Design, Construction, and Performance Evaluation of a Conical Hazelnuts Cracker Machine

Document Type : Research Paper


1 Department of Agro-technology Engineering,, Aburaihan Campus, University of Tehran, Tehran, Iran

2 Teacher and supervisor of the machine tool workshop, Shahid Chamran Technical High School, Qazvin


In this research, to breaking the hard woody shell of hazelnuts to obtain the whole and health kernels the conical hazelnut cracker prototype machine with the vertical shaft was designed, constructed, and evaluated. Calculations of the design and manufacturing this machine were performed based on data on the physical and mechanical properties of hazelnuts. The working principle used for this process was based on two coaxial conical shells, which the external shell was fixed on the chassis, and the internal shell named rotor was driven by a vertical shaft. The hazelnut kernels in the space between the two cones in the active area of fracture are affected by the compressive and shear forces and the wood shell is broken and the kernel is removed healthy. Performance evaluation of machine was conducted as a factorial experiment in the form of a CRD with three factors of the moisture content (MC) of hazelnuts in two levels of 5.0% and 8.5% wet basis, the size class (SC) of hazelnut in three levels of small (size < 14 mm), medium (14 mm ≤ size < 16 mm) and large (size ≥ 16 mm), and the rotor rotational speed (RRS) at three levels of 150, 200 and 250 rpm. Results showed that MC and SC have significantly effects on the percent of the intact kernel and the overall losses at the level of 1%, but the RRS had no significant effect on them. In general, the percentage of the intact hazelnuts at 5% and 8.5% MC were 86.1% and 92.1%, respectively. The performance of the hazelnut cracker machine in producing the intact kernel for the size classes of the small, medium, and large was 87.2%, 89.5%, and 90.6%, respectively.


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