Tapping in Ductile Iron

A while back, we ran into a situation where a customer was tapping cast iron on a flange. There were 2 tap sizes M-16 x 2.0mm coolant thru tap as well as M20 x 2.5mm coolant thru tap. There were 6 holes to be tapped in the part. We were able to double the RPMs from 2300 to 4600 thus cutting the cycle time in half. Our customer also reported to us that they got 90 parts for tool life versus the 30 parts with a German competitor tap. Obviously, they were very pleased.