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 Kc
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)
- Kc = 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 |
| Soft alloy steel BHN 170-210 |
297,000 |
| Med. hard alloy steel BHN 220-250 |
326,000 |
| 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
|