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Lower Thrust

Thrust limitations are a concern on some machine tools with larger sizes of twist drills and spade drills. Rotabroach Cutters have much lower thrust requirements, and are seldom a factor when selecting equipment. An approximate thrust force value can be determined from the following equation:

T=.7 x WT x FPT x NT K_c

        Where:

- T = Approx. Thrust (lbs.)
- WT = wall thickness (.188, .218, .264)
- FPT = Feed per Tooth (.002 - .005 ipt)
- NT = Number of teeth (Divide by 2 for "Hougen-Edge" geometry)
- K_c = Machinability factor as related to tensile strength

 

Type of Material	Kc
Free machining and low carbon steel	239,200
Plain carbon steel BHN 125-160	254,000 283,000
Soft alloy steel BHN 170-210	297,000 312,300
Med. hard alloy steel BHN 220-250	326,000 341,000
Tool steels hot & cold worked BHN 210-250	355,000
Hard alloy steel BHN 260-300	370,000
Stainless	370,000
Cast iron BHN 180 max.	167,000
Cast iron BHN 180-250	196,000
Cast iron BHN 250-300	255,000
Aluminum	106,000