It's not easy to drill ductile iron with cobalt high speed steel bit. Please help to point it out
The material can be annealed and the process is simple, that is, heating the workpiece and cooling it naturally. In this way, the hardness of the workpiece can be reduced.
Choose carbide or whole carbide drill, about 90HRC in hardness. But it requires a high number of drills, around 3000.
Determine the authentic M35 cobalt bit, which is about 65HRC in hardness. General workpiece hardness of about 45HRC or less of the problem.
