mm decreasing zone ii travelling speed v 10 0 m min constant feed a 3 mm constant zone iii travelling speed v 10 0 to 12 m min increasing feed a 3 mm to 6 mm increasing ______________________________________ ______________________________________zone i travelling speed v 10 0 m min constant feed a 8 mm to 5 mm decreasing zone ii travelling speed v 9 0 m min constant feed a 6 mm constant zone iii travelling speed v 8 m min to 12 m min increasing in eight steps 0 5 m min each feed a 6 mm constant ______________________________________ the feed a is gradually reduced in zone i from 8 mm to 5 mm the lowest feed a of 5 mm is not equal to the feed a predetermined for the zone ii rather in zone ii an increased feed a of 6 mm is held constant the thus increased output quantities are compensated for by a reduced travelling speed v of 9 m min ______________________________________zone i travelling speed v 10 0 m min constant feed a 8 mm to 5 mm decreasing zone ii travelling speed v 10 0 m min constant feed a 6 mm and 4 mm alternating zone iii travelling speed v 8 m min to 12 m min increasing in eight.