Browsing by Author "Javaid, N."

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    Application of response surface methodology for the optimisation of micro friction surfacing process
    (Elsevier Science B.V., Amsterdam., 2010-08-15T00:00:00Z) Vitanov, V. I.; Javaid, N.; Stephenson, David J.
    The aim of this work is to identify relationships between the input variables and the process response and to develop predictive models that can be used in the design of new friction surfacing applications. Moreover to investigate the use of standard CNC machines for friction surfacing. The experimental design techniques and response surface methodology were used to investigate and select the combination of factor levels that produced the optimal response. The main effect of the velocity ratio obtained by dividing the feed rate of mechtrode with traverse rate of substrate was observed to be the most significant factor on the process response. Based on the results of optimisation it was observed that the lower to intermediate levels of rotational speed and intermediate to higher levels of velocity ratio produced good coating quality. (C) 2010 Elsevier B.V. All rights reserved.
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    Investigation of the thermal field in micro friction surfacing
    (Elsevier, 2010-05) Vitanov, V. I.; Javaid, N.
    To model the thermal response of the micro friction surfacing process with complex geometries and to tackle transient deposition processes, suitable numerical methods have been developed. The approach of coupled transient thermal analysis to account for the temperature fields generated during the dwell and deposition phases of the process resulted in reasonably accurate results, with an error of 18% between absolute maximums. The major discrepancy between the experimental and simulated results occurred at locations with a change in substrate geometry. The heat distribution profile at the frictional interface and variation in material properties with temperature could have significant effects on the thermal response.
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    Nano-level surface generation on H13 alloy steel by ultra-precision grinding with electrolytic in-process dressing
    (2010-09-16T00:00:00Z) Javaid, N.; Stephenson, David J.; Vitanov, V. I.; Vitanov, V. I.; Harrison, D.
    The aim of this work was to achieve the surface finish of 10nm on a 40mm diameter disc of chrome-molybdenum-vanadium alloyed steel (H13) by using precision grinding process with electrolytic in-process dressing. The machine tool utilized was Tetraform-C, its unique tetrahedral frame offered higher structural stability. A cup grinding wheel with iron bonded CBN abrasive grit of 76 microns average size with 50% concentration was used. The statistical methods were employed to determine the optimal combination of input parameters to achieve the required response. The main effect of feed rate was found to be more significant than the depth of cut and lower levels of these factors produced better surface finish. The developed regression model based on the relationships between process variables was used to predict factor levels to achieve the required process response.