It would be easier to follow the manuscript.
5. In section 2.1. FAST Sample Manufacture would do well to explain all selections. Why 60 mm? Why 14 mm? 1020â—¦C? 20 min? etc.
6. Similar to the previous one, why is the feed 0.131 mm/rev. Why is this value representative of your research? Why was a new tool used after two holes? Elaborate further.
7. What measurement system was used to generate the point cloud? What is the measurement uncertainty of that measurement system?
Author Response
It is pleasing to hear that the manuscript has been accepted with minor corrections. The authors would like to thank the editor for their swift and efficient processing of the article and the reviewers for their insightful comments and suggestions. This document contains the response to the reviewer comments. Where corrections have been made to the manuscript, track changes has been used (within latex) and line numbers of said changes have been included within the responses.
Responses to Reviewer 2
Thankyou for commenting on the clarity and quality of the manuscript.
Comment 1: The abstract should be corrected. The first few sentences are not necessary. The abstract should contain answers to the following questions: What problem was studied and why is it important? What methods were used? What are the important results? What conclusions can be drawn from the results? What is the novelty of the work and where does it go beyond previous efforts in the literature? Please include specific and quantitative results in your abstract.
Response: In the first few sentences the question of the problem and why it is important were answered, and therefore the authors have not removed them. The method, important results and conclusions are given in the abstract as it stands. The novelty of the work is given in the fact that “This is the first study where drilling 7 machinability of FAST diffusion bonded titanium alloys has been investigated”. In the context of this study quantitative results will not improve the quality of the abstract.
Comment 2: Titanium is not an adequate keyword. No innovations were made on titanium.
Response: Titanium has been removed as a keyword.
Comment 3: The last paragraph of the Introduction section should be corrected. First, list the shortcomings of previous research. Also, emphasize the scientific contribution of your research.
Response: The last paragraph now starts on line 125 and includes information about the scientific contribution of the research. As this is the first research where field assisted sintering technology (FAST) diffusion bonded samples have been drilled there are no shortcomings of previous research.
Comment 4: At the beginning of the Materials and Methods section, it would be desirable to present a flow diagram. It would be easier to follow the manuscript.
Response: The authors have previously considered adding a flowchart but decided against it as it was clear the chart did not add value to the manuscript and therefore will not be including a flowchart.
Comment 5: In section 2.1. FAST Sample Manufacture would do well to explain all selections. Why 60 mm? Why 14 mm? 1020â—¦C? 20 min? etc.
Response: The temperature, time and size of billets was based on previous work which is referenced within the introduction. These were selected as it is known that they were sufficient to fully consolidate the powder. In addition, 1020 â—¦C was identified to be above the beta transus temperature of all alloys.
Comment 6: Why is the feed 0.131 mm/rev. Why is this value representative of your research? Why was a new tool used after two holes? Elaborate further.
Response: 0.131 mm/rev was selected as it is the recommended industrial feed rate for the tools that were used. A new tool was used after every two holes to ensure no damage on the tools interfered with the results of holes drilled in other material stacks.
Information on the feed: “ (industry recommended cutting data for drilling Ti-64)” and number of holes: “to minimise the effect of tool wear on the results” has now been included on line 160 and 162 respectively.
Comment 7: What measurement system was used to generate the point cloud? What is the measurement uncertainty of that measurement system?
Response: The measurement system used for generating the point cloud is not measured but mathematically created based on the tool trailing edge position parametrisation from the input machining parameters (RPM, feed/rev). This trailing edge parametrisation creates a point cloud in 3D space with a point spacing in time equal to the acquisition rate of the dynamometer. This ensures that the data captured by the dynamometer can be accurately plot on top of this scaffold 'point cloud' to generate the force feedback plot. The uncertainty of this positional system is linked to the accuracy of the CNC feedback sensors to maintain a constant feed and RPM throughout the machining operation. In this case, the total CNC spindle power is much greater than the power required to perform this operation meaning that the parametrised point cloud is very accurate, as it can be seen on the fingerprint diagrams shown in this work.
Reviewer 3 Report
1. What was the unit of Nominal composition in Table 1? Was it wt.%? Should be added.
2. Please add (to Materials and Methods) the load applied to Vickers hardness measurements.
3. Line 326. Please add the bracket (shown in 2….
4. Can the authors somehow range the tested materials by their machinability based on the drilling test results? This could be added to the Discussion and Conclusions to better understand the effect of alloy chemistry on a bond’s machinability.
Author Response
It is pleasing to hear that the manuscript has been accepted with minor corrections. The authors would like to thank the editor for their swift and efficient processing of the article and the reviewers for their insightful comments and suggestions. This document contains the response to the reviewer comments. Where corrections have been made to the manuscript, track changes has been used (within latex) and line numbers of said changes have been included within the responses.
Responses to Reviewer 3
Thank you for the comments.
Comment 1: What was the unit of Nominal composition in Table 1? Was it wt.%? Should be added.
Response: Yes, wt.% has been added to table 1.
Comment 2: Please add (to Materials and Methods) the load applied to Vickers hardness measurements.
Response: The authors have added the load weight to the materials and methods section (1 Kg). Line 178 now reads: “ … DuraScan 80 G5 with a load weight of 1 Kg.”
Comment 3: Line 326. Please add the bracket (shown in 2….
Response: Added missing bracket to line 326 now line 330.
Comment 4: Can the authors somehow range the tested materials by their machinability based on the drilling test results? This could be added to the Discussion and Conclusions to better understand the effect of alloy chemistry on a bond’s machinability.
Response: In this study the order in which any two alloys were drilled determined the machinability characteristics that were exhibited; therefore, it would be misleading and inaccurate to try and suggest a machinability hierarchy for the tested alloys.
