The Effect of Forklift Type, Pallet Design, Entry Speed, and Top Load on the Horizontal Shock Impacts Exerted during the Interactions between Pallet and Forklift

Round 1

Reviewer 1 Report

This paper was focused on the optimal condition of forklift system after conducting various testing sequences, including forklift type, pallet design (material), entry speed, top load. May this study provide useful information for the designer of forklift system but those contribution cannot prove the required quality in Applied Sciences.

This study may be regarded as technical report for design engineers and it may be adequate for test-oriented technical journals.

I cannot find the originality of this study. In addition, I cannot agree with the evaluation of each test results via measured acceleration only. The dynamic response at certain location cannot support the severity of selected event or accumulated damage.

Under this circumstances, I am very negative for current version.

Author Response

Please find the answers attached.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is interesting, but it needs an improvement, because now it is a bit a technical report.

1. Please describe what is "shock impact", how it is understod by the authors and give the literature review on this phenomenon and methods of its testing.
2. What is innovative in this paper, aspecially improving the scientific backroud of the study?
3. Conclusions should be widen with the analysis of physical phenomena influencing the achieved results - not only the technical report of results.

Author Response

Please find the answers attached.

Author Response File: Author Response.docx

Reviewer 3 Report

1. What is your mean of “testing Sequence”? explain more on this.
2. In line 21 (abstract) what parameters exactly the authors mean of “Pallet design”? It is somewhat ambiguous.
3. In line 16 the purpose of the research was mentioned as the effect of various factors on shock response, while in the last sentence of the abstract the acceleration response of the forklift and the pallet was expressed as the results of the research. How will the authors explain this inconsistency?
4. How are the acceleration of forklift and pallet related to each other? Better to mention in the abstract.
5. In line 34, do you think is it possible to 100% ensure that the products will not be damaged during the shock or sudden drops? This sentence should be reviewed, and some other alternatives should be used instead “must ensure”.
6. In line 36, how loss tracking system can be helpful in cost-effective solutions? Are there any relations between costs and tracking systems? If so, better to mention here.
7. Fork tine damage was ranked as 4^th common type of damage in line 41, why the authors did not discuss other 3 most important factors and chose this?
8. Line 64 if there is a limited number of research effort on shock impacts, better to mention them here and discuss about the results.
9. In line 75 authors should explain what their exact purpose is of “excessively severe”.
10. In line 82 use is instead of “was”.
11. In this research work, the authors have used “shock transmissibility” and “vibration transmissibility”, do they want to convey the same concept?
12. In table 1 on page 3, why the power and type of motor has not been presented?
13. The axis direction is vague especially for y and z direction.
14. In line 147 why you changed the directions of x,y,z axes between b and c in Figure 3?
15. Line 155 what is the reason behind marking 0.22 m/s and 0.45? I mean why the authors selected them as entry speed?
16. Line 165 what is the purpose of term “replicate of combination”?
17. How did you obtain coefficient of variation equal to 37%?
18. In line 199 based on what criteria the authors concluded that the variation in the research is acceptable?
19. What do you mean 2-way and 3-way interactions? (Line 206 and 207)
20. In line 219 it has been mentioned that friction coefficient and stiffness of wood pallets are the main contributors to highest acceleration of wooden pallets rather than plastic pallets. As the weight of pallets also can be important factor in acceleration response, why this factor has not been considered?
21. In line 230, how the authors justify the reason why acceleration response raises 22% for the increase of top load from 680kg to 1134 kg, while only there is a small rise of 5 % when it increases from 227 kg to 680 kg?
22. At line 258, why the variation coefficient has not been calculated as 40%, but in line 261, the coefficient mentioned as 37%?
23. In line 262 why the English units (in/s) was used for speed while in whole paper SI unites utilised?
24. On page 10 line 268, why the behavioral pattern of peak acceleration response for top load changed?
25. Line 325 what is the exact purpose of inconsistence relation between top loads and the forklift types?
26. In table 6 why P-values are all zero? Also, the difference should be positive.
27. For comparison purposes it is better to draw z acceleration in same graph for forklift and pallet
28. In last paragraph of page 13, there is a discussion with the focus on previous study by Rodriguez. It is better to mention what is the state-of-the-art aspect of this study comparing to that one. Or are there any better results of recommendation which make it unique or not. If so better to add in this section and discuss.
29. In line 375 the reason of increase in acceleration response because of speed increase mentioned as kinetic energy response. Why there is no discussion about kinetic energy in the article?

Conclusion

In this research work, the effect of pallet design, top load, entry speed and forklift type on the acceleration response and shock response has been investigated. The comparisons between results are clear but there is not enough discussion on the main reasons behind the effect of different factors on shock response. Better to add more discussion on the results as well as expressing some state-of-the-art aspects to the work to make it appropriate to be published.

Author Response

Please find the answers attached.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The main focus of this study was to identify the sensitivity of acceleration responses in both forklift and pallets over different impact conditions, forklift type, pallet design, entry speed, and top load. The sensitivity of peak accelerations at both forklifts and pallets was well stated at result session but I still doubt the academic originality of this study as shown below.

