Aluminium Burnishing Drill

A Burnish Drill is a drill with two cutting edges and two burnishing pads for drilling in aluminium accurately(hole tolerance H8-H9) with a good surface finish(1.6Ra)
Because of the burnishing pads which act as guide, the burnish drill has a rubbing action in drilling. Consequently, this is recommended at lower cutting speeds like 60-80 m/min; today these drills are mostly used on drilling SPMs.
On modern machining centres, the burnish drills with modified point geometry is also used for deeper holes >L/D 7 in aluminium. In such cases , they are also called Twin Lip Gun Drills.