Analysis of the Dimensional and Shape Accuracy and Repeatability of Models Produced in the Process of Additive Extrusion of Thermoplastic Polymers Using Fused Filament Fabrication Technology
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this manuscript, the authors reported a detailed dimensional analysis of the accuracy of Fused Filament Fabrication (FFF) 3D printing technology. The reported data are strictly connected to the type of material used, the diameter of the filament, and the model of the 3D printer used in this study. Overall, the manuscript needs to be revised in some parts, to avoid typos and to explain better concepts and statements that are difficult to understand. Some issues should be clarified before publication:
1. In “Materials and Methods” more specifications about the properties of PLA should be added, e.g. in terms of suppliers.
2. In line 56 can you specify the unit measures?
3. Line 68: there are no symbols in Table 1
4. Please revise the measure units in Table 1 regarding superscripts.
5. Lines 69-70: is not clear what the authors said about the definition of the following parameters “sequential printing option, layer height 0.2 mm, quality, and generic PLA option”. Can you provide a better explanation of what you are stating here?
6. Lines 74-75: what does it mean “calibrated the table leveling to properly compensate for the curvatures”? Can you explain better the calibration process?
7. Figure 4: the color legend is not visible; can you enlarge the picture or improve the quality of it?
8. Lines 113-115: The statement is not completely clear; can you give a better explanation? Do you have some explanations for these displacements?
9. Lines 121-122: The additional analysis could be included in the Supporting Information, leaving in the main text only the conclusions and the analysis of the obtained data.
10. Lines 135-137: Did the authors try to minimize the problem through a more accurate calibration or by changing some printing parameters?
11. Lines 154-155: where are the cited Gaussian plots of each dimension?
12. Line 157: the vertical blue line is referred to which graph?
13. Lines 161-164: The authors stated that the average value is 4.99 mm, same value for the median of the measurements. How can they calculate this data?
14. Figure 8: Please, consider using a dotted straight line to connect the points. Is the Dimensional Value referred to the average or the median measurement?
15. Lines 185-189: Did you have an explanation about why the angles are less than the nominal values?
16. In Table 3 a comparison among all data is reported. Did you consider to report the deviation in % respect to the nominal value, to make the comparison clearer?
17. Can you report the parameters used during the printing process? Did you optimize them before the dimensional analysis?
18. Lines 241-242: Please, check the reported value of the specific tolerance that is 30°. Is it correct?
19. Lines 247-249: Can you explain better what you stated in these lines?
20. The bibliography and references should be improved.
Author Response
Dear reviewer,
On behalf of all authors, I would like to thank you for taking the time to read our manuscript and put your comments, which allowed us to improve the quality of our work. Below you can find our answers related to each of your comments. The whole manuscript has been revised by using the track changes tool.
- In “Materials and Methods” more specifications about the properties of PLA should be added, e.g. in terms of suppliers.
We supplemented in table 1 a supplier name: Noctuo Ultra PLA filament (Gliwice, Poland).
- In line 56 can you specify the unit measures?
The unit has been attached (mm).
- Line 68: there are no symbols in Table 1
Table 1 has been supplemented with the required symbols.
- Please revise the measure units in Table 1 regarding superscripts.
Superscripts were improved.
- Lines 69-70: is not clear what the authors said about the definition of the following parameters “sequential printing option, layer height 0.2 mm, quality, and generic PLA option”. Can you provide a better explanation of what you are stating here?
We included an additional drawing with 3D printing parameters and the text is supplemented with the required information. Text added: Based on the STL template file, a machine code was created, the so-called Gcode (Figure). The printer was equipped with a nozzle with a diameter of 0.4 mm, the printing speed of the first layer was 20 mm/s, the printing speed was 60 mm/s, the head temperature: 215 áµ’C, the layer height was 0.2 mm, the thickness of the lower and upper layers (all layers they have the same thickness, their speed is different, the first one is 20 mm/s and the last one is 40mm/s), additionally, a heated table with a temperature setting of 60°C was used. 100% infill was used during printing. Cooling was turned on from the second layer to 100%. The research defined, among others, the following parameters: sequential printing option, layer height ,,0.2 mm QUALITY” and dedicated option for PLA in PrusaSlicer ,,generic PLA”. Sequential printing, which means that the printer creates each model separately and not layer by layer, all models at once.
