Journal of Agricultural Machinery
with the collaboration of Iranian Society of Mechanical Engineers (ISME)

Performance Analysis of a Walnut Peeler with a Rotating Cutting Plate

Document Type : Research Article

Authors

H. Samimi Akhijahani 1
M. S. Barghi Jahromi 2

1 Department of Bio Systems Engineering, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran

2 Department of Mechanical Engineering, University of Jiroft, Jiroft, Iran

https://doi.org/10.22067/jam.2025.90199.1294
Abstract
Introduction
Walnut (Juglans regia L.) is a highly valued horticultural product, and significant efforts are underway to enhance its production in Iran. Despite the development of various tools aimed at increasing productivity and improving harvesting efficiency, over 90% of walnuts in Iran are still harvested manually, often with the aid of specialized tools or by striking the trees with sticks. Although numerous mechanical devices have been introduced, the considerable height of walnut trees and the asynchronous ripening of the nuts continue to make traditional harvesting methods predominant. In this research, a novel walnut peeling system incorporating a horizontally rotating cutting plate was developed and evaluated. The cutting plate, designed with specific grooves and curvature, aims to enhance the mechanical efficiency of the peeling process. This analysis investigates the influence of rotational speed and groove depth on system performance. In addition, the life cycle assessment is conducted to evaluate the environmental and operational impacts of the proposed system, with comparative analysis against conventional peeling methods.
Materials and Methods
The designed and constructed system consists of three main parts: the container, the rotating disk, and the power system, which includes the electric motor. The rotating disk, as the heart of the system, is made from a 1.5 mm thick steel sheet with a diameter of 640 mm. It has been laser-cut with sufficient precision to cut and transfer walnuts. The third part of the system is the power unit, which includes a 3-hp, 1400 rpm electric motor. Power transmission is carried out using a V-shaped belt. In this system, the product is first collected from the designated garden and stored in equally weighted bags. The rotating plate is the most important component of the walnut peeler, essentially the heart of the system. On this plate, there are 12 oval grooves, each 5 mm in diameter and 150 mm in length. One side of each groove is raised, with a depth that can be varied. Increasing the groove depth increases the amount of peel removed and exposes a larger surface of the walnut. The plate is connected to the driven pulley and then to the electric motor via a shaft. In this research, a life cycle assessment was also used to evaluate the impact of various parameters of the walnut peeling system on the environment and its pollution level.
Results and Discussion
The findings from the variance analysis regarding the impact of groove depth and rotation speed on peeling percentage indicate that variations in plate groove depth and electric motor rotation speed during walnut peeling are significant at the 1% level. Furthermore, the impact of changes in the groove depth of the cutting plate on machine performance and the reduction of walnut losses is substantial, showing significance at the 1% probability level. The effect of this factor on the amount of damage to walnuts is significant at the 5% level. By increasing the groove depth from 1.5 to 3 mm and from 3 to 5 mm, changes of 6.99% and 5.12% in walnut skin removal were observed. By reducing the elevation of the groove, the amount of cutting removed from the walnut surface is also reduced, and the peeling process becomes more abrasive. In this case, for proper peeling, the cycle duration and retention time in the machine should be increased. By increasing the rotational speed from 218 to 275 rpm, the momentum and linear velocity increase, resulting in more green shell removal. Conversely, reducing the rotational speed decreases the impact, leaving more green skin on the product. The interaction between rotational speed and groove depth is also significant in the amount of peeled product at the 1% level. The results of the life cycle assessment showed that the human health index has the highest value due to the use of electric power, iron profile (in the system chassis and container), and copper wire in the electric motor armature. Optimizing the system and using clean energy can help improve system efficiency and reduce environmental impact.
Conclusion
Utilizing a walnut peeling machine achieves an impressive 94% efficiency in walnut peeling while ensuring less than 5% damage. The results of the life cycle assessment showed that the use of a walnut peeling machine has less environmental damage than the traditional method and is highly cost-effective.

Keywords

Damage
Life cycle assessment
Effective productivity
Rotary cutting plate
Walnut quality
Subjects

Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)

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  • Receive Date 10 October 2024
  • Revise Date 21 December 2024
  • Accept Date 12 January 2025
  • First Publish Date 07 June 2025

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