Shown here is a TiN-coated drill bit. Titanium Nitride can often be easily identified by its golden color.
TiN is a hard ceramic coating that is often used on steel drill bits and other machine tooling, and it provides several benefits, mainly longer edge retention and reduced friction.
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In other words, TiN-coated drill bits should last longer than uncoated bits, and you can often push them faster too.
It does have its downsides. For example, you can’t use TiN-coated drill bits on aluminum. Well, you can, but you run the risk of having the aluminum smeared all over the drill bit, leading to worse performance or other complications. There are ways around this, but many manufacturers don’t recommend the use of TiN drill bits on aluminum.
I use TiN-coated bits on wood, because it’s convenient. When I drill steel, I use HSS, TiN, or cobalt drill bits. Or black oxide if it’s light duty work and that’s all I have around.
Different drill bit coatings and materials have different benefits and tradeoffs.
The other day, I posted about a Makita wood, metal, and masonry drill bit set, and saw some strong dislike for TiN-coated drill bits. This brought me to wonder:
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What do you guys think about TiN-coated drill bits?
There are other gold-colored drill bit coatings, such as gold oxide, and gold ferrous, which is what certain Dewalt PilotPoint bits are coated with. It’s been hard for me to find any solid details about these types of drill coatings. According to a few machining forum posts, they’re a step below TiN.
Speaking of which, although I have industrial bits at my disposal, I still love my Dewalt’s 29pc PilotPoint drill bit set ($53 via Amazon and eligible for their holiday discount) for drilling into wood and plastic, and I use them on occasion for light metal drilling as well. Then again, I’ll use them for things like 1/8″ aluminum plate, and not 1″ aluminum bars and things like that.
Drew M
I’m reminded of some carbide inserts we got for one of the metal lathes. They were TiN coated but the coating was just thick enough to give them that gold color. So, after about 5-10 min of use, the coating had worn off the insert and you would have to back the machine off to bare carbide settings to prevent it from breaking the insert.
So, the answer is that there is more to it than just putting TiN on the tools and using them on the correct materials. The coating has to be of an appropriate thickness for it to work.
These days, it seems they put TiN on everything because…. shiney sells?
Bruce
In wood, who cares? It’s soft, it works. In metal there is only one coating worth using, oil.
fred
Oil or cutting fluid – yes . Perhaps with the exception of cast iron – where dry cutting is the norm. An old candle is also not a bad lubricant for Forstner bits and Brad Point bits in wood – as long as the wax doesn’t get all over the place and mess up your application of glue or finish.
fred
For general drilling tasks at home – I’m more a fan of my black oxide coated twist drill bits – probably because they can tackle drilling into aluminum, brass, mild steel and wood. My Lee Valley set of brad point bits are bright finish – as are my WL Fuller Plexi-Point bits for plastic drilling.
I mentioned in the post about the Makita set – that when I worked we had some coated tooling for cast iron applications. I think it had more of a dull-grey look than the yellow-gold of TiN – and our machinist thought it performed better. But as I said – I neither recall what it was – and did not have any statistical proof that it really performed better. I guess, however, that for cutting cast iron – where our machinist eschewed the use of cutting fluid the extra lubricity of the coating helped out.
Drew M
Most of my metal working experience is in stainless steel and exotic nickel alloys like Inconel 625 and 718. I have a ton of experience with coated taps in stainless and TiCN coated taps are the only ones I’ll use for that. That said, I mainly used AlTiN coated carbide tooling but just before I left that job I was pretty excited to try a new coating that MA Ford was using on their tools.
If all you do is aluminum, ZrN is an amazing tool coating. It sort of looks like TiN but a slightly lighter color. I honestly wonder how well ZrN would work on other materials but machine tools being what they are, most tools coated with ZrN have geometries optimized for aluminum and nothing else.
fred
We had one shop where we did pipe fabrication and some metalworking. Mostly mild steel, ductile iron and some cast iron. From time to time we had jobs with SS. We did a job with some Hastelloy and Carpenter 20 – where another contractor was working welding aluminum pipe to carry some sort of pyrophoric stuff.
ken
I use HSS for everything now and I couldn’t be happier. I’ve had my share of every type of bit and coating but a good quality, US made, jobber HSS set has filled my (largely automotive) needs.
