This is the same insert as RT212, except it has a 1/32" (1.6 mm) radius. This larger radius insert will give a smoother finish when sleeve cutting to allow easier sleeve fitting and closer metal to metal contact for heat transfer. The 1/32" (1.6 mm) radius is stronger than the 1/64 (.8 mm) radius of the RT321. The RT322 should always be used for sleeve cuts unless the finish part requires the smaller radius for clearance or you are cutting a long bore. The larger radius creates more tool pressure than the small tool radius. The increased tool pressure will create chatter in the finish. A feed rate of .006" - .012" (.15 mm - .3 mm) per revolution should be used to obtain a typical surface finish. When machining large counter bores typically found in Cummins or Cat Blocks, a feed rate of .002" - .004"/rev. (.05 mm -. 1 mm/rev) should be used. When cutting gray cast iron use a speed in the 800 – 1200 S.F.P.M. area for best productivity and tool life.
When cutting nodular, ductile, or compacted graphite cast iron the speed should be in the 200 – 400 S.F.P.M. area – 300 RPM on a 4" (100 mm) diameter bore. Nodular, ductile, or compacted graphite cast iron is found most often in high performance engine blocks or sleeves. When cutting these tuff cast irons it is best to use a feed rate of between .006" and .010" (.15 mm and .25 mm) per revolution.
