Need Help!- drilling ss304 and ss316

[shay z]

Hi all,

I need to drill ss304 and ss316 hole diameters are from 5/2 and up to 14 mm and I have to make thousands of holes.

the machine is vertical cnc mill with no through the tool cooling.

I did that job on manual drills and this is my first time drilling it on cnc so I need recomendations for drills (brands and drilling data).

thanks in advance.

[PinMan]

I drill TONS of SS, everything from 303 to 17-4PH. The best drills that we have come by in our experimentations are Nachi Powdered Metal Drills. They are only slightly more expensive than Cobalt Drill and last 8x to 10x longer.

And with the AG and SG coatings that are specifically for Stainless, you are going to be hard pressed to find a better deal.

Nachi Drills

[stevo1]

All I use to do was 304 and 316 stainless. A lot of drilling on it. Where we ran into a lot of problems was if it was not the EZdrill 316. We ended up burning up a lot of drills and mills when it wasn't (mostly mills).

We used some Cobalt drills so Pinman is probably right with the drill recommendation. Are main drills we used soildcarbide. They are more expensive but we ran multiple machines at the same time so starting it up and letting it go on its own for hours on end out weighed the cost. It was also slower then using the cobalt. On the carbide drills we ran 30sf and .005-.009 chip load. Also make sure you peck drill it.

Stevo

[Geof]

Originally Posted by stevo1 .... Also make sure you peck drill it. Stevo

We do not drill much stainless but the times I have done it I tried to avoid pecking and I have seen here on CNCzone people recommend to avoid pecking because every time the drill re-enters it has to break through a surface work hardened from the previous peck.

So is it really better to peck? Being a cheapskate I don't like burning the ends off drills but I do like to gets things done quickly and cheaply.

[stevo1]

There are many ways to skin a cat. I don't peck when running a indexable drill or a harder material. 316 likes to not chip so had to back it out to break the chip. It will probably be some trial and error. If your drilling and there is a long burr coming out of the hole that never breaks, thats not a good thing. 316 likes to work harden very easily. I am sure there is a better way of doing it but we ran hundreds of thousands of holes for over 15yrs in that material and never had a problem. However it was probably not the fastest process. But running more then 1 process at a time paid for it.

Stevo

[PinMan]

We avoid carbide simply for the fact that a lot of our parts are gundrilled tubes, so with the void of material there carbide chips too much. On our solid parts we do use some carbide and we go with Garr Tools.
The good thing about Nachi drills is with the tip geometetry and the recommended speeds and feeds that they provide you shouldnt ever have to peck. The chips come out really nice and small. You can peck if you are drilling pretty deep, but then I would recommend fast peck to shorten the cycle times.

A common example for me:
6.9mm AG-SUS Drill LIST6596P ($15.37 through our distributor)
Drilling ss316 @ 50SFM
702 RPM
0.009 IPR or 6.3261 IPM

We get on average 8000 holes @ 0.650" deep before the drill wears. Whereas, HSS is going to last you about 1000 holes, and cost you $5.09 each.

[Khalid]

Originally Posted by PinMan A common example for me: 6.9mm AG-SUS Drill LIST6596P ($15.37 through our distributor) Drilling ss316 @ 50SFM 702 RPM 0.009 IPR or 6.3261 IPM We get on average 8000 holes @ 0.650" deep before the drill wears. Whereas, HSS is going to last you about 1000 holes, and cost you $5.09 each.

Impossible 8000 holes @0.650 deep before the drill wear... I have used HSS, HSco and Carbide drills and i never succeeded getting more than 35 holes using Peck drill without breaking.. The thickness is 30mm Stainless steel...

8000 holes with one drill without resharpening seems absolutely impossible task....