Studies on the Numerical Control Programming for Multi-Axis Machining of Turbomolecular Pump Rotor
Round 1
Reviewer 1 Report
Some comments, ideas and remarks in the attached file.
The research presented in the work has a certain practical utility, the results are good and well presented.
Probably, the paper does not fit best in the Electronics journal, but in another one, with topics in mechanical engineering, manufacturing, assembly.
Some block of text are too large, please break them in several smaller blocks, they will be easier to read.
Several check steps could be added after scanning and after simulation of tool paths (in the logical diagram).
Some info about the milling tools are maybe important to be mentioned here: type, producer, size etc.
Add a few sentences about how to balance the entire rotor, assembly conditions and how everything is checked in real conditions, not on the 3D model.
Are there any tests conducted with the rotor ?
The list of bibliographic papers could be completed by some newer papers/books/patents/PhD Theses etc.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
General comment
Although the main direction is towards the Electronics domain, the information and aspects presented could be more useful toward another journal (Processes, Micromachines, Materials).
Reviewer’s observation is presented in the following paragraphs.
Abstract
What is the state of the AL6061? T1, T2…. etc.
If the Al6061 alloy mentioned is referring to the raw material from which the machining has been made, please state this. Please rephrase.
Add a phrase stating the most important findings of the work performed.
Introduction
Add a reference to the first phrase of Paragraph 1. Also, please make sure all the references are well placed within the main text. Paragraph 2 has no reference although the information seems to be from a reference.
Paragraph 66. Mention what geometrical error were taken into consideration in [11] and what they have obtain at the end.
Paragraph 75. Computer-aided design acronym first appears in Abstract. Add the acronyms in their order of appearance.
There are only 3 bibliographic studies presented in the Introduction that are relevant and related to the work performed by the Authors. Please add more relevant information on this.
State clearer the novelty of the paper and what does it bring to the scientific community. So far, the objective presented mentions only a reverse engineering process of an existing part. Also, there is no mentioning of why the authors want to perform this study and what they expect from this. If the efficiency (performance, process and/or methods) is one of the expectations, mention the percentage (or other) of such expectations, and to what it will be compared to, at least hypothetically. The conclusions shall state the final findings (could be in terms of percentages) compared to the hypothetical ones and to the bibliographic studies.
Experimental Methods
Paragraph 88. Describe/Justify why the authors chose 9 blades.
Paragraph 92. How was the best fit assured to compare/evaluate the errors? What were the best fit planes considered?
Figure 1. Why is the Reverse model comparison flow back to the Geometric modelling. Add a note to the arrow in the flowchart.
Paragraph 107. Add information related to the measuring accuracy of both the CMM machine and the noncontact scanner.
Paragraph 127. Replace the ‘noise’ word. Same for paragraph 136.
Paragraph 129. What was the tolerance for the STL file conversion? Also, STL acronym should be defined.
Paragraph 140. In what terms did the two measuring devices differ? Again, how were the two measured parts aligned if the measuring points differ? This is highly important and related to the measuring accuracy of each measuring device. Please describe in more details.
Paragraph 142. The misalignment was considered for all nine levels of the rotor? It has to be mentioned in the text.
Paragraph 156. The dimensions of the rotor must be mentioned in the main text, in order have an overview of what the ±0.1 and ±0.5 mm means. How did the nominal and critical values were chosen? Based on what aspect?
Paragraph 161. Figure scale must be modified to be clearer.
Paragraph 216. Mention the ‘engineering tolerance of the clearance’ in the main text.
Paragraph 229. The engineering tolerance was set just to 0.1 mm? Shouldn’t it ±0.1 mm?
Paragraph 258. Authors mention that ‘The first four levels of blades exhibited poor surface quality…’. What do you mean by this? The surface presented a high roughness, defects, curl surfaces, etc.? What is the roughness found and how was it measured?
Paragraph 262. What RP method and material has been chosen for the jig fabrication? Where there any tolerances given to the printing parts? The method is highly important as it can generate substantial tolerance deviation from the dimensional accuracy point of view. Describe this in the main text.
How was the machining process evaluated? There is no mentioning of any final visual inspection, CMM evaluation after machining, roughness etc.
The results must be better explained and presented together with the novelty of the paper and compared to the existing stat of the art.
