Innovative optimization of feed and spindle speed levels for surface roughness and cylindricity tolerance of the drilled holes in liquid stir casted Al6061 hybrid composite reinforced with 15% weight fraction of SiC+Fly ash and comparing the above results. Journal of Pharmaceutical Negative Results. Published online September 27, 2022:413-427. doi:10.47750/pnr.2022.13.S04.046