DRILLING E8740 STEEL 2

[punches]

HI
CAN ANYONE GIVE ME ANY INFO ON HOW TO DRILL THIS TRIPLE ALLOY STEEL.
HOLE SIZE .535 DIA. X .600 DEEP
MACHINING WILL BE DONE ON NEWER CNC LATHE.
THANKS TO EVERY ONE.

 

[scottmaha]

Hi Punches,

I have some experience with machining 8000 series alloy steel. I have found that Guhring makes a nice carbide drill for drilling this material. They have a coating called Firex that has a very high tolerance for heat. If you are able to introduce coolant through the tool on your CNC lathe, then I would go with Guhring's series #5510 and run at the following parameters:

340 SFM and a feed of .015 ipr, NO PECK

If you do not have the coolant through, then go with series #5514 and run the following parameters:

325 SFM and a feed of .012 ipr, NO PECK

You really should not have to go with the coolant through drill since you are barely drilling over 1 x diameter. However, it never hurts to run coolant through the drill. You may have a problem finding the exact size of .535". I not sure what your hole tolerance is but you may be able to drill at .511 and bore or ream the remainder out. Also, it is not necessary to spot drill for the drills. They are self-centering. Just make sure that the node left from facing the shaft is kept to a minimum.

Get with your local distributor about Guhring. Also, I think MSC handles Guhring.

Good Luck.