Deep hole drilling 1

[woodyrod]

Hello all,

I will soon need to do some deep hole drilling for a job we have on. It involves a hole drilled into 35ncd16 steel (annealed condition), to about 180mm deep, likely a blind hole, but yet to be seen how the job will be chucked up.

We have a Mazak SQT15MS, and the job will be done on this machine one way or other.

Looking to drill a hole from one end, rechuck in auto to second spindle, finish other end of hole as it is a different size and not so important for being central.

Am thinking of using a gundrill, STS or Double tube drill for this???

The hole will be reamed when finish. Finish size is 22.20mm making the hole ratio about 8-9 to 1.

 

[unclesyd]

I would contact Allied to see if they have a spade drill that can meet your requirements. A spade drill will vastly simplify your coolant requirements and set up. Depending on you quantity you can get indexable tooling.

If your quantity and finishing requirements are high I would also look at the Engis one pass system of diamond honing.

http://www.alliedmachine.com/home.cfm

http://www.engis.com/products/honing/tools.php

 

[droogeh]

I use titex drills for deep hole drilling. I drill 4mm dia holes to a depth of 120mm-150mm without fuss in duplex and other 'difficult' metals. Now superceded by EDM drilling. (although the size you want is a little bit big for EDM.) Gun drills are a good option at that size TBH. Although i got sick of grinding them.

 

[EVERFABCHAD]

I agree, Go with Allied very free cutting, holds size, cheep inserts, many sizes available etc....etc....

 

[TVP]

For that size of hole I suspect that gun drilling or a tube drill will be the most productive. We routinely gun drill 13 mm holes into 1035 shafts using Guhring tools, and I can't imagine a conventional drill meeting the necessary requirements. I would definitely contact Mazak to discuss what options they recommend regarding toolholding, as this may drive the process more than the actual cutting rate/cycle time.

 

[hbma]

Useful link to Allied, thanks!

Specialist 3 & 5 Axis Machining

http://www.midlandalloy.com

 

[Astonlee]

I think you should also consider the Advanced Carbide Tools Nine9 10xD Super Power Drills for this application

 

[ornerynorsk]

It's hard to beat a gundrill. Worth checking out, anyway.

 

[woodyrod]

Hello everyone,

Have been keeping an eye on this thread, although not posting. An update of sorts for drilling:

We have now tried a few options, only one so far working: that being a std HSSCo drill. Guhring and other insert drills did not work at all, but I havent tried the allied unit.

We have had so much "expert" advice from tooling suppliers, with NOT ONE of them being correct. This is why we now use the std drill. Going one step further a gun drill may work, and probably make a much nicer hole.

The one issue we have is coolant pressure, which is as low as 10 bar, so all options need to take this into account.

 

[TVP]

woodyrod,

Maybe I should have been a little more specific when I mentioned gun drilling with Guhring tools. We use a single flute gun drill like the Guhring EB 80, not an insert-type drill. Page 24 of this .pdf shows the large diameter, long length gun drills of the single flute variety:

http://www.guhring.com/documents/catalogs/drills/Gun-drills-e.pdf

 

[racookpe1978]

I've recently used the hollow core drills for several 6-10 inch deep, 5/8 through 1-1/4 dia holes in turbine flanges.

They worked well, with no problems.

 

[racookpe1978]

I found an advertisement from "cobracut" "structural steel drills" in a recent delivery from American Punch Company.

Haven't used them, but they have two internal holes running down to the bit cutting faces for lubrication. Sizes are from 7/26 inch through 2"; lengths from 9" up to 17"

 

[Viktor]

If you have available 10 bar coolant pressure, just forget about gun drills at all.

Viktor

http://viktorastakhov.tripod.com

 

[jhartsock3]

If you do go with the allied wich we use to use on mazak all the time. You might have a coolant issue not quite sure of your machine if you have through coolant as for diamter and depth. We always started with a center drill and rammed the drill in they are good drills but pron t vibration and chatter. Also make sure to indicate not only the tip but along the length to make sure you are straight a little off with create some issue. And I would deffinetly stay away from a peck cycle.

 

[JonGould]

We just finished some parts in 38Rc 4340 with the Kennametal KSEM drill which now comes in lengths up to 10XD. We were not getting consistent results reaming so after initial tests we found that we could hold 35Ra finish and had no more than .0018 walk in 9".

Like others have said, this costs far less in tooling and cycle time than gun drilling of any sort, and a mishap won't cost you a $1,200 drilling system.

Surprising was that roundness was .0002; we expected better than that though we did not need it for this application.

We have also been looking into the Allied Gen3Sys drills; however, we don't have any performance data on them yet.

http://www.kennametal.com/e-catalog...ction=push&item=category:6973&logo=kennametal

 

[woodyrod]

Yes, even after this long, we are only just getting into drilling a decent hole. We have now acquired a Mapal drilling system, which is awesome.

The Mapal is not like the Allied unit, as it is a complete head, rather than a spade type flat bit. ALso has 4 x guide pads on the sides of the head to limit sideways movement.

We are using 0,3mm (0.013")/ rev and 800 rpm rotational speed. Penetration is excellent, and of course there is no pilot.

Now we are onto getting a new reamer to go with this drill.

 

[unclesyd]

Here are two systems that we have use for precision hole in tool steels. The diamond hone from Engis is the best. One feature is you can't go oversize. The Helical is essentially the same thing.

http://www.engis.com/products/honing/

http://www.helicallap.com/