Design and Optimization of Production Line Layout Using Material Flows
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Overall a good case study application of sound Line Balancing, Material Flow, and Industrial Layout Design techniques.
No new methods or techniques were presented, so the focus is as a case study paper.
Assembly Line Techniques are very basic and appropriate to this very simple three resource problem. Typically, downtime of equipment, or quality issues with equipment (hence OEE metrics) would also play significantly in a purchase decision, but the paper focused on capacity only. It would be advisable to include references to OEE metrics when addressing equipment (versus man) dependent throughput factors. A stacked bar chart (perhaps even Yamazumi chart) can be a helpful visual for these problems.
Changeover events were also mentioned in the paper and often, reducing changeover time (i.e. 3 hours) can be a big opportunity for increasing system throughput. Perhaps some machine replacement decisions involve reducing changeover time. (i.e. quicker and easier to clean equipment).
Flow Analysis for handling is good, however only distance and frequency to determine total travel distance per time are presented. In cases like this (dense production with unique materials handling challenges) it is often appropriate to determine transport time in addition to distance. In computing transport time, we consider slowing down for turns and the handling times for load, unload, reposition, scan, etc. at the beginning and end of each travel. We also consider slowing down on congested aisles to account for the width and traffic flow (something you don't see on a distance-only calculation). This approach can drive trips with longer distance and yet shorter delivery times.
Finally, the types of equipment were not adequately presented. It would be good to evaluate if trips by hand, walking, carts, conveyors or fork trucks were properly selected relative to what is the most efficient means to move each material. The paper did discuss these points but a chart or table on move-method considerations/alternatives would be helpful. This is especially important when a different move method could reduce floor space and/or handling requirements.
Another consideration is the removal of dunnage (i.e. old boxes and packaging materials) which can happen on return trips. It is good that return trips were mentioned, but it was not clear if any return trips could be used to reduce overall travel time (i.e. increasing device effectiveness). Effectiveness is often defined as the distance traveled with loads divided by distance traveled total (loaded and empty). In cases like yours, it is possible that travel time differences between alternatives are much closer than travel distances. This drives more effort on improving handling and straight-flow paths and containerization enhancements which reduce indirect handling labor.
Author Response
Thank you for your valuable comments. It would certainly be appropriate to focus on all the issues you mention,but unfortunately due to time constraints, we do not have time to incorporate it into this article. In any case, we plan to continue to focus on this problem and possibly use it in the next article.
But we have added some of your comments to the article. Specifically, material movement and movement methods (see lines 629-645) together with Figure 18 showing the handover point.
Thank you once again for your recommendations for further research in the future.
With warmest wishes and best regards.
Reviewer 2 Report
Comments and Suggestions for Authors
- The introduction must be more concise and provide sufficient background information on the research problem.
- The title is about the optimization design of the production line layout. However, the optimization strategies and their corresponding algorithms should be highlighted in this paper.
- Furthermore, the comparison between the newly constructed production line layout and the old one needs to be discussed in detail, and the results of this comparison require further elaboration.
Comments on the Quality of English Language
Moderate editing of English language required
Author Response
Thank you for your valuable comments. The comments were processed into an article. We expanded the Introduction to make it more concise and at the same time emphasize optimization strategies here (see lines 55-72). Furthermore, a comparison between the constructed production line layout and the old one was described and elaborated in detail (see lines 602-622).
With warmest wishes and best regards.
Reviewer 3 Report
Comments and Suggestions for Authors
- Clearly articulate how uncertainty in input parameters propagates through the analysis and affects key performance indicators (KPIs) such as production capacity, efficiency, and cost.
- Utilize techniques such as Monte Carlo simulation to simulate multiple scenarios considering the uncertainty in input variables and assess their impact on the proposed layout design.
- Provide probabilistic distributions for input parameters rather than deterministic values to capture the variability and propagate uncertainty more accurately.
- Analyze the robustness of the proposed layout design by evaluating its performance across a range of uncertain conditions and identifying strategies to mitigate adverse effects.
- Well done!
Author Response
Thank you for your valuable comments on a more detailed analysis of the given problem. Unfortunately, due to the time-consuming nature of the individual techniques, analyzes and simulations, we do not have time to incorporate them into this article. In any case, we plan to continue to focus on this problem and possibly use it in the next article.
We have at least included a closer analysis of the production capacity in the article (see lines 653-655). But for the inclusion of uncertainty and its influence on key indicators using various simulation methods and creating scenarios, we would need more time, and after elaboration, this treatment would certainly fill another article with its content. Also, some data (e.g. related to costs, etc.) the company does not wish to publish, but were actually taken into account.
Thank you once again for your recommendations for further research in the future.
With warmest wishes and best regards.
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
The revised manuscript has made a partial response to my suggestions, leading to a certain enhancement in the quality of the paper.
Comments on the Quality of English Language
The English quality is acceptable.
Reviewer 3 Report
Comments and Suggestions for Authors
well done.
