Effects of Printing Angle, Infill Density and Cryogenic Pre-Treatment on the Tensile and Flexural Properties of FFF-Printed PLA

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The current work investigates the influence of printing angle and infill density on the mechanical properties of as-printed PLA and cryogenic treated components. There are some issues to be considered as follows:

• The title should be adjusted to accurately describe the current manuscript contents.
• The abbreviation "FFF" should be defined at its first appearance in the abstract and introduction sections. 
• The problem statement should be defined in more detail. 
• The number of fabricated and tested samples of each selected group should be presented.
• In Figures 3, 4, and 5, the directions and axes related to the build direction should be labelled.
• Figures 6 to 15 should display the standard deviation of the measured values.
• There are anisotropic characteristics for the as-printed fused deposition modeling components. The authors should illustrate this issue. 
• The reasons for selecting the applied printing angles and infill density percentages should be illustrated in more detail.
• The discussion should be supported by relevant references to justify the presented results and analysis.
• The contribution and novelty of the current research are not obvious throughout the current manuscript.
• The authors should carefully revise the selection of technical expressions; some expressions should be replaced, such as expressions of "fresh" and "frozen". 
• The conclusion should focus on the main results, contributions, novelty, direct application, and future perspective of the current study.

The current manuscript should be resubmitted for another review after considering the above comments and recommendations.

Comments on the Quality of English Language

The authors should carefully revise the selection of technical expressions and words, in addition to avoiding grammatical errors.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors investigated the role of infill density and printing angles on tensile end flexural properties of PLA samples. In addition a study on the cryogenic treatment was added. The topic is in line with the journal but was deeply studied in the literature, it is crucial a deep explanation of the novelty. Experimental part is well organized but very common. English is correct and references are proper and well commented. 

 

The role of printing angles is crucial also considering the in-plane angle (10.1007/s00170-025-15101-0) please add it in the introduction.

 

Some impacts of process parameters on shape memory properties and surface qualities (fuzzy skin and ironing) should be mentioned in the introduction, with proper references.

 

The novelty of the paper is unclear and must be specified by the authors.

 

Line 12: the authors wrote about polymer composites but bare PLA was used in the investigation.

 

Line 16, PLA is definitely not used for its mechanical properties, please rephrase it.

 

Lines 111-115 please shorten up the text considering Table 1.

 

How many replicas were manufactured and tested for each scenario?

 

Figures from 6 to 15: it is mandatory to add error bars. Standard deviations must be also considered in the discussion, otherwise the comparison is not validable.

 

Images of the fracture zones are highly recommended.

 

Considering the full factorial Plan proposed an ANOVA analysis is deeply encouraged, in order to determine the statistical significance of the parameters and their interaction on the mechanical properties.

 

In the conclusions some applications and future developments are needed.

Author Response

Please see atached document. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript is significantly improved. Most of the review comments and recommendations are well addressed. However, some minor issues still need to be considered as follows:

• The manuscript text should be revised carefully to avoid data redundancy or repeated words, for example, at line# 338. 
• The conclusion points could be more focused. Some expressions, such as "fresh series," at line# 561, should be replaced. 

Author Response

Please see atached document.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Several important modifications were applied by the authors. All the questions were answered. Therefore I recommend the acceptation 

Author Response

Please see atached document.

Author Response File: Author Response.pdf