321 DESTROYING DRILLS

[ksborsenberger]

Ive had a problem on this last batch of 321 SS parts that ive ran. For some reason even though i am using the recomended SFM for 321 which is 55-90, as well as a feed rate of .006 to .008 for a drill between 3/8 and 1/2, drills keep getting destroyed. They will run 20 or so parts then the tips will be gone. Material that it is going into is clean, using carbide drills, as well as high speed steel, the results were still the same. I adjusted the speeds and feeds during run, however nothing ever got me to that sweet spot. I was wandering if anyone else has ever had this issue. This was on a cnc 2 axis lathe. Ø.421 for the drill.

[gcode]

are you spot drilling before drilling

if so, make sure the tip angle of the spot drill is equal to or bigger than the tip angle of the drill

[The Cathedral]

We just ran a boatload of 321 parts. Using a .433 Iscar Sumo drill (carbide tip), no spot, high pressure coolant at 180 SFM and .004 fpr.

 

For carbide I would say your speed is way too low. No spot if you can get away with it or do like Gcode pointed out and check your drill angles. Coolant thru is a huge bonus.

[jeff]

I agree, you're going too slow. What brand of carbide drill are you using?

Here is a link to Guhring's speed and feeds for their drills for stainless:

http://www.guhring.com/Documents/tech/speedfeed/8510.pdf