- Lines 74-75: what does it mean “calibrated the table leveling to properly compensate for the curvatures”? Can you explain better the calibration process?
Text added: The purpose of calibrating the first layer is to set the appropriate distance between the nozzle tip and the worktable surface, i.e. one that ensures good adhesion of the filament path and slightly flattens its cross-section. This is about compensating for any unevenness of the table in the Z direction. The Prusa i3 mk3 printer has a built-in "PINDA" sensor that creates a current map of the table with each printout - in our case it was 16 points. The position in the X and Y direction (zeroing the axis) is performed by reaching the limit switches on each axis and obtaining the zero position. Original Prusa FFF printers have a sensor that detects the distance from the printing surface. During calibration, and before each print, the sensor measures the distance from the plate at a specific number of points arranged on the table surface in the form of a grid (it does not matter whether the plate is textured or smooth). These points are interpolated and used to create a virtual table mesh. If the bed has slight unevenness, the sensor will continue to accurately follow the surface consistent with the measured mesh while printing.
- Figure 4: the color legend is not visible; can you enlarge the picture or improve the quality of it?
Figure 4 has been corrected.
- Lines 113-115: The statement is not completely clear; can you give a better explanation? Do you have some explanations for these displacements?
Text added: The general inspection procedure in GOM software begins with the import and basing of CAD and live data.
CAD data contains information about all possible nominal geometric elements. Individual elements must be defined. The live data contains information about all extracted geometric elements, and individual elements must be created.
Once a nominal item and an actual item have been created, they can be compared using one or more checks. An inspection creates an inspection element as its result. Tolerances can be applied during the control definition process. The tolerance information is used to interpret the inspection result.
In a standard workflow, inspected items are constructed on CAD data. Current equivalents are not created manually, but generated from nominal elements by applying measurement rules. This procedure combines live elements with their nominal original, enabling parametric inspection.
The inspection results in inspection items that are distinct from the nominal and actual items on which they are based.
Geometric and dimensional analyzes that can be performed include:
- Comparing surface deviations
- Comparing dimensional deviations
- Geometric Dimensioning and Tolerancing (GD&T)
Surface comparison compares each CAD point to the mesh or vice versa.
The results are displayed in the form of a color map of deviations. Green areas indicate no deviations. Red areas indicate positive deviations. Blue areas indicate negative deviations. The color is applied to the CAD or mesh copy, depending on the option selected.
- Lines 121-122: The additional analysis could be included in the Supporting Information, leaving in the main text only the conclusions and the analysis of the obtained data.
Due to adding an additional table as Appendix 2 we decided to maintain the structure of our article to allow visualization of the described phenomena point-by-point, which also corresponds with the journal's template.
- Lines 135-137: Did the authors try to minimize the problem through a more accurate calibration or by changing some printing parameters?
The research study examined repeatability, not the impact of calibration and parameter optimization on the print result. Importantly for our study, the calibration effect and parameters had no impact on our study because the parameters were identical for each test object, and the level of calibration before the sequence to complete printing did not change in a measurable way. The conditions for each test object did not change during the entire study, which was crucial for the repeatability study.
- Lines 154-155: where are the cited Gaussian plots of each dimension?
We are very sorry for not putting the mentioned Gaussian plots – we attached all of them as Appendix A.
- Line 157 (240): the vertical blue line is referred to which graph?
The blue line refers to the GAUSS plot. We put all those kinds of lines for each plot in the Appendix A
- Lines 161-164: The authors stated that the average value is 4.99 mm, same value for the median of the measurements. How can they calculate this data?
We have 12 measurement samples, the middle dimensions are 4.98 and 5.00, so the median is the average of these numbers, i.e. 4.99. The average is exactly 4.9866666[6] so rounding it gives 4.99.
- Figure 8: Please, consider using a dotted straight line to connect the points. Is the Dimensional Value referred to the average or the median measurement?
We have modified the mentioned figure according to your comment. Thank you for this advice.
- Lines 185-189: Did you have an explanation about why the angles are less than the nominal values?
The level of belt tension has a significant impact on model accuracy, especially when both axes must be used simultaneously to produce a feature, causing angular dimensions or other features to deviate significantly from nominal values. Therefore, a new power transmission method should be considered for the remaining two directions.
