Micro drilling help needed

[Chris_W]

My research and information from drill bit and autofeeding drill vendors are yielding conflicting information regarding necessary drill speed (RPM) and feed rate for my application. I need to determine the time required to drill through .090 inch thick my material (2205 Duplex) using a .028 inch DIA drill bit. Time needs to be ~3 seconds or less in order for my process to be feasible for production.

Can this be done with an automatic feeding drill assuming rigid mounting of both workpiece and drill?
Appreciate any response from someone well versed in drilling tiny holes in very hard metals(2205, 2507, Inconel 625).

Thanks

 

[btrueblood]

Been a lot of years since I was down that rabbit hole. Presumably, you have talked to Guhring? There is also a manufacturer of auto- micro-drilling machines out of Japan, who advocated very slow drilling speeds, so that rising torque could be sensed and counteracted by reversing the drill motion.

It really comes down to what you can stand - broken bits at some rate along with possible rework to remove broken bits from the workpiece, but fast cycle times, or slower speeds with lower (we never saw proof of this) breakage rates. This was in moderately cold worked (half hard?) 304 stainless.

 

[Chris_W]

I have purchased two types of bits(HSS-CO, carbide) from Guhring, and also bits from other manufacturers. The auto feeding drill manufacturers I've contacted have given wildly different estimates for drill speed. One said 4000 to 8000+ RPM, and another said about 800... At 800 RPM it would take ~ 13 seconds...

Unfortunately the equipment we have in-house is only capable of 2,000 RPM max and the run-out on this machine is too high anyway. I would like to find a way to test the feasibility without spending ~ $4K on an auto feeding drill.

Is the Japanese company you mentioned Sugino? I've had them quote a servo motor auto feeding drill. At $12K, this would be a though sell to management, especially since Sugino was unwilling to run a test for me using our material to prove the capability to meet our needs.

 

[btrueblood]

" Sugino was unwilling to run a test for me using our material to prove the capability to meet our needs."

That tells you something, I think. And yes, Sugino sounds right.

I'd find a local machine shop with a decent high speed lathe, and contract them to run some tests for you.

 

[Chris_W]

"I'd find a local machine shop with a decent high speed lathe, and contract them to run some tests for you."

Working on it now

Thanks

 

[btrueblood]

FWIW, when I'm doing hobby machining, this guy (Joe Pieczynski) is a great reference. This particular video is his approach to micro drilling.

https://www.youtube.com/watch?v=PqU5wS0J4MU