Potentials of Numerical Methods for Increasing the Productivity of Additive Manufacturing Processes

Round 1

Reviewer 1 Report

The following comments are suggestions to improve the manuscript numbered " ceramics-2138654”:

The introduction is short and needs some improvement.

Please use a quantitively scale instead qualitative one in figure 1. For example, use 80% instead very relevant.

The size and shape of the sample are related to its position on the manufacturing platform. What do you suggest for this problem when the shape and space between samples change?

Please add an economic study related to the manufacturing cost and benefit of the proposed model.

The following papers are suggested for the introduction section:

Laser additive manufacturing of bulk and powder ceramic materials: mathematical modeling with experimental correlations

Development of paste extrusion-based metal additive manufacturing process

 

Build position-based dimensional deviations of laser powder-bed fusion of stainless steel 316L

Author Response

Thank you very much for the numerous comments, which were very helpful to increase the quality of our paper.

 

*The introduction is short and needs some improvement.

 COMMENT:

We have revised the introduction and hope that an improvement has been achieved through the addition of various explanatory notes as well as appropriate literature references.

 

*Please use a quantitively scale instead qualitative one in figure 1. For example, use 80% instead very relevant.

 COMMENT:

Since the costs incurred in the individual process steps depend significantly on the component geometry and the AM technology and material used, the cost shares vary greatly. The selected representation is only intended to give a general impression of the cost distribution, but must be examined in detail for each individual case.

We have added the corresponding explanation in the text.

 

*The size and shape of the sample are related to its position on the manufacturing platform.

 What do you suggest for this problem when the shape and space between samples change?

 COMMENT:

We are afraid that we do not understand this question. But maybe the meaning is: The optimization of the placement of the sample(s) on the platform yields some position of these sample(s) on the platform. Now, if new samples need to be placed, the shape of the new samples or the (needed minimal) space between samples (existing or new) can change. Then, of course a new optimization of the placement has to be carried out (like described in Section 6.).

Moreover, we added the following sentence to the conclusion to show the universality of the approach to optimize placements:

 “The phi-function technique can be used for analytical description of non-overlapping and distance constraints for differently shaped objects (see, e.g., [40]).”

 

*Please add an economic study related to the manufacturing cost and benefit of the proposed model.

 COMMENT: From our point of view, it is impossible to provide such an economic study since the proposed model is currently not implemented and manufacturing cost and benefit surely depend on several circumstances. We are also not aware of any studies for the current procedure that deal intensively with manufacturing costs and can make generally valid statements in this context. This is certainly due to the fact that the costs and their distribution are strongly dependent on the component geometry, the selected AM technology and the material, among other things. But we will take up this topic in future works - thank you for this suggestion.

 

*The following papers are suggested for the introduction section:

 1) Laser additive manufacturing of bulk and powder ceramic materials: mathematical modeling with experimental correlations

 2) Development of paste extrusion-based metal additive manufacturing process

 3) Build position-based dimensional deviations of laser powder-bed fusion of stainless steel 316L

 COMMENT:

Thank you for the suggested papers. These are very interesting, but we made a conscious decision not to add them.

• This work shows the importance of mathematical methods for the development of manufacturing processes and the increase of process understanding. However, it deals with the simulation of the melt pool during laser heating and does not fit our packing problem.
• This is one of many papers describing different approaches to making components from various AM technologies and materials. However, this is not the focus of our work.
• This work shows in an impressive way that the positioning of the component during manufacturing can also have an influence on its quality. This should also be taken into account in the future when automatic arrangement of the components takes place. However, this idea belongs to the reviewer, so we refrain from attributing it to us in our paper.

Reviewer 2 Report

In this manuscript, the authors report the use of a mathematical method based on the phi-function technique to optimize the arrangement of cylindrical components on a 3D-printer bed to reduce the manufacturing costs. The authors demonstrated an improvement of 70% of printer bed utilization compared to traditional automatic tools using bounding box principles. Overall, this is an interesting work with valuable content. The manuscript could be further improved by addressing minor points listed below. Few sections are occasionally confusing (mainly sections 1 and 2), as it is sometimes challenging for the reader to understand if the authors are talking about additive manufacturing in general, or additive manufacturing applied to ceramics only. Indeed, few claims would not apply to the processing of other materials. The sections describing the results are better written and clearer.

Please review and address the comments below:

1.      Abstract, Line 18 and Introduction, Line 36: Authors should consider adding the word “ceramic” front of “components”, as this article is focused on the fabrication of ceramics. Indeed, the claim stating that an enormous effort would be required without additive manufacturing does not apply to other types of materials, such as thermoplastics or elastomers.

2.      Introduction, Line 38: “such as” and “e.g.” are redundant.

3.      Introduction, Line 39: Could the authors provide a reference describing the sentence?

4.      Introduction, Line 43: Could the authors name examples of “few individual areas of application”?

5.      Introduction, Line 57: Please review the writing of “geometrically highly complex component geometries”. The formulation is too long with redundant information.

6.      Section 2.2.: This section could gain in clarity. I don’t understand under which category falls the additive manufacturing of ceramics. Is it considered as indirect technology, direct technology, or both? Or all techniques described in this section are related to the processing of ceramics? If this is the latter case, then please consider replacing the first sentence of the section with: “The multitude of AM technologies applicable to the manufacture of ceramics can be divided into two different groups: indirect technologies and direct technologies.” That would be much clearer for the reader that may come from a different background.  

