Study of Relationship of Mechanical Properties of Indian Wood Species with Cutting Forces and Surface Finish in Slot Milling using a High Speed 3-axis Vertical CNC Router System

Abstract

Wood is an important natural material and being used for various applications since ages. The larger percentage of the timber wood is used for furniture making as well as a construction material in addition to being used as an engineering material. The wood as an engineering material possess anisotropic properties and some time has random defects. During manual wood machining operations one can take care of anisotropic nature of wood properties as well as the random defects but it is obtained at the cost of a lot of time. The CNC machining of wood can help us save a lot of machining time while simultaneously offer better machining accuracy, but it is desired that the relationship of machining parameters to be selected and the desired machined properties of the wood samples be studied to explore the full potential of using CNC wood machining systems. The wood as an engineering material has several mechanical properties but those mechanical properties which directly influence the machinability of wood are required to be studied. In this thesis work the previously published literature has been studied in detail to identify the mechanical properties of wood which effect the machinability of wood. Further a systematic approach has been used to determine the values of these mechanical properties as per standard procedure available from the Bureau of Indian Standards as well as standard published standard procedures. The six Indian wood species are used in the present study where we have tried to establish a correlation between the mechanical properties of these wood species with the cutting forces observed in slot milling and the surface finish obtained in the bottom of the slotted cut. It has been observed that the wood grain orientation is a key factor for machinability of wood because different slot milling orientation gives different measurable output of surface finish and cutting forces. Procedures to find out different mechanical properties are discussed and their averaged values are considered for analysis. A high rpm 3-axis vertical CNC router is used in the present study for slot and plunge milling while a force dynamometer is used for recording the magnitude of cutting forces thus produced. A stylus type surface roughness tester was then used to measure surface roughness of various machined samples. The results of different mechanical properties, various cutting forces and surface finish are thus analysed to identify the relationship among them. The literature surveyed for the present study, the procedure followed for determining the values of various measurable parameters and hence observed results and discussions have been presented systematically in this thesis report.