- In Table 3 a comparison among all data is reported. Did you consider to report the deviation in % respect to the nominal value, to make the comparison clearer?
We agree with the reviewer, that for comparison a percentage value would be clearer, and would allow for better interpretation of the obtained results. However, a standardized approach for tolerances is an exact value (in our case mm). To keep standards, we decided to maintain values in mm.
- Can you report the parameters used during the printing process? Did you optimize them before the dimensional analysis?
Printing parameters were constant and not optimized. Printing parameters were dedicated for this material by PrusaSlicer. We put the default parameters in the beginning of chapter 2.2.
- Lines 241-242 (262): Please, check the reported value of the specific tolerance that is 30°. Is it correct?
Thank you for your deep analysis, you are right. It should be 0.30° - we put proper corrections
- Lines 247-249: Can you explain better what you stated in these lines?
The printing process depended on the degree of wear of consumable parts such as the nozzle or linear guides, which depended on the operating time of the printer, which for the tested one was 56 days of printing and 4,300 meters of extruded filament.
- The bibliography and references should be improved.
The required formatting has been made according to the journal’s requirements.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis work analyzed the dimensional and shape accuracy and the repeatability of samples produced by a technology based on layered extrusion of thermoplastic polymers using FFF - fused filament fabrication technology. It is critical for extrusion-based 3D printing. The research content is innovative and practical. Meanwhile, before publication, the following issues should be solved:
1. In the first paragraph of Introduction section, their relevant 3D printing work should be focused to enrich the text: https://doi.org/10.1007/s40820-023-01317-w
2. In Materials and Methods section, more detailed printing parameters should be added, e.g., printing speed, printing temperature, platform temperature, nozzle diameter and so on.
3. In Figure 1, the dimensions of pattern model have been mentioned (40*40*5). Meanwhile, the internal geometries are suggested to mark the dimensions.
4. In Figure 8, as mentioned “It can be observed that the difference between the extreme measurement values of 4.95 and 5.01 mm is 0.06 mm. However, the average value of the measurement results is 4.99 mm.”, only 12 points of data were obtained here, and it is recommended to test more points to get more accurate results.
5. In Figure 9, why do contours show different roughness?
6. Some formatted mistakes should be avoided, e.g., L.215 “,,”.
Author Response
Dear reviewer,
On behalf of all authors, I would like to thank you for taking the time to read our manuscript and put your comments, which allowed us to improve the quality of our work. Below you can find our answers related to each of your comments. The whole manuscript has been revised by using the track changes tool.
- In the first paragraph of Introduction section, their relevant 3D printing work should be focused to enrich the text: https://doi.org/10.1007/s40820-023-01317-w
Dear reviewer, a listed research work titled ”3D-Printed Carbon-Based Conformal Electromagnetic Interference Shielding Module for Integrated Electronics” does not have a connection with our research. The mentioned article takes into account electric measurements and analysis while our work is focused on dimension accuracy and quality analysis of AM-ed part. If you claim we should put this citation, we would be grateful for information about which part of the suggested article would be suitable for citation in our manuscript.
- In Materials and Methods section, more detailed printing parameters should be added, e.g., printing speed, printing temperature, platform temperature, nozzle diameter and so on.
We put additional information about the process at the beginning of chapter 2.2.
- In Figure 1, the dimensions of pattern model have been mentioned (40*40*5). Meanwhile, the internal geometries are suggested to mark the dimensions.
The unit has been adding (mm). The dimensions of internal geometries are shown in Figures 5, 9, and 11.
- In Figure 8, as mentioned “It can be observed that the difference between the extreme measurement values of 4.95 and 5.01 mm is 0.06 mm. However, the average value of the measurement results is 4.99 mm.”, only 12 points of data were obtained here, and it is recommended to test more points to get more accurate results.
We have 12 measurement samples, the middle dimensions are 4.98 and 5.00, so the median is the average of these numbers, i.e. 4.99. The average is exactly 4.9866666[6] so rounding it gives 4.99.
- In Figure 9, why do contours show different roughness?
A contours shape is related to the 3D-CAD software that we have used. It does not affect the measurements.
- Some formatted mistakes should be avoided, e.g., L.215 “”.
Thank you for this advice. We made a deep proof reading of the whole article once more.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors replied to all the reported points. The article should be accepted in the present form.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe suggestions have been well revised, it could be accepted in present form.
