Drilling 2mm holes through 19mm bolt heads in 316L

[SQT18MS]

In going to drill 2mm holse in bolt heads i various sizes, but the biggest ones are 19mm heads.

The drilling opperation takes place in a pretty stable drilling machine, with max 1000rpm and lowest feed are 0,08mm pr rev. The feed are too high so I have to feed by hand.

Got cooling of corse.

And oh yeah, the material of the bolts are 316L Stailess steel

Anyone have experiense with drilling small holes like these deep in stainless?

Witch drills did you use?

Anyone that can help me with this, I would very much appretiate it.

The job could pay well if I get more holes ot of the drills.

Now I get 2 holes out of every drill and its going SLOW

The drills I tried were the cheapese Prototyp drills, regular HSS with no coating. Got coated Osawa drills coming this weekend, will try those.


Any help here guys????

[laka]

RPM for a drill that size in stainless should be probably around 1900 RPM (at 40 SFM) and the feed probably around 0.001" to 0.002" per revolution. So run at max RPM, and feed by hand at what you think is a decent feed, make sure you get some actual chips and not just dust. Feeding too slow on 316 is not good. Coated drill should help, just make sure they're sharp. and you should be center-drilling first.

[davereagan]

Make sure there is real oil in your coolant, not all synthetic. A split point cobalt drill should hold up well with low cost. Stainless work hardens if you rub on it. Need to drill steadily and keep it cool.

[SQT18MS]

Thanks for the replys.

I am using a quaker coolant, not sure if its syntetic or mineral pr semi.

I get chips when I drill, not dust. The drill is cutting.

And I got 1000rpm max at the spindle, but have to feed by hand.

The drills Im waiting for are tin coated hss drills, I hope that will do the trick.

The first drill I tried were non coated hss drills.

Should have had this job in a machining center, but Im starting my own buisness whit minimal investments.

Any spesific drills in mind anyone?

[davereagan]

I just noticed you are in Norway, so any US supplier I could recommend would probably be out of reach. The point you use is important and it needs to be a split point, probably with a 135 degree point. Also, I am pretty sure uncoated cobalt will hold up better than TiN coated HSS. They cost about the same. If you go to www.mcmaster.com and look up these part numbers, you will see what I recommend: 3069A13 $1.48, 28765A12 $1.39 but short length, 29925A912 $2.89 with parabloic flutes I am curious how much you pay for drills over there. Just a friendly offer. If you found these prices attractive, I would be happy to order a bunch of them and then airmail them to you for no added charge at all. You'd probably have them in 6-10 days and total shipping cost would be under US$10.00

Dave

[SQT18MS]

Thanks for the offer davereagan, I would check out youre recomandations ASAP

The first drills I used were about 1$ a piece, and the coated ones I have orderd now are about 1.5$ so they are pretty cheap.

[SQT18MS]

So, now I have some Osawa drills and they last 20 holes (bolts) and I probably drill the hole 4 times faster than with the first ones.

Im very happy about this, cause it`s making me about 150$ in hour in a machine I paied 200$ for

Thanks for all the input guys, have a nice weekend

[SQT18MS]

By the way, the Osawa drills have coated tip and costs about 1,20$

Just orderd up 100 of them, and have 7-800,- bolts in the trunk that need drilling.

[davereagan]

Now I'm jealous. Are Osawa drills from Japan?

[SQT18MS]

Im not sure, found an italian page just now.

But would thing theire from japan.

Just google "osawa drills"

I got them from a local dealer.

Will post the spesific drill type, when I get to check it later this weekend.

[SQT18MS]

The spesific drill I used are called Osawa Item: 1386STI (I think) and Din: 338