Determination of the Mechanical Tensile Characteristics of Some 3D-Printed Specimens from NYLON 12 CARBON Fiber Material
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
There is no novelty in the article and its look like lab. report.
Author Response
Please see the attached file: 'technologies-3771007 - Reviewer 1.pdf', which includes all replies
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
The manuscript is generally well written, and the methods are clearly described, allowing for reproducibility. The results are promising; however, some aspects still require refinement before the manuscript can be considered for publication. Below are a few suggestions that may help strengthen the overall quality and clarity of the work:
1) The introduction could benefit from additional detail. In particular, it would be helpful to briefly introduce the role of Finite Element Modeling (FEM) in this study, including references to relevant literature. This will help set the stage for its significance in the context of the work.
2) For some samples in Figure 1, it is difficult to clearly identify the location of fracture or necking. Consider adding dashed lines or arrows to highlight these regions, especially where the damage is subtle or incomplete.
3) The manuscript discusses the use of Digital Image Correlation (DIC), but currently does not show any corresponding strain maps. Including a few strain distribution images could significantly enhance the discussion, particularly in terms of visualizing failure concentration and supporting your interpretation of the results.
4) Specimen 3 appears to notably skew the Poisson’s ratio values, in both Table 1 and Table 2. It might be worth applying an outlier detection method to assess whether this data point should be excluded. For instance, removing Specimen 3 from Table 1 would shift the average Poisson’s ratio from 0.48 to approximately 0.51, a significant difference, especially since these averages seems to be used in the finite element simulation models.
5) There seems to be some inconsistency between Section 2.4 (which mentions displacement boundary conditions) and the Results section (which describes a distributed force applied to 10 nodes). Could the authors clarify exactly how the boundary conditions were applied in the simulation, and ensure the description is consistent throughout the manuscript?
6) The current comparison seems to focus on matching the simulation to a specific force value. A more informative approach might be to compare the full stress-strain curves from the simulation and the experiments. This would provide a clearer picture of how well the simulation captures the mechanical response of the material.
7) The anisotropy in the printed specimens is attributed to the interfaces between filaments. However, it’s unclear whether these interfaces were explicitly modeled in the simulations. If they were not, could the authors explain the rationale behind this choice? And if they were included, a brief description of the modeling approach would be helpful.
Overall, the results are promising and the experimental portion is solid. However, the finite element modeling, which is a critical component of the manuscript, requires additional clarification and possibly further development to be considered for publication.
Author Response
Please see the attached file: 'technologies-3771007 - Reviewer 2.pdf', which includes all replies.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
I would like to express my gratitude to the authors for their contribution. This work addresses the influence of print orientation on the mechanical properties of 3D-printed composite materials. Their work not only provides fundamental insights into the anisotropic behaviour of materials but also opens up new possibilities for industrial applications.
I have added my comments on each section for your review.
Introduction
Although the manuscript mentions the application in shallow water well drilling systems and the use of fused filament fabrication (FFF), I believe that it is not sufficiently clear what type of component is intended to be manufactured and how this relates to the specific requirements of such systems.
In my opinion, a more developed introduction should include specific information on the geometry, function and mechanical requirements of the component in question, as well as a more detailed description of the printing process and its relevance in the context of the proposed application. This type of information would contribute to a better contextualisation of the study and allow for a more accurate assessment of its relevance and originality. All of this should be supported by current bibliography.
Materials and methods
The standard used to perform the tests must be included.
It would be useful to include a brief explanation of why each step is important to ensure the quality and consistency of the samples. A visual graph of the trajectories should also be included.
Results
The data are presented in a coherent manner, but to give greater depth I would include:
- Comparison between orientations: A visual or tabular summary directly comparing the maximum displacements and stresses between the three printing orientations could facilitate interpretation.
- Additional validation: Although the correlation with the experimental data is good, a discussion of possible sources of error or uncertainty in the model could be added.
Conclusions
The conclusions are a little sparse. To enrich the article, I would add three points that I find interesting.
- Discuss how the results obtained may influence the design of components for specific applications, such as water well drilling systems. For example, highlight that lateral orientation (0°) is the most suitable for parts subjected to static or dynamic loads due to their greater strength and rigidity.
- Propose practical recommendations for optimising print orientation based on the mechanical requirements of the parts. For example, suggest that critical parts be printed in lateral orientation to maximise strength, while less demanding parts could take advantage of other orientations to reduce costs or printing times.
- Include a brief discussion of the limitations of the study, such as the lack of analysis of other printing parameters (infill density, infill pattern type, printing speed) or the absence of fatigue testing and behaviour under cyclic loads.
Comments for author File: 
Comments.docx
Author Response
Please see the attached file: 'technologies-3771007 - Reviewer 3.pdf', which includes all replies.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for Authors
- What was the reason behind selecting Nylon 12 Carbon Fibre for shallow water well drilling components?
