Rounded Edge End Mills: Rounded edges on the tips of the flutes reduce chipping and lengthen the life of the tool. Also known as corner radius end mills, they work well for making molds. Use on cast iron, cast steel, and heat-treated steel. Sometimes called Bull Nose End Mills. Corner radius end mills feature a radius at the corner edge of the mill. Radii is incorporated for two primary reasons:
1) Extend tool life by increasing corner edge strength
2) Produce a desired radius in the part to meet functional print requirements.