Parkway Machine is a job shop specializing in the rebuild of gas compressors for the oilfield business.  One job that comes in often is the thread repair of TAH Fluid Blocks.  4” Diameter, 4 Pitch Full Acme, 4” Deep in a steel fluid block housing is typical.  Parkway Machine had typically welded the bore to build up material, and then bored and single point threaded the hole in the block to bring it back to spec.  As the block was square, with some difficulty in fixturing, this was done on a VTL and took around 6 hours per block to complete. 

Advent Tool specified their 20-TA-125-F6-9 1.850” Diameter 9” Overall Length 6 Flute Indexable Thread Mill.  Loaded with ATM-410A4FA Full Acme inserts (Stock Item) with 1.5” length of cut, this tool is now used in a Haas VMC where fixturing is a little easier.  Due to the inconsistent nature of the hardness of the hole, Advent takes 4 passes at 4 different Z axis depths (1” depth per pass) to generate the thread form.  Passes are started at the top of the hole and work their way down.  16 passes total with the Advent tool running at 370sfpm with .002” chipload per tooth.  All told, it takes 45 minutes to complete the part now as opposed to 6 hours!