[1] The behavior of response acceleration can sufficiently represent the severity of impact condition of forklift system? In addition, how can you ensure the behavior of both target system, fork lift system and pallet under the limited measurement positions?

[2] There is no dynamic analysis for target systems, both forklift system and lifting pallets, so that you cannot explain the reason of different acceleration results at conclusion. Just technical report cannot support your advances in academic job.   

[3] The acceleration data cannot show the maximum stress at the hot spots at interesting mechanical system. If you want to show the severity condition of impact event, you should explain them with several physical quantities.

[4] Which factor is most important one in equation (1)? There are no weighting factors at the evaluation of impact events. Is it acceptable?

My judgement is still “major revision” for the current one.  

Author Response

Comments & suggestions:

The main focus of this study was to identify the sensitivity of acceleration responses in both forklift and pallets over different impact conditions, forklift type, pallet design, entry speed, and top load. The sensitivity of peak accelerations at both forklifts and pallets was well stated at result session but I still doubt the academic originality of this study as shown below.

Re: The aim of our paper is to observe and analyze the physical environmental circumstances of unit loads at different conditions to help packaging engineers design more efficient unit load. The goal is not to characterize the intensity of impacts and not to analyze the fundamental mechanical interactions during impact. Currently, the lack of information on the impact intensities exerted by forklifts to the pallet, make it difficult for packaging engineers to evaluate the durability of the pallet and consequently to quantitatively improve pallet durability. The ISO 8611 testing standard that is used all over the world, does not even advises on an impact level that package testing lab professionals should even use due to our lack of understanding of the impact levels.

This research project was started due to the need to improve pallet testing standards and also financially supported by the pallet industry. Further supporting the need for this information.

The results of the research can have significant information input to the unit load and packaging design at the applied science field. It should also be mentioned in particular that no one has investigated these conditions so far, so the results are very novel, and the methods of analysis and measurement meets the literature requirements as stated by the other reviewers.

[1] The behavior of response acceleration can sufficiently represent the severity of impact condition of forklift system? In addition, how can you ensure the behavior of both target system, fork lift system and pallet under the limited measurement positions?

RE: During the study, the authors did not just collect data on the acceleration level but on the impact duration, and velocity change to completely characterize the shock event. All of these values are listed in Table 4 and Table 5. The authors decided to use the acceleration level and the shock duration during the discussion on the effect of the variables because these two values best represent the energy of the shock event. The only historical study that was similar to this work (Rodriguez et al. [22]) also used a similar approach.

[2] There is no dynamic analysis for target systems, both forklift system and lifting pallets, so that you cannot explain the reason of different acceleration results at conclusion. Just technical report cannot support your advances in academic job.  

RE: Conducting a dynamic analysis of the pallet and the forklift, is beyond the scope of this work due to the variations between the forklift types and pallet types. The goal was the quantify the level of impacts and understand which variables are affecting it intensity. The authors did this through a statistical analysis. This approach is heavily used in the packaging field especially to understand the level of truck vibration events.

[3] The acceleration data cannot show the maximum stress at the hot spots at interesting mechanical system. If you want to show the severity condition of impact event, you should explain them with several physical quantities.

RE: The authors like the reiterate that we did measure acceleration, duration, and velocity change and presented these values in the article. The we did not just rely on acceleration. This is a similar approach that is often presented in similar research studies.

The authors also want to point out that applicable ISTA and ASTM testing standard also only list the acceleration and duration to characterize the shock impact that needs to be exerted on the pallet during testing.

[4] Which factor is most important one in equation (1)? There are no weighting factors at the evaluation of impact events. Is it acceptable?

RE: Equation 1 presents the model for ANOVA and not a regression model where weighing factors would be relevant. The authors presented in throughout the document that the Pallet design and entry speed had the greatest effect on the response measured for the forklift. The goal was not understood which factor had the greatest influence on the results. Which the authors presented.

My judgement is still “major revision” for the current one.

Reviewer 2 Report

The authors considered all my comments. The paper can be published, in my opinion.

Author Response

The authors would like to thank you for your thorough review of the paper and your suggestions. Your comments helped us improve the quality of the paper. 

Round 3

Reviewer 1 Report

As authors stated, it may be helpful for packaging engineers to provide unit impact conditions over different suggested conditions whose background data were not well found in literature. However, the unit impact conditions must be related to the dynamics of forklift system so that the prepared service conditions in this paper cannot sufficiently support your results and I still accept your rebuttals even for second review.

I suggested you should remark such limitation in the abstract.

The severity of unit impact action was not directly related to ‘damage’ of your target systems because no damage analysis was conducted using the measured data.

My judgement is neutral (not positive).

Author Response

The authors appreciate the comment from the reviewer and want to express their appreciation for the insight and helpful remark that made the paper more complete and better. Based on the comment we have added a limitation section before the conclusions and also included a limitation in the abstract. The authors hope that the additional limitation section fully addresses the reviewer's concerns.