Hang Fire
In my experience, the quality of the cutting tool’s steel is the predominant factor. I think TiN has gotten a bad rap because it has become a universal marketing tool (after all, it’s an acronym that guys can memorize and sound smart, and it makes drill bits pretty), where no one really understands what it’s for (and not for).
Construction workers and homeowners actually drill a fair amount of aluminum- metal studs that replace 2×4’s, vinyl/aluminum railing, flashing, light fixtures, etc. Chances are high that the bits they grabbed at the home store are TiN plated, they get galling, and feel cheated.
Doresoom
I’m pretty sure most metal studs are made from galvanized steel, aren’t they? Either way, the rest of the materials you list do prove a good point that TiN may not be the best general purpose bit out there.
Hang Fire
There are plenty of both, Lowe’s carries aluminum studs.
JeffD
I don’t trust anything ‘coated’.
I put together a set of molybdenum bits that handle anything i throw at them.
Nathan
Nice mention of the ZrN coatings – I sort of thought that was useful in AL due to the silicon content in most AL alloys.
I agree about the quality of the bit – before the coatings is far more important than the coating. some are made of trash metal, IMO and then coated. They are going to go bad quick and just to coated dull bits that gum.
Now I have 2 quality sets and one is just HSS and the other is cobalt steel. So I don’t own any.
AngryDrumGuy
Stuart-
I’ve been watching the price on the below linked set flux for over a year now.
Any argument against the set I’m watching over the DeWalt set you recommended?
Looking for a good set to travel and not worry about missing sizes.
http://www.amazon.com/DEWALT-DW1269-29-Piece-Cobalt-Pilot-Point/dp/B000R94EFG/
Brian
I splurged on that set about a year ago. I figured if I’m going to get a nice set, get a NICE set. (Im sure some would say these are still scrub bits… but compared to the chinese crap Ive had before, they are nice I think)
Anyway, I expect it can drill pretty much anything. the case is very nice, well designed, sturdy, convenient. The bits are very sharp, work great, I have only had the opportunity to drill wood and aluminum, but they worked great for that. They are aggressive, so they really want to pull through the backside on the exit, so be careful, use a drill press or a sacrificial backer.
fred
Unless you are regularly drilling hard metals – I would recommend a HSS set with Black Oxide finish – Here’s one – I think USA-Made – and may be eligible for MSC’s 25% off sale:
http://www.mscdirect.com/browse/tnpla/02500106
Stuart
The one I linked to is going to be better for all-around use, the Cobalt drills you linked to are more meant for drilling stainless steel and other hard steel materials.
Cobalt drill bits are more brittle, and so while they can be used for general purpose applications, they’re not the best choice.
AngryDrumGuy
That’s good to know and will save me a few dollars. Thanks!
EMILIO E GONZALEZ
I wouldn’t waste my money on big box store , gold painted drills. I have a large collection of drills of high quality, with all type of coatings and bright.
For wood, Freud makes great bits. For metal, I use Guhring, OSG, Melin, etc…
I wouldn’t bother with those fake TiN bits.
Noah
I got over the fetish of fancy coated drill bits from the box stores. Now I just keep black oxide coated American made bits in my kit and am developing my sharpening technique.
Graham
BINGO! At last. Someone said it. I’ve read dozens of posts & decided that ignorance is our greatest downfall. In UK we sadly no longer train the number of apprentices as we once did. So unfortunately people are prone to believe what they are told by the man who is trying to sell them something. There is no substitute for knowledge & it is all there if you just look & read. Learn how to grind your drill bits. Learn about speeds & feeds. Learn about the material you intend to drill. Learn about the common myths. “it wouldn’t cut butter” not many tools will. They will smudge it. Generally, the softer the material ie wood. The sharper the tool needs to be. Really soft material may cut better if you freeze it. Another myth is “stainless steel is hard” it isn’t, it’s tough. Titanium is also tough. A low speed & high feed works well. The list of odd sounding stuff goes on & on but it is all there to read about if you can be bothered. Trial & error can bring surprising results in research & development but can work out devilish experience if your trying to drill a broken stud. Read, Read, Read….. THEN DRILL
John
it seems to me that the vast majority of the diy and home owners are using these drill bits in hand drills and not drill presses. When drilling in metal, you’ll see these users put it on speed 11 on their drill and grip and rip into the steel. Slower is better of course but most hand drills don’t go slow enough. I used to never be a fan of step bits, bit after using thr Milwaukee ones, it appears they adjusted the angles on it for specifically high speed application. So in a hand drill it’s amazing. I have to see if that’s the case with their new Red Helix Cobalt etc bits. These home sale drill manufactures should be designing the bits for those customers, i.e. high speed hand drill application.