- Why were three distinct printing orientations (horizontal, vertical, and lateral) chosen for this study?
- What is the significance of the thermal annealing process at 80 °C for 5 hours in the sample preparation?
- How does Digital Image Correlation (DIC) enhance the accuracy of strain measurements during tensile testing?
- Why did the laterally printed (0°) specimens exhibit the highest tensile strength and stiffness?
- What does the variation in Poisson’s ratio across different orientations indicate about the anisotropy of the material?
- How well did the finite element analysis (FEA) results correlate with experimental data for each print orientation?
- What boundary conditions and loading scenarios were applied in the FEA to simulate the tensile tests?
- Which print orientation is most suitable for load-bearing components in drilling applications, and why?
Author Response
Please see the attached file: 'technologies-3771007 - Reviewer 4.pdf', which includes all replies.
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for Authors
The submitted manuscript investigates the mechanical tensile properties of nylon 12 carbon fiber specimens fabricated in different orientations via fused filament fabrication (FFF) 3D printing. The article is concise, clear and involves relevant research areas. The article has the following comments:
- Introduce the importance of nylon 12 carbon fiber materials in engineering and compare them with other carbon fiber polymer composites.
- Indicate the carbon fiber volume fraction in these 3D printed nylon 12 carbon fiber composite specimens. Different fiber volume fractions in composite materials significantly affect their mechanical properties.
- Show the scale of the images in Figure 1.
- Provide more details of the tensile test, such as sample dimensions, crosshead speed settings, and reference standards.
- Show micrographs or scans of 3D printed specimens of nylon 12 carbon fiber material to illustrate 3D print quality and porosity.
- Present finite element analysis (FEA) results for different fiber volume fractions
Comments on the Quality of English Language
The article needs minor revision for language and grammar.
Author Response
Please see the attached file: 'technologies-3771007 - Reviewer 5.pdf', which includes all replies.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
The response provided by the authors are satisfactory.
Author Response
Coments 1. The response provided by the authors are satisfactory.
Response 1: We appreciate the reviewer’s comment confirming the quality of the English language.
Although no further revisions were requested, the manuscript was improved overall by including additional methodological details (specimen thickness, print path configuration, support removal, and annealing) and representative micrographs. These additions enhance reproducibility and strengthen the research design.
As an additional revision, the bibliography has been carefully re-verified to ensure that all cited references are accurate, accessible, and relevant to the study.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
Many thanks to the authors for the corrections made.I would appreciate it if, for future revisions, you could provide a direct response to each reviewer, itemizing the changes and where they have been modified in the document.The introduction, results, and conclusions are now more complete.
However, the materials and methods section remains unclear regarding sample manufacturing. This test must be reproducible, so I would appreciate it if you could include a graphic of the print pattern or a description, including whether all the layers begin with the same orientation, the starting point, etc. Is there contouring of the sample? Is there reinforcement?
Author Response
Comments 1: Many thanks to the authors for the corrections made.I would appreciate it if, for future revisions, you could provide a direct response to each reviewer, itemizing the changes and where they have been modified in the document.The introduction, results, and conclusions are now more complete.
However, the materials and methods section remains unclear regarding sample manufacturing. This test must be reproducible, so I would appreciate it if you could include a graphic of the print pattern or a description, including whether all the layers begin with the same orientation, the starting point, etc. Is there contouring of the sample? Is there reinforcement?
Response 1:
We sincerely thank the reviewer for the constructive feedback. In this revised version, Section 2.1 (Sample Manufacturing and Preparation, page 4, paragraphs 7–10) has been substantially expanded to ensure full reproducibility of the experimental procedure. Specifically, the following clarifications were added:
-Each printed layer was initiated at the front-left corner of the specimen and followed a consistent clockwise toolpath.
-Three outer contour lines (perimeters) were applied in order to reinforce the external geometry of the specimens.
-Reinforcement was provided intrinsically by the chopped carbon fibers uniformly dispersed in the PA12-CF filament; no additional CAD features (e.g., ribs or shells) were introduced.
-Support material (SR-30) was automatically generated by the slicing software and subsequently removed using the SCA-1200HT washing station.
-The material orientation relative to the loading axis was preserved consistently across all three configurations (A – 45°, B – 90°, C – 0°).
In addition to this detailed description, a new Figure 2 (Section 2.1, page 5) has been included, illustrating the internal toolpath strategy (infill and perimeters) for each print orientation. Additionally, extrusion temperature, nozzle size, and layer thickness were specified in Section 2.1 to further improve reproducibility.
We believe these additions make the manufacturing process transparent and reproducible, thereby directly addressing the reviewer’s concern.
We trust that the additional description and the inclusion of Figure 2 provide sufficient detail to ensure full reproducibility of the sample manufacturing process, as requested.
To provide a coherent closure, a short paragraph was also added in the Conclusions section, emphasizing that the additional methodological steps (support removal, annealing, and microstructural inspection) ensured specimen consistency and reproducibility.
