Study of Parameters Affecting the Skinning Process of Palm Midribs

Abstract

The efficient use of residues of the date palms, especially the midribs as local alternative resources for wood, will have a great impact on the economy of Egypt. The skinning of date palm leaves’ midribs has been proved to be an appropriate technology for their processing for Egypt economically and socially. The skinning process is defined as the removal of the outer layers of the midrib, using several cutting tools or multi-edge cutting tool with pre-determined conditions for tool, workpiece, and process. A test rig machine has been designed and executed to investigate the skinning mechanism, the effects of the clearance angle, tool angle, inclination angle, the skinning speed, and the layer thickness, on the specific skinning force (skinning force per unit width) and the surface roughness. Preliminary experiments have been carried out to eliminate the unsuitable values of tool material and specimen orientation. The experiments have been planned to be carried out on levels, First, the skinning speed and the layer thickness have been studied together using the minimum wedge angle and large clearance angle, and 0° inclination angle conditions, to investigate the skinning mechanism changes and effect of these factors on the specific skinning force. Thereafter, effect of the clearance angle has been introduced in study of these two variables. Appropriate value of the clearance angle, layer thickness, and skinning speed have been selected to study effect of the tool angle on the specific skinning force. At the end, effect of the inclination angle has been investigated with selected values of layer thickness, skinning speed, clearance angle, and tool angle. Three repetitions of the same condition have been carried out, in which the same condition has been performed for different specimens (the same condition has been repeated three times for the same specimen for the preliminary experiments) to consider the variations between the specimens to represent the skinning correctly. The skinning is the process of the removal of a continuous rigid layer by splitting from the specimen. The skinning mechanism, split-type layer formation, is similar to that of wood cutting. Skinning starts with the formation of initial crack by the skinning tool. The crack propagates as the tool moves to accomplish skinning of the whole specimen. The crack length varies within the specimen, indicating the variation of the material strength within the specimen. The crack length increases by the increasing the layer thickness. The crack length during the skinning of palm midribs is longer than that dur