fred
Of course we know that feed rate as well as rotational speed can be optimized for the type of material being cut and its hardness. Ideally the drill point angle and geometry, plus flute style might also be selected based on these characteristics – and then all this might be tweaked based on the hole diameter and depth of cut. So in a tool room there might be a lot of choice sorted in dispenser cabinets – and some charts to inform your selection. And naturally what you buy – will be based on what work you do. We had 2 distinctly different businesses – and the long parabolic flute fishtail point bits or the 60 degree point drills for plastics that we had in the cabinet shop – would never do for drilling cast iron in the pipe fabrication shop. The homeowner with one set of bits to tackle most everything will probably wonder when the go-to twist drill bit wanders and skips on the surface, will not cut hard stainless steel, work-hardens some mild steel, crazes hard plastic, may not bore a truly round hole and galls aluminum – to name a few issues that might be encountered.
Graham
You are right about the use of pistol drills & again it seems very common to try to drill steels with the highest speed & take it steady. You are only going to blunt your bit & toughen or even harden the work piece. The experienced metal worker will use the slowest speed, have a washing up liquid bottle full of anything rather than nothing at hand & then get his full weight behind the drill. It sounds like madness. In a construction environment bad tool practice seem to just keep on being past down like gospel. If I were seen using a massive SDS drill with the hammer turned off. A Chuck adaptor fitted & a 6mm drill in the chuck, I would be laughed at. It’s not the power of the drill I would want but the lower speed.
Jerry
The very best bits I have used for all around drilling, pretty much everything except cast iron, are the black oxide ones. The quality of the bit, and the sharpening angles matter more than coatings, in my opinion.
Grady
1 Cobalt, any steel
2 HSS, most steel, aluminum, wood
3 Tin, most steel
4 Black Oxide, most steel, aluminum, wood (light duty)
Regardless you must use proper lubrication for the material you are machining. Also you must clear your chips . Chip build up is the most common cause of heat, dulling, and galling.
mosh
TTM and IVY classic make great bits
KL
As mentioned several times above, black oxide HSS (quality US made!!) is the most bang for the buck. Do not buy bits from Dewalt, Milwaukee, Home Depot etc. Your best bet by far is a machinist supply like Enco or MSC.
Your next task is learn to sharpen. Empower yourself. It’s not that hard. When you sharpen the TiN goes away anyhow. TiN is mostly a marketing gimmick – particularly in homeowner or hand drill bits. The only way you’d see measurable benefit is in a machining center (due to consistent, proper feeds and speeds) and flood coolant.
Mau
I usually use HSS bits for Aluminium (mostly 2024 and 7075), and Cobalt for Titanium, although the Cobalt bits are more fragile and expensive than the HSS. I don’t use drill press, only by hand and normally I prefer reamers. IMO TiN coating is a marketing gimmick, used just to make poor materials shine.
fred
Mau – you said:
“I don’t use drill press, only by hand and normally I prefer reamers”
We would ream sometimes too – even if the holes were drilled on a stationary drill press or cut with an annular cutter using a magnetic drill press. Reaming with a bridge reamer was of particular usefulness when drilling through 2 plates , making connections on wide flanges etc. where you needed to make sure the holes were concentric/aligned properly. Bolting up a set of even slightly misaligned holes might otherwise create unwanted stresses in the steel.
Mau
Yes, I totally agree with you, but if you can’t put the piece under the press (normally it’s too big) going by hand is the only option. You can of course use guides, and normally you use them, but usually the tolerances for the holes given by the project are big enough to tolerate a bit of misalignment, especially considering that the package is usually few millimetres thick.
dll932
Some good info here-thanks, guys!
I read that a good lube for cutting aluminum is chalk, BTW.