Development Workflow for Manifolds and Fluid Components Based on Laser Powder Bed Fusion

Round 1

Reviewer 1 Report

This manuscripts presents a methodology for the development of hydraulic manifolds manufactured by LPBF. The proposed approach aims to guide the designer towards more efficient manufactured parts (in terms of cost and reliability). An overall scheme of the methodology divides the design process into planning, conceptualization, design and manufacturing. Finally a study case for the design of an hydraulic manifold is presented.

This research seems relevant and I would suggest the publication of it after some observations have been addressed:

1. I would suggest to break the Methodology into subsections the corresponding Design Stages. At several times of the review I was very confused in which part of Methodology was related to each part of the study case. A clear structure means that the manuscript is easier to read and understand.

2. Line 340: Can you specify the value-benefit analysis conducted. The current selection of the part to manufacture at this stage seems a bit arbitrary. Furthermore, you specify several concepts for assessment (L. 183-189). However, none of this conceps are discussed in the results.

3. L. 356, L. 359, Table 4: Do you mean 45° or 49°? In case of the latter, this value seems a bit tuned. Can you discuss what lead to the selection of this value (optimization, multiple simulation results, etc)?

4. L. 409: Can this be addressed in future work? If so, how do you think it can be addressed?

5. Table 6. Is there a way to quantify this evaluation such that gain or loss result can be retrieved? If the answer is no, what is the reason (complexity? data unavailable? further studies?)

6. The approach and the case study seems in general very interesting to me. However, I notice that the economic assessment results in a non-viable manufacturing approach (at least currently). A question to the authors that arises to me is: isn't it possible to assess economically the production of the part before the actual manufacture, or am I missing something? Why did you take the approach you took concerning this study case?

Author Response

Thank you very much for the detailed review and the interest in the presented work. All suggestions and comments of the review have been considered. Improvements were made in the areas mentioned:

• Each phase and the corresponding steps are now highlighted in the use case paragrahps to allow better reading and traceability of the steps. The use case follows the 5 main phases (planning phase, concept phase, embodies design phase and manufacturing phase, solution assessment). Additionally several references to the steps are made.

• A detailed table and describtion regarding the evaluationen is added applying the assessement criterias from L193-189.

• The actual orientation is 49° to the build plate. The 45° are changed towards a “tilted” orientation and an explanation regarding the 49° are added. At first 45° was set as a orientation but analysis of support structure and the laser path lead to an increase to 49°. Additional, experience form the machine operater recommended an increase of the angle to increase surface quality. The angle is a compromise of amount of support strcuture, surface quality, part geometry resolution and build height. In depth analysis between 45° and 55° were carried out.

•  Yes, this i spart of future and an additional sentence was introduced in chapter 5 “Summary and outlook”. A suitable test bench measuring pressure drop and flow rate has to be designed.

• A statement regarding the manufacturing costs in included. Those can be quantified easily whereas the other factors as “gain of AM experience” cannot be quantified in a same manner due to the incompatibility of the factors. However, an overall evaluation of the Knorr-Bremse working group is added which rank the overall AM experience gain and set-up of the digital process chain as a success.

• Yes, evaluating the AM costs is already feasible in the design stage after comparison of the build orientations with an AM cost model. A remark regarding early cost prediction is added in the evaluation of the concepts including a source for an AM cost model. This was not done for this specific part since the overall approach of the case company was to engage with the engineering team (from design to finishing) in AM technology and demonstrate the design process.

Reviewer 2 Report

The paper present a workflow design for additive manufacturing in order to produce parts designed for the production process.

The paper is well written an can be published with minor revision:

Line 356 to 359. Did you mean 49° orientation or 45° because it is named different between the lines.

Table 6. You talk about significant higher coast of the AM manufactured part. Please give a number for that i.e. 30 to 40% higher costs. Else it could also be 100 times higher costs which would make the design worthless.  

Author Response

Thank you very much for the detailed review and the interest in the presented work. All suggestions and comments of the review have been considered. Improvements were made in the areas mentioned:

• The paragraph was changed and specified. At first a tilted orientation was chosen and in depth analysis lead to a 49° angle mainly due to increased surface quality and manufacturing constraints.

• A value for the increase in manufacturing costs is added in the text. AM costs from an external supplier are more than 5 times higher than serial production. However, for prototyping and low-running special application the costs are competitive. The overall success is rated by the case company in engaging with AM design and the corresponding digital workflow.

Reviewer 3 Report

There is not much to comment on the paper. The structure and design is good. The applicability if the additive manufacturing methods to the presented case has been documented. The common knowledge about the superiority of the additive manufacturing in some cases has been confirmed. I can't really see the original idea here, but rather the documentation of a design case. Some data might be included like for example manufacturing cost. However the overall quality of the paper is fine.

Author Response

Thank you very much for the detailed review and the interest in the presented work.

• A value for the increase in manufacturing costs is added in the text. AM costs from an external supplier are more than 5 times higher than serial production. However, for prototyping and low-running special application the costs are competitive. The overall success is rated by the case company in engaging with AM design and the corresponding digital workflow.