Analysis of surface deformation under static and ultrasonic compression of aluminium

• Main Authors: Md. Daud, Mohd. Yusof, Lucas, Margaret, Jamaludin, Khairur Rijal, Anis, Samsol Faizal
• Format: Conference or Workshop Item
• Language: English
• Published: SIRIM 2010
• Subjects: QC Physics; TJ Mechanical engineering and machinery; TN Mining engineering. Metallurgy
• Online Access: http://eprints.utm.my/id/eprint/11799/3/YusofDaud2010_AnalysisOfSurfaceDeformationUnderStatic.pdf; http://eprints.utm.my/id/eprint/11799/; http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:101189

The quantitative assessment of the topographic features of surfaces is important for interpreting a wide variety of problems in surface contact. The mechanism of friction depends on the nature of the real contact between die and specimen interface and also upon the distributions, sizes and shapes of the asperities. Measurement of these features provides an essential insight into the contact friction. In this present study, the ring aluminium specimens were initially compressed under static upsetting, longitudinal ultrasonic (LU) and radial ultrasonic (RU) vibration applied on the lower die. Five different lubrication conditions were appiled to investigate the effects of friction in the ring compression test: dry surface, chemically pure oleic acid, Lubrodal, Molyslip, and a thin soft solid film of PTFE (polytetrafluoroethylene). This ring test was purposely carried out in our previous work to estimate the coefficient of friction between die and specimen. Subsequently the surface texture of the deformed aluminium ring specimens was assessed by a roughness measurement and topographic evaluation. To evaluate the surface, two common surface evaluation procedures were carried out; (1) Surface roughness measurement using a 2D-profilometer and, (2) surface topographic imaging using scanning electron microscopy (SEM). It was expected that these measurement could provide some further evidence or explanations of the coefficients of friction measured in the LU and RU ring tests. It was observed that the roughness of each surface has been well correlated with its surface texture. Generally, for all compression methods, a smoother surface was achieved by using dry and liquid lubricants and a rougher surface was presented by using Molyslip and PTFE. The application of the ultrasonic excitation during a compression test was effectively to reduce the surface roughness for dry and liquid lubricants. However for the surfaces that were coated with Molyslip and soft solid film of PTFE, the LU and RU loadings created an uneven surface texture. Keywords: Surface analysis, SEM, Ultrasonic compression, Ring test, Friction