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EDM of aluminum alloy 6061 using graphite electrode using paraffin oil and distilled water as dielectric medium

Imran M., Rahmanshah S. M., Mehmood S., Arshad R.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 3

72--79

EN

EDM machining of Al 6061 was performed under varying conditions of pulse current and pulse duration. Graphite was used as an electrode material with distilled water and paraffin oil as two different dielectric mediums. The aim is to characterize the surface integrity produced as a result of EDM machining under both varying electrical and non-electrical parameters as it is important in determining the service life of EDM machined components. The vertical, horizontal and corner surfaces are studied independently for each single set of conditions. The average white layer thickness (AWLT) and surface roughness was found to be dependent on pulse current values and pulse duration. The dielectric medium also has an influence on the thickness and nature of white layer. It was found that the thickness and nature of the white layer formed from distilled water is different from that of paraffin oil. New methods of AWLT and surface roughness measurement through an optical microscope are described. The surface roughness method developed was calibrated against an identical surface roughness tester. Finally, material removal rate, tool wear rate, the presence of micro cracks, voids and globules were compared for different conditions and conclusions were drawn according to the actual physical conditions during machining.

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Determination of residual stress distribution in high strength aluminum alloy after EDM

Mehmood S., Sultan A., Anjum N. A., Anwar W., Butt Z.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 1

29--35

EN

Thermal energy produced by discrete and random electric sparks in electric discharge machining (EDM) melts surface material. A portion of this molten material is removed and the remaining material resolidified by rapid cooling in a hydrocarbon oil. The effect of repeated heating and cooling of the surface and sub surface material with complex temperature gradients results in residual stresses in machined parts. The aim of this investigation is to determine the distribution of residual stresses in the depth of machined material with respect to discharge current, most important electric parameter during EDM. It is well known that surface finish is dependent on discharge current. Therefore, investigations were carried out for smaller discharge current levels i.e. 3, 6, 9, 12 ampere. Hole-drill strain gauge method is used for the determination of residual stresses in the depth of material. For comparison purposes, residual stresses are also determined for conventionally turned specimens. This study provided quantitative analysis of the residual stresses for various discharge current in EDM which is a key parameter in deciding the service life of material.

3

Lipoxygenase Inhibitory Lignans from Salvia santolinifolia

Mehmood S., Riaz N., Ahmad Z., Afza N., Malik A.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 3

571-575

EN

Santolinol, a new lignan has been isolated from the chloroform soluble fraction of Salvia santolinifolia and as signed the structure 1 on the basis of spectral studies including 2D NMR. In addition three bifuranolignans namely didemethylpinoresinol 2, (+) fraxiresinol 3 and (+) 1-hydroxysyringaresinol 4 have also been isolated for the first time from this species. All these compounds showed potent inhibitory potential against the enzyme lipoxygenase.

4

Butyrylcholinesterase Inhibitory Triterpenes from Salsola baryosma

Ahmad Z., Mehmood S., Ifzal R., Malik A., Afza N., Rashid F., Mahmood A., Iqbal L.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 8

1427-1432

EN

Salsolic acid (1), a new oleanane type triterpene has been isolated from the chloroform soluble fraction of Salsola baryosmaalong with known triterpenes (2) and (3) isolated for the first time from this species. The compounds 1–3 showed inhibitory activity against the enzyme butyrylcholinesterase.