Review Reports

Round 1

Reviewer 1 Report

This article included the surface contact in DEM model and compared the simulation with their experimental results. The authors got the contact parameters, the static-friction coefficient and restitution coefficients, from experiments. Surface roughness reduction by simulation were compared with the experimental results. While the authors named the title as “Prediction of roughness reduction in centrifugal disc finishing of additive manufactured parts based on Discrete-Element-Method”, too limited paragraphs were made on the DEM. Adding more paragraphs for DEM, perhaps the general discussion and/or the governing equations with the contact force component terms, can help relating the article contents to the title. Or, the authors can change their title to better fit the contents. Another major issue is about the modulation of the normal-stiffness coefficient. Setting f_k=1e-3 seems to suggest that the stiffness coefficient can simply ignored. Saving computational time is not a good reason for this modulation but the little contribution of k_n is. One minor problem is the mistakes on the citation—a comma must be added between two cited reference numbers.

Author Response

Thank you for reviewing the manuscript. Revisions in the manuscript based on your comments are highlighted in light-blue.

 “[…] too limited paragraphs were made on the DEM. Adding more paragraphs for DEM, perhaps the general discussion and/or the governing equations with the contact force component terms, can help relating the article contents to the title.”

• In addition to the governing equations for the contact force and timestep calculation (section 2.4.2) a schematic figure of the DEM calculation cycle was added in the introduction (Figure 1).

“Another major issue is about the modulation of the normal-stiffness coefficient. Setting f_k=1e-3 seems to suggest that the stiffness coefficient can simply ignored. Saving computational time is not a good reason for this modulation but the little contribution of k_n is.”

• As shown in Figure 8a, reducing the normal stiffness coefficient kn by a factor of fk = 10-3 reduces the contact forces, which does not mean, that the normal stiffness coefficient kn can be ignored. Simulations of normal contact forces Fc,n with a reduced normal stiffness coefficient kn still reflect the influence of the rotation speed and the media type as shown in Figure 8b.

“One minor problem is the mistakes on the citation—a comma must be added between two cited reference numbers.”

• Done
  

Author Response File: Author Response.pdf

Reviewer 2 Report

Prediction of the roughness reduction in centrifugal disc finishing of additive manufactured parts based on Discrete-Element-Method Review points

 

Abstract

1.       Abstract is missing the objective and scope of the work; it is advised to rewrite by focusing on the main aim of the work.

Keywords

2.       What is mass finishing?

Introduction

3.       Authors mostly concentrated on DEM and its applications for prediction in the introduction, but it is suggested to write some information about the roughness and its importance.

4.       Authors used mostly outdated references to cite, and it is advised to use some recently published articles to describe the necessity of conducting research on centrifugal disc 2
finishing of additive manufactured parts

5.       It is also suggested to write the objective and scope of the last paragraph of the introduction.

Author Response

Thank you for reviewing the manuscript. Revisions in the manuscript based on your comments are highlighted in yellow.

Abstract

1. Abstract is missing the objective and scope of the work; it is advised to rewrite by focusing on the main aim of the work.

The abstract was rewritten and is focused on the aim and the scope of the work now.

Keywords

2. What is mass finishing?

Mass finishing is a common term for machining processes, in which a bulk of abrasive media is used as tools. Mass finishing includes processes such as vibratory finishing, centrifugal disc finishing, barrell finishing and drag finishing. The main goal of mass finshing processes is the roughness reduction and polishing but also edge rounding and deburring. A good overview of mass finishing processes is presented in the following article:

Hashimoto, Fukuo; Yamaguchi, Hitomi; Krajnik, Peter; Wegener, Konrad; Chaudhari, Rahul; Hoffmeister, Hans-Werner; Kuster, Friedrich (2016): Abrasive fine-finishing technology. In: CIRP Annals 65 (2), S. 597–620. DOI: 10.1016/j.cirp.2016.06.003.

Introduction

3. Authors mostly concentrated on DEM and its applications for prediction in the introduction, but it is suggested to write some information about the roughness and its importance.

The importance of the surface roughness for the fatigue life and wear resistance of additive manufactured workpieces was included in the abstract as well as in the introduction of the manuscript. Recent literatur dealing with the relationship between the surface roughness and mechanical as well as tribilogical properties were included

4. Authors used mostly outdated references to cite, and it is advised to use some recently published articles to describe the necessity of conducting research on centrifugal disc 2 finishing of additive manufactured parts

The necessity of conducting research on centrifugal disc finishing was clarified in the introduction. The main issue of centrifugal disc finishing is the lack of controllability as workpieces are machined in a freely movable manner. Thus, compared to the widly used drag finishing, finishing results are hardly predictable. Consequently there is a need for a prediction model. Recent literatur dealing with drag finishing was added.

5. It is also suggested to write the objective and scope of the last paragraph of the introduction.

Acutualy there is a paragraph at the end of the introduction in which the aim and the scope of the work is presented. A blank line has been added at the end of the introduction to highlight this paragraph.

Author Response File: Author Response.pdf