7.      Section 2.3., Line 134: Please review the sentence “principle of the bounding box for automatically component arrangement”, which does not seem grammatically correct.

8.      Section 2.3., Line 166: Please review the construction of the sentence “Especially for series production this needs to be optimized, because efficient use of the building envelope is more critical in this case, for classical prototyping there is more flexibility.”. The current sentence is too long and unclear.

9.      Section 2.3., Line 175: I do not understand the terminology “vision” used in this sentence. Is it the name of a software? Does it describe the operating mode of the software described in this section?

10.   Section 3.2, Line 221: What does mean “NP-hard”?

11.   Section 4.1, Line 335: Why there is a need for two vectors (a1 and a2 / s1 and s2)? It does not seem to be clearly explained.

12.   Section 4.2, Line 352: There might be a typo in the caption for panel c).

 

Author Response

Thank you very much for the numerous comments, which were very helpful to increase the quality of our paper.

 

*In this manuscript, the authors report the use of a mathematical method based on the phi-function technique to optimize the  arrangement of cylindrical components on a 3D-printer bed to reduce the manufacturing costs. The authors demonstrated an improvement of 70% of printer bed utilization compared to traditional automatic tools using bounding box principles. Overall, this is an interesting work with valuable content.

COMMENT:

Thank you very much!

 

*The manuscript could be further improved by addressing minor points listed below. Few sections are occasionally confusing (mainly sections 1 and 2), as it is sometimes challenging for the reader to understand if the authors are talking about additive manufacturing in general, or additive manufacturing applied to ceramics only. Indeed, few claims would not apply to the processing of other materials. The sections describing the results are better written and clearer.

COMMENT:

We have revised the introduction and hope that an improvement has been achieved through the addition of various explanatory notes as well as appropriate literature references.

 

 

Please review and address the comments below:

 

*1. Abstract, Line 18 and Introduction, Line 36: Authors should consider adding the word “ceramic” front of “components”, as this article is focused on the fabrication of ceramics. Indeed, the claim stating that an enormous effort would be required without additive manufacturing does not apply to other types of materials, such as thermoplastics or elastomers.

COMMENT:

There are many component geometries that can only be realized using AM technologies. Therefore, these AM technologies are also interesting for polymers and elastomers.

e.g.: https://www.mdpi.com/1996-1944/15/22/7954

The question of optimal packing of the components on the build platform arises for all material classes, so we have added "ceramics" only where it is needed.

 

*2. Introduction, Line 38: “such as” and “e.g.” are redundant.

COMMENT:

We deleted "e.g.,".

 

*3. Introduction, Line 39: Could the authors provide a reference describing the sentence?

COMMENT:

We added some references.

 

*4. Introduction, Line 43: Could the authors name examples of “few individual areas of application”?

COMMENT:

We added some references.

 

*5. Introduction, Line 57: Please review the writing of “geometrically highly complex component geometries”. The formulation is too long with redundant information.

COMMENT:

We deleted "geometrically".

 

*6. Section 2.2.: This section could gain in clarity. I don’t understand under which category falls the additive manufacturing of ceramics. Is it considered as indirect technology, direct technology, or both? Or all techniques described in this section are related to the processing of ceramics? If this is the latter case, then please consider replacing the first sentence of the section with: “The multitude of AM technologies applicable to the manufacture of ceramics can be divided into two different groups: indirect technologies and direct technologies.” That would be much clearer for the reader that may come from a different background. 

COMMENT:

Almost all direct or indirect AM technologies known for polymers and metals have now been tested and used for AM of ceramics. We have revised the paragraph and hope that it is now easier to understand.

 

*7. Section 2.3., Line 134: Please review the sentence “principle of the bounding box for automatically component arrangement”, which does not seem grammatically correct.

COMMENT:

We revised it to "...for automatic component arrangement"

 

*8. Section 2.3., Line 166: Please review the construction of the sentence “Especially for series production this needs to be optimized, because efficient use of the building envelope is more critical in this case, for classical prototyping there is more flexibility.”. The current sentence is too long and unclear.

COMMENT:

We revised it to: “Especially for series production this needs to be improved, because efficient use of the building platform is more critical in this case. For classical prototyping, where typically only individual components are manufactured and the build platform is not fully loaded, there is more flexibility.”

 

*9. Section 2.3., Line 175: I do not understand the terminology “vision” used in this sentence. Is it the name of a software? Does it describe the operating mode of the software described in this section?

COMMENT:

Please excuse the misunderstanding, there is no software tool yet, but this is the target / vision for the next work. We revised the sentence.

 

*10.Section 3.2, Line 221: What does mean “NP-hard”?

COMMENT:

We have deleted the notion "NP-hard" since a reasonable discussion would need several pages, in particular containing the introduction of some classes of computational complexity (like P and NP), the discussion of one of the most important problems of computer science whether P=NP or not, and the decision version of an optimization problem. Note that, roughly speaking, decision problems in P can be solved in a time limit that is bounded by a polyniomal depending on the size of the input data. For NP-hard problems, this is not the case if we assume P is different from NP.  

 

*11.Section 4.1, Line 335: Why there is a need for two vectors (a1 and a2 / s1 and s2)? It does not seem to be clearly explained.

 

*12.Section 4.2, Line 352: There might be a typo in the caption for panel c).

COMMENT for *11. And *12:

According to the questions 11 and 12, we have completely rewritten the part between lines 325 and 352 (submission) resp lines 341-398 (revised version).