Roughness and Hardness of 60/40 Cu-Zn Alloy
— The functional performance of machined components, often, depends on surface topography, hardness, nature of stress and strain induced on the surface, etc. Invariably, surfaces of metallic components obtained by turning, milling, etc., consist of irregularities such as machining marks are responsible for the above. Surface finishing/coating processes used to produce improved surface quality/textures are classified as chip-removal and chip-less processes. Burnishing is chip-less cold working process carried out to improve surface finish, hardness and resistance to fatigue and corrosion; not obtainable by other surface coating and surface treatment processes. It is a very simple, but effective method which improves surface characteristics and is reported to introduce compressive stresses. micro-irregularities start moving in the direction of the newly formed surface. The grain structure is condensed, producing a smoother and harder surface with superior load-carrying and wear-resistant capabilities. 2 + 0.0525X 4 + 0.0125X 1 X 4 − 0.02X X 4 − 0.0375X 3 X 4 Hv=160.625 − 2.37 5X 1 + 5.125X 2 + 1.875X 3 + 4.375X 4 − 1.625X 1 X 4 + 4.375X 2 X 4 − 2.375X 3 X 4 High surface microhardness (175H V ) was obtained at 400rpm, 2passes, 0.05mm/rev and 15kgf., and high surface finish (0.20µm) was achieved at 30kgf, 0.1mm/rev, 112rpm and single pass. In other words, surface finish improved by 350% and microhardness improved by 21% compared to as machined conditions.
EFFECT OF BALL BURNISHING PARAMETERS ON SURFACE ROUGHNESS USING SURFACE ROUGHNESS METHODOLOGY
Burnishing, a plastic deformation process, can be used to finish surfaces by plastic deformation of surface irregularities. A simple inexpensive and newly designed balburnishing tool, with interchangeable adapter for using different ball diameters, was used throughout the experimental work. In present paper reports on the optimization of the surface finish produced by ball burnishing process, using the surface response (RMS) methodology. A second order mathematical model correlating four predominant process parameters, viz, burnishing force, speed, ball diameter and number of tool pass, with the surface roughness parameter has been obtained. The model can be used in selecting the optimum process parameters for obtaining a desired control surface finish.
Investigations on the surface roughness produced by ball burnishing
Abstract Burnishing, a plastic deformation process, can be used to finish surfaces. Experimental work was conducted on a vertical machining centre to establish the effects of various ball burnishing parameters: depth of penetration, feed, ball material, burnishing speed and lubricant, on the surface roughness of AISI 1045 specimens. The ball materials used were WC and SUJ2. It was found that all the parameters studied affect the surface finish to varying degrees. The surface roughness parameter Rtm first decreases and then increases with increasing depth of penetration. The effects of feed and burnishing forces on the surface finish also showed similar trends. The effect of speed depends on the type of lubricant used. Grease is a better lubricant than cutting oil for the speed range of 450 mm min−1 to 1200 mm min−1. With appropriate selection of the process parameters, a pre-machined surface roughness of about 4 μm can be finished to approximately 0.7 μm.