Drilling into Hardened Steel, what drill bit required? 2

[kiwitom235]

Hello guys,

we have plate steel S235 JR (1.0038), with surface treatment TENIFER Q.

Can we use a HSS cobalt drillbit for this or require something harder?

 

[BrianE22]

From what I can find, that process (Tenifer Q) produces up to 75 Rc hardness for the coating. I don't think you'll be able to drill through that. Even a carbide bit would have trouble with that.

 

[dik]

I used to have a rotary grinder bit that would drill through industrial hacksaw blades... it would grind its way through. I think that is what a machinist would use.

Dik

 

[dgallup]

There's always ram EDM & lasers.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[metengr]

Industrial diamond drill bit.

 

[EdStainless]

And lots of coolant

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[kiwitom235]

But it's only a thin surface layer right(few microns)? So once through the first layer it would just be pushing through hardened steel?

 

[GregLocock]

You've had 4+1 sensible suggestions. Let's see the video of your approach.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[arunmrao]

Have you checked for a solution from the manufacturer? They surely must have a recommendation. I am familiar with Hardox grades and they recommend appropriate drilling solutions.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[tbuelna]

The diffusion layer of this liquid salt bath nitro-carburize case hardening process is probably around .004"-.008". The outer compound layer is much thinner but extremely hard. The core material ends up at moderate hardness due to the relatively high temperatures (~1075 degF) used with the liquid salt bath nitro-carburize process. Probably best to carefully grind thru the local thin case hardened surface, and then use a CBN coated end mill to machine a shallow counterbore to the final hole diameter, which will provide a stable surface for drilling thru the softer core material.

 

[btrueblood]

I wonder if friction drills (e.g. flow drills) would work? I wonder enough to have sent them an email asking about hardness limits for their products.

 

[btrueblood]

answered my question here:

http://www.formdrill.com/english/faq.htm

- they claim any steel up to 160 ksi (presumably ultimate strength?)

Flow drill just responded, the say they can drill most steels, but not generally tool steels or heat treated steels. They work on dual phase steels DP800 and DP600.

There you go.

 

[arunmrao]

Thanks btrueblood, you just solved my recent problem.


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[btrueblood]

Cool Arun! I've been meaning to get one myself just to play with in the shop.