HSS vs Titanium vs. Cobalt drills.

[John_N]

Does it make much of a difference for drilling mild steel or brass?

John

[Al_Messer]

Well, I cannot answer that, but I will confess to using High Carbon Steel drill bits with success in mild Steel.

[Rwilliams]

The titanium nirtride (gold colored) coating on drills fills in the microscopic pores in the HSS making the chips clear better. It also provides a very thin but harder surface. This allows the drill to stay sharper longer and run at faster speeds with the same material being drilled. With less cutting resistance, they seem to run a bit cooler and do not expand as they are used to drill deep holes. The holes also seem to be much smoother inside. I have some very high quality titanium nitride coated drills that will make a hole appear as if a reamer was used. What many seem to like is the lack of a built up edge on the cutting lips. Things just can not stick to it.

In this metal working business, you generally get what you pay for. In a production situation, titanium is the way to go. It adds very little to the cost of most drills for the return on your investment. Any more, I always look for the titanium coated tooling.

[jutz]

I used to buy TiN coated cutting tools but then tried to tap a piece of stainless (304 to be specific) with a TiN coated tap and found it required significantly more force than an uncoated HSS tap. TiN coating works great on carbon steels and cast iron, has little impact on aluminum (most manufacturers don't recommend it for Al, though) and is detrimental on a number of alloy steels so I no longer buy TiN coated cutting tools.

As far as the HSS vs Ti vs cobalt question, there's really not much difference on mild steel or brass. Personally, I get cobalt when possible because it seems to have less tendency to rust on those occasions when I forget to put one away. I only have one Ti drill and the only advantage I see is it's significantly lighter than HSS, but that really only matters for tools you have to carry around.

[alanstepney]

In a production envirnoment, one needs the highest speed and maximum time between sharpening, and there, the drill material is important.

In the home workshop, a slower speed / feed is of little importance, whereas initial cost often is, and for most people, resharpening drills is a chore.

My drills, I suspect like most peoples, are a wide range of types gathered over many years. The sole criteria being "is it the right size?"

[Doug_C]

I have never seen a solid titanium drill bit. I'd imagine they would be lite, but not good for drilling much but soft materials?

Both carbide and TiN coated HSS will be very brittle. Coated drills cannot be readily sharpened with removing the thin layer, but if it does need sharpened, it must have already chipped. Carbide drills are no peach to grind either, unless you have a diamond wheel.

I have looked over some of the import TiN coated carbon bits. It is so thin, it may as well not be there, but for a sales gimmic. Carbon drills are much harder than HSS and will also chip easier when drilling under high pressure or impact. Coated HSS is again a short lived bonus.

As had been mentioned. When time is money, a cutter not making efficient chips with an extended life as possible. It becomes a foolish flush. The cost of the bit is minor compared to no product flowing.

At least with HSS and Cobalt, they are resharpenable in the home shop. The cobalt will hold an edge longer under production demands or hard cutting materials. But the home shop rarely cuts exotic metals.

Industrial quality HSS is good enough for 99% of home shop projects. It is good to have on hand a few Carbide bits for hardstuff. I think it is best to buy the fancy bits, only what you need when you need it, if buying it new. Keep to HSS for the every day stuff.

DC

[jutz]

I've used solid Ti on cast iron and mild steel. The surface is nitrided so it actually wouldn't work all that well on most other materials and it can't be resharpened. I bought it just to see how well it would work, didn't even open the package for over a year.

[Rozati]

I apologize for bumping this old thread. I'm just posting my experience as a very junior home hobbyist who is starting metal work

I bought a variable speed (750rpm is the slowest setting which I know is a bit too fast for metal drilling but anyway..) drill press and have been using titanium coated drill bits like this https://mechanicguides.com/best-drill-bit-for-metal/ to drill into 3/16" or 1/4" steel. I always found I have to use a lot of WD40 to keep the bit cool and that I can drill around 10 holes in 3/16" steel before I notice the bit is dull. I know this because it heats up much quicker and takes longer to drill through.

I've been reading through the many, many threads and posts on Cobalt vs Titanium coated and figured I'd invest in a cobalt bit set from Canadian Tire (link).

After using the cobalt bits for a couple of weeks now, I can say that I find them to be much better performing when used for drilling through mild steel. I've drilled maybe 30-35 holes in total using the 3/8" bit and it feels as sharp as day 1. I don't have to use much WD40 to keep the bit cool. I can drill maybe 3 holes and the bit is still comfortable enough to hold, couldn't do that with the titanium bit and it cuts cleaner and quicker.

When I was using the titanium coated bits, I would get little bits of metal flying around but with the cobalt bit, I get nice long spirals if I get the feed rate just right - I don't know why, but I love seeing the long spirals of steel when drilling

I have a drill doctor and use it pretty reguarly to keep my HSS bits sharp but, as I mentioned, not had to use it with the cobalt bits yet.

I hope this is helpful for those like me who tinker with metal. If you expect to be drilling into steel, try a cobalt bit - made a world of difference for me.

[Steggy]

American industrial might was built with high speed steel. If it was good enough to build our battleships and combat aircraft, it is good enough to use in the average home shop.

[rkcarguy]

That drill press is too fast, but I agree the cobalt bits seems to perform better and last longer.
2005 thread!

[gwrdriver]

Let's talk about WD-40. Yes, it has hundreds of amazing uses, and you can buy it at the corner market, but does it have any lubricating qualities for cutting metal at all?
That's a serious question. I use a commercial cutting and tapping fluid. I've never tried to substitute WD-40. I've never even thought about trying it. Has anyone else? (And even if you have, successfully, I won't change from what I use.)

[tornitore45]

WD40 works for aluminum, keeps the Built Up Edge from forming.
Brown Cutting oil for steel
Dry for cast iron and brass
Someone mentioned milk for copper, never tried and never will.