The effect of vibration amplitude on the surface roughness parameter

Abstract

Surface roughness is a set of surface irregularities with relatively small steps on the base length; it is measured in micrometers (mkm). Roughness relates to the microgeometry of a solid body and determines its most important operational properties. They are, first of all, wear resistance from abrasion, strength, density (tightness) of compounds, chemical resistance, appearance. The quality parameters of machine tool products must be measured at any change in the operation mode of the machine-tool; they must be statistically effective, i.e. measured with the greatest accuracy, thus making it possible to minimize the duplication of experiments; to be as informative as possible; to have a physical meaning. Machining cutting plates is not an exception in this aspect. The quality of the treated surface directly depends on the quality of the preparation of the cutting plates. Vibroabrasive processing can result in such quality. And one of the indicators of the quality of the treated surface is roughness. In order to demonstrate the correctness of the selected method, square plates made of Borsinit ceramics, NC 38-40 GPA hardness and cylindrical samples made of Composite 05IT ceramics, NC 18-20 hardness were used as samples. As a working medium, suspensions with mono-corundum powder with FEPA F100 grain, ultradispersed diamond powder UDM, micro powder of AFM diamond 20/14 and grinding powder of AC6 100/80 diamond at a concentration of 15% were used. The level of roughness of the workpiece surface at treatment is determined from a number of factors. The mode, speed and type of treatment, have influence on burrs height, on their form and location. Roughness depends also on the structure of material, its chemical composition, on the cutting instrument design and firmness, the level of its cooling, greasing. All these factors are united in three groups. The first group is related to the vibration of the cutting instrument at treatment, the second is related to the geometry and angle of cut, the third group is related to the level of deformation arising in the processed material. During work both the abrasive instrument and the processed workpiece and the machine-tool are subjected to vibrations. They are caused by the feed of the cutting tool, change in cutting speed or terms of friction. All the troubles in the machine-tool may result in vibrations, therefore high-quality hard fixing of all of auxiliary parts of the machine-tool is extremely important. Machine-tool vibrations are especially important at thin diamond treatment. Allowance at thin boring is uneven, the vibrations at cutting are high; it may result in technological vibrations. The vibration of a cutting blade influences roughness most of all at any type of work. Roughness grows with the increase of vibrations amplitude