Drilling stainless

[Matts BitsNBobsParticipant @mattsbitsnbobs]

Hello all

As the title says, I have 24 10mm holes to drill in 150 0.9mm thick stainless, any tips? My plan is to clamp 50 at a time together and drill the 24 holes starting with 4mm then 6mm etc up to 10mm with plenty of coolant or cutting fluid? At low speeds, does this sound ok as I have never drilled stainless before?

Many thanks Matthew

[Matts BitsNBobsParticipant @mattsbitsnbobs]

[Involute CurveParticipant @involutecurve]

Hello Matt, I feel your pain… lol

I think you may struggle with this, I would prefer to punch the holes, what grade of stainless?

Shaun…..

[mechman48Participant @mechman48]

FWIW.. Stainless is a b****r to work with as it work hardens when you machine/drill it, just make sure you have spare drills to hand, get your surface speed correct for size / drilling & have plenty of cutting fluid. it looks like your planning on drilling through approx 45mm blocks if you stack plates together, that's some thickness to go at, I would have smaller stacks, & then you would have to really plough your drill through, better if you can use carbide drills, I'm sure other forum members will have better advice on how to drill Stainless, I only use it on little items if need be otherwise I would prefer to use silver steel.

George

[frank brownParticipant @frankbrown22225]

As said SS work hardens so the way is to keep the feed rate up, I think that you will run out of muscle with a stack that high. I would use a 1/2" stack and hang on the drills handle, selected so you can go through without changing handles. I use Rocol RTD cutting oil for this sort of job.

Frank

[Anonymous]

I cant see you drilling through a stack of 50, the key to stainless is to keep steady constant pressure all the way through. The slightest let up forms a hard layer in the stainless even on the easily drilled 304, 316, 430 etc. However you  clamp them up there will always be a miniscule gap between each one which will cause a bit of rubbing/hardening and it will become harder the deeper you go quickly dulling the drill. Drilling pilot holes is also a bad idea for the same reason. I've drilled 10mm holes in 316 and 430 sheet using HSS in one with no problem. May take a a lot longer but I'd be doing them one at a time, if you've got some scrap pieces try it and see.

Edited By Mick Berrisford on 06/11/2014 23:51:50

[HopperParticipant @hopper]

Practice drilling on some scrap SS first and find out what works and what does not for you and your machine.

[Eric CoxParticipant @ericcox50497]

Would you alter the angle on the point of the drill especially if you drill them one at a time ?

[Neil LickfoldParticipant @neillickfold44316]

If it was me, I would use a 10mm centre point sharpened drill, at 150- 200 rpm max, and 0.1 to 0.18mm per rev with flood coolant. In the past I have had best results when doing thin shims like you are doing is to have a 1/8 or so plate as a top plate and base plate.This stops the top shim layer from lifting up. Keeping the stack short reduces total heat build up.

Basic rule of thumb is 1/2 the speed and twice the feed.

Neil

[Trevor WrightParticipant @trevorwright62541]

Would also recommend sandwiching the plates as a 10mm drill will roll burrs if not razer sharp. It will not be sharp for long either if you run the drill speed too fast. If they burr you will spend even more time removing them….

Packing them 50 deep will work but you will need to keep the drill point cool, downside is the pilot drills will almost certainly wander as it will keep hitting 51 skins of plate, the bottom plate could be a long way out of position as the larger drills will follow the original hole.

If drilling on a mill I would recommend drilling 3/8" (9.5mm) and sizing with a 10mm end mill, if sharp, it will leave a size hole and the edges will be razer sharp and burr free, it will also align any errors caused from drill wander.

Trevor

[Matts BitsNBobsParticipant @mattsbitsnbobs]

Thanks for the replies guys, I will let you know how I get on

[doubletopParticipant @doubletop]

These are 5mm stainless, the angle is 3mm. Over 150 holes, mostly 6ba clearance with some at 10mm. The larger drill sizes have been sharpened the 4 facet method. They didn't struggle at all. I used a single 6ba clearance drill for the whole job, nothing special but new, from RGD I believe

 

 

The trick was using Rocol RTD. All done in one afternoon

Pete

Edited By Doubletop on 07/12/2014 09:37:04

[Author]

Posts