Any suggestions on tip geometry? We design and make all of our own cutting tools. Right now it is just a 118° point, straight flute, step drill.
Also you said way too slow. Would you agree with Sami and suggest a .003"/rev feed? What RPM would you recommend?
Ok, that presents problem.
A) I would not put the same rake and clear angles on carbide as HSS. Does your design account for this.
B) edge prep? any, none?
C) type of Tin coat, PVD, CVD, thickness?
I'd be up above 400 SFM on the minor diameter and way past your feed per rev. but tool geometry of the flute and clearance behind the cutting lips matter.
I could give a shit about point angle but it does interact with the clearances on standard grinds or the front rake and belly/hook if your flute is fixed.
Not even sure if you are in a C-2 or C-5 carbide,
For sure I'd try faster and harder. Pull the tool
very early and look at the wear under a microscope. What is happening?
Which is pissed off the flank or the top? Weld? Coating gave up the ghost? Tip (flank) shows signs of rubbing? Micro-chips which a buff hone may fix?
I don't think you will see thermal cracks as you are not in this range for speed.
As a random wild guess I'd think small chip welding that pulls out pieces of the carbide as it is forced to cut. Good news is that this only happens in a fairly small range of speeds.
Going faster gets you out of this badland. Going slower also does but slow is rarley a good option.
The real trick here is to pull tools way, way before they go bad and look at them.
On a 6000 pc tool I like to see it at 10, 500, 1000, 3000.
Nobody wants to pull a tool still working but it's the only time you see anything that lights up that little bulb.
Chip the crap out of end, give me 1/2 of a broken insert. I can't tell you anything at this point and can simply pass out wild guesses of things to change.
There is a whole nother way out of this problem and for sure this is common.
Try lots of feeds and speeds, try lots of coatings and carbides. You will hit a "works for you" combo at some point.
Sometimes the shotgun approach is faster to the finish line.
Bob