In addition, to further strengthen the transparency and reproducibility of the experimental design, the Materials and Methods section has been expanded with the following elements:
-The specimen thickness (5 mm) is explicitly indicated in accordance with ISO-527.
-Representative optical micrographs at 100× and 200× magnifications have been included (Figure 3), highlighting filament alignment and interlayer adhesion for each build orientation. These microstructural observations support the mechanical behavior reported in the Results section.
-Detailed descriptions and illustrative figures of the post-processing steps have been added: support removal in the SCA-1200HT washing station (Figure 4) and thermal annealing inside the heated chamber of the MakerBot Method X Carbon Fiber printer (Figure 5). These procedures ensured consistent specimen quality and improved dimensional stability prior to mechanical testing.
We believe these additions provide a more complete description of the research design and experimental methodology, thereby directly addressing the reviewer’s comment.
As an additional revision, the bibliography has been carefully re-verified to ensure that all cited references are accurate, accessible, and relevant to the study.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for Authors
The article can be accepted for publication.
Author Response
Comments 1: The article can be accepted for publication.
Response 1: We sincerely thank the reviewer for the positive evaluation and for recommending the article for publication. We highly appreciate your supportive feedback.
Additional clarifications
Although no specific revisions were requested, the manuscript was further improved in line with the general evaluation criteria. In particular, additional methodological details (specimen thickness, print path configuration, support removal, and annealing) and representative micrographs were included in Section 2.1, and the Conclusions were refined accordingly. These additions enhance the transparency and reproducibility of the study.
As an additional revision, the bibliography has been carefully re-verified to ensure that all cited references are accurate, accessible, and relevant to the study.
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for Authors
The submitted manuscript investigates the mechanical tensile properties of nylon 12 carbon fibre specimens fabricated in different orientations via fused filament fabrication (FFF) 3D printing. The deformation of the samples was measured using Digital Image Correlation (DIC), a non-contact optical technique. The revised article has clear ideas, is concise and logical, and involves relevant research fields. The article has the following further comments:
- Indicate the thickness of the tensile specimen.
- Demonstrate the quality of 3D printed nylon 12 carbon fibre specimen in the micrographs.
Comments on the Quality of English Language
The article needs minor revision for language and grammar.
Author Response
Comments 1: The submitted manuscript investigates the mechanical tensile properties of nylon 12 carbon fibre specimens fabricated in different orientations via fused filament fabrication (FFF) 3D printing. The deformation of the samples was measured using Digital Image Correlation (DIC), a non-contact optical technique. The revised article has clear ideas, is concise and logical, and involves relevant research fields. The article has the following further comments:
1.Indicate the thickness of the tensile specimen.
2.Demonstrate the quality of 3D printed nylon 12 carbon fibre specimen in the micrographs.
Response 1: We thank the reviewer for this observation. In response, we have explicitly mentioned the thickness of the printed tensile specimens, which is 5 mm, in Section 2.1 (Sample Manufacturing and Preparation), in accordance with the ISO-527 standard. This detail improves the clarity and reproducibility of the experimental procedure..
We fully agree that visual evidence of the specimen quality is important for evaluating the reliability of the manufacturing process. Accordingly, we have included a new figure (Figure 3) containing representative micrographs of the printed specimens in the three orientations used: (a) horizontal orientation (A – 45°), (b) vertical orientation (B – 90°), and (c) lateral orientation (C – 0°). The micrographs highlight differences in filament alignment and interlayer adhesion, and these microstructural features are correlated with the mechanical behavior observed during tensile testing. A corresponding paragraph has been added to Section 2.1 to describe and discuss these findings.
To provide a coherent closure, a short paragraph was also added in the Conclusions section, emphasizing that the additional methodological steps (support removal, annealing, and microstructural inspection) ensured specimen consistency and reproducibility.
Additional clarifications
To further improve the transparency of the research design, additional methodological details were included in Section 2.1. Specifically, the print path configuration (starting point, toolpath orientation, and contouring strategy) was explicitly described to ensure reproducibility as can be seen in Figure 2. Furthermore, two post-processing steps were detailed:
-Support removal using the SCA-1200HT washing station (Figure 4), performed identically for all specimens.
-Thermal annealing in the heated chamber of the MakerBot Method X Carbon Fiber printer (Figure 5), aimed at improving dimensional stability and interlayer bonding.
These additions complement the information on specimen thickness and the inclusion of representative micrographs (Figure 3), thereby providing a more robust and transparent research design.
As an additional revision, the bibliography has been carefully re-verified to ensure that all cited references are accurate, accessible, and relevant to the study.
Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
Comments and Suggestions for Authors
Dear Authors,
I would like to sincerely thank you for the time and effort devoted to implementing the modifications I suggested. After reviewing the revised version of the manuscript, I confirm that I have no further comments to add.
Thank you once again for your work and collaboration.