In the current form, the paper is viewed more in a report-form rather than a research article.
An encouragement to the authors is that they should try the metal 3D printing of such part, finding the best orientation and parameters, post-process (machining and NDT) and compare the quality, precision and time efficiency of both process.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
General comment
The authors comment is accepted. Anyway, for future work, you may also consider publishing similar results or another paper more focused on the manufacturing topic in the journals mentioned in the previous review (Processes, Micromachines, Materials etc.)
Abstract
Line 26: Please choose between either “roughness of the surface” or “quality of the surface”. They essentially express the same thing and make the sentence sound pleonastic.
Line 27: “The processed rotor can meet the requirements of flow test and dynamic balance…” à This is a rather bold statement which is also mentioned in the conclusions. However, no paragraph on this topic or any testing evidence is provided in the current paper. How was this verified? Which testing set-up was used? Where the results compared to the performances of the original turbomolecular pump? From my knowledge, turbomolecular pump rotors are highly sensitive equipment which can go as fast as 90,000 RPM while using magnetic bearings, so they are not easy to test and validate.
Introduction
Line 49: The word “aircrafts” does not exist (“aircraft” does not have a plural form). Please review.
Experimental Methods
Line 104: Now that the problem of the word “nine” is clarified, the expression can be rewritten as follows: “…a turbomolecular pump rotor with nine turbine stages that has been applied…”.
Lines 123-124: Please rephrase as follows: “A five-axis horizontal machining center was used to mill an aluminium alloy block in order to obtain the turbomolecular pump rotor.”
Line 139 and paragraph 2.1.2.: In the first part of the paper the word “stage” is used to define the turbomolecular pump components. After that, the word “level” is used. I advise you to try using the same designations in the whole paper to avoid confusions. The word “stage” is widely used to define the structure of bladed machinery, regardless of its type, and it should be always used for this purpose. Also, avoid mixing “blade” with the stage number. The stage number is linked with the turbine assembly. It should be always “1st turbine stage, 2nd turbine stage” etc., and not “1st stage (level) blades, 2nd stage (level) blades” etc. Please consider this for all the rest of the paper also as the incorrect designations are repeated throughout the entire paper.
Line 167: Replace “all levels of blades” with “all turbine stages”.
Lines 169-173: As I mentioned above, the using of the word “blade” to define the turbopump stage leads to problems in understanding what is described. Please be more consistent in this regard. In my opinion, the sentences 169 to 173 shall be reviewed accordingly. Please find below an example:
“Figure 5(a) illustrates the positioning of the first and second turbine stages. After positioning and file transformation for the entire assembly was performed, the files were exported to the NX CAD. According to the degree of curvature of the blades, the turbomolecular pump rotor geometric model was reconstructed, as depicted in Figure 5(b).”
Line 184: Please rephrase “…the CAD model shall be corrected”.
Paragraph 2.1.4: The authors mention that the error threshold for the comparison between the CAD model resulting from the scanned data and the one constructed was set at +/-0.5 mm maximum. Also, a difference of 0.1 mm was obtained by comparing the two models as declared following the first review, however, without including the higher values occurring at the tip of the blades. Please include these aspects in the paper. The lack of this information could confuse the potential readers as the first intention is to analyse Figure 6 and see that errors higher than 0.1 mm were obtained, statement which, according to the authors, is not true.
Line 195: the statement regarding the tools supplier looks like it was thrown just to be there. Please rephrase the statement. Example: “Standard length (80mm) or elongated cutting tools (100-150mm) from CMTec Taiwan were selected for machining according to the designated range.”
Line 204: the phrase should use past tense (“…rotor used 17 tools”).
Line 205: please rephrase as follows: “In toolpath planning, the rotor blades were thin and long, leading to the possibility of generating considerable vibration.”
Lines 207-208: The use of “cut” is repeating. Please rephrase as follows: “The first two segments were machined using cutting tools…”. Same for line 209.
Line 262: Figure 8 should be under the paragraph from 3.1.
Results and discussions
Line 307: introduction of the block jigs to help avoid the blade chattering phenomenon is too direct. The sentence should be rephrased. Example: “In order to limit the freedom of the opposing blades and to suppress chatter during machining, several block jigs were designed, as shown in Figure 12.”
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
