Recently, the vertical machine has drawn a great deal of attention all over the world, in the fields of molding, automobiles and airplanes and so on. The main reason is that it has brought about remarkable accomplishments in reducing production time and cost. Besides, it shows satisfactory surface roughness in the quality of workpiece. The purpose of this study is to investigate the characteristics of surface roughness according to the feed rate by taking the spindle speed for a parameter in the cases of compression air, waters-soluble cutting oil and non water-soluble cutting oil.
Generally, the characteristics and precision of machined surface are known to be affected by the cutting force and cutting oil, which leads to a great many of researches conducted to predict the cutting force through machined profile models. Especially, the end-mill processing widely used in the field of processing is determined by the characteristics of machined surface such as the shape, precision and surface roughness of machined parts. In order to minimize the tolerance occurring during the process of end-milling aluminum 7075, mostly used for the parts and structure of an airplane, this study attempted to grasp the optimal cutting conditions by investigating what effects the characteristics of cutting oil, affecting the cutting condition and cut surface, have on the surface roughness. In addition, a comparative experiment was carried out to examine the change of surface roughness affected by several different cooling conditions, such as compression air, water-soluble cutting oil and non water-soluble cutting oil out of all the various cutting conditions during the process of processing with the vertical machine.
As a result, in all the cooling methods with compression air, water-soluble cutting oil and non water-soluble cutting oil, it was found that the more the spindle speed increases, the more the value of surface roughness decreases on the surface of machined objects, while the more the feed rate increases, the more the value of surface roughness increases on the surface of machined objects. Moreover, under the condition that the spindle speed was 500 ∼ 1400 rpm, it was found that the value of surface roughness was highest in the cooling method with compression air, while it was lowest in the cooling method with non water-soluble cutting oil. However, in both the cooling methods with compression air and water-soluble cutting oil, it was found that the surface roughness was almost same all over the sections of both the spindle speed and the feed rate.