2 inch insert drill recommended speed and feed p20 tool steel.

[TommyGunzz]

I gotta job in our Mazak quick turn 250 lathe today and I found a 2inch kennemetal insert drill in the cabinet that I have never used before. It's one of their DFT drills with trigon inserts and thru coolant. I'm more of a mill guy myself but really been enjoying the mazak lathes we have. The material is p20 tool steel less than 35 Rockwell. The only inserts we have for that drill are a kc7935 grade. Based on the kennemetal book I found online it looks like I should be using a kcpk10 for outside insert and kc7140 for inside insert for stable cutting conditions. Sfm says 935 and feed of .007 to .012 ipr. That sounds like a lot to me but again I don't have those grades on hand. I'm going 5.2" deep with the drill. What do you guys think would be a good starting point? Only got 1 part to do. I was thinking 250 to 300sfm at .006 or .007 ipr.

 

[Milland]

May not want to lowball the numbers as you might not get the best chip breaking. I think I'd call a Kennametal applications engineer and tell them the inserts and material you're drilling, and see what they suggest given your machine's available torque.

 

[TommyGunzz]

May not want to lowball the numbers as you might not get the best chip breaking. I think I'd call a Kennametal applications engineer and tell them the inserts and material you're drilling, and see what they suggest given your machine's available torque.

Yeah I think I'm gonna do just that tomorrow morning. Yeah I don't Wana just guess at it either.

 

[Philabuster]

I gotta job in our Mazak quick turn 250 lathe today and I found a 2inch kennemetal insert drill in the cabinet that I have never used before. Only got 1 part to do. I was thinking 250 to 300sfm at .006 or .007 ipr.

250 SFM is reasonable, but drop the feed rate to something like .004". When you run the part, run the feedrate override at 50% as the drill engages the part and WATCH the Z-axis load meter. Increase the feedrate override until the load meter is 80-100%.

This will allow you to go from .002" IPR to a max of .008" IPR, which I do not think your machine has the thrust to push a 2" drill in heat treated material at .008" feed.

 

[LockNut]

P20 is a relatively free machining tool steel. I love machining P20. 250 SFPM sounds reasonable to start for drilling. Feed could start at .006" per rev. and adjust to 80% spindle load. I do agree though that driving a 2" drill will be problematic no matter what. But it's worth a try.

 

[camhead420]

I found the problem with a big insertable drill like a 2" is not having enough coolant pressure.
The 1.5" size coolant holes are smaller and provide pressure. the 2" holes are larger and it was just not enough to push chips out. These are Seco drills. btw