TurningMillingDrillingTechnicalInformationIndex Chip breaker overview General turning Negative inserts Roughing A DR double sided P K Double sided chip breaker with positive rake angle and stable cutting edge for light to medium roughing of steel and cast iron. DR single sided P K B Single sided chipbreaker with positive rake angle and stable cutting edge for light to medium roughing of steel and cast iron. LR P M C Single sided chip breaker with curved cutting edge and unique bumpy geometry. Low cutting pressure for process reliable machining. Light roughing of steel and stainless steel. ER double sided M S D Double sided chip breaker with large rake angle for low cutting forces. Suitable for roughing of stainless steel. ER single sided M S Single sided chip breaker with large rake angle for low cutting forces. Suitable for roughing of stainless steel. E A 19