TiN Coated Bits: Why?
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  1. #1
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    I see lots of companies selling Titanium Nitride coated (TiN)endmills, drillbits, and others. I don't understand how a coating will improve bit performance in the long run, since I would assume that in all the places where the coating matters, it'd get worn away and be useless very quickly. Can someone please explain the use of TiN bits and what they are useful for or if they're just a waste of cash?

    Thanks.

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    kennametal and carboloy have some TiN turning and milling inserts that total rip steel, sparks flying and cutters eating hard flame cuts.

    I did pallets full of flame cut circles and in the hard edge I got about 2 times the insert life.non TiN chips would crater much faster.

    why is it better? the TiN is slick and moves the heat away faster, I machine dry most of the time other than drilling and threading, reaming,. coolent would olny add to the tool life.

    think of TiN as slip and slide tool helper.

  3. #3
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    And TiN is the old stuff, much better out there now, look at some of the better tooling companies, they have coatings that kick ass.
    Bill

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    TiN coating is:
    1. Hard
    2. Slippery (as has been mentioned).
    If you ever use TiN coated tools, you will find that the coating doesn't wear off as quickly as you might think. We have a recurring molydenum job in our shop, .125 +.0006/-0" bore (moly is VERY abrasive on tools). When I started working there, the owner used solid carbide boring bars... after 12-15 pcs, had to start tweaking the offset. I suggested we try the TiN coated bars; at 80 pcs., start tweaking, go to 100 pcs., and save it for another job. And, as Bill said, there are other options out there; I just can't find CBN coated (not plated) boring bars in the size I need!

    RAS

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    TiN coatings is a has been, but better than no coating.

    +1 Bill (Mr bridgeport). Coatings have evolved into some very awesome stuff... and it works too!

    Wait till you get into TiCN (also old news), TiAlN, TiNAl, Diamond, etc, etc... then cryogenic tempering....

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    Ah, yes, TiCN. Talked the boss into TiCN coated drills for the initial .120 hole. Went from 60 pcs. to 200, on one drill bit. I wouldn't say these 'old' coatings are "old news"; they have their place in small shops, that don't have the $$ to spend on the more exotic coatings.

    RAS

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    TIALN coating it good stuff, TiN too, but I tend to think half of whats sold as TiN coating anymore amounts to some kinda gold paint lol. Cryogenics, hmm they havent' convinced me on that, I still think its somebody trying to make a quick buck with a shell game. Had some inserts and end mills done awhile back. I see zip difference in the life compared to non treated tools.

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    It seems that any import piece of crap is TiN coated these days, and about half of them seem to be more like CRS than HSS under the coating......

    I have started to avoid the TiN for that reason. In my home shop usage, it doesn't seem to help at all. Avoiding it when buying cutters seems to avoid the worst of the crap cutters.

    That would go in spades for drills......TiN, the wonder material....TiN coat your drill factory's scrapped-out drills and sell them for big bucks to the dumb-s$$t americans.

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    I wouldn't say these 'old' coatings are "old news";
    What I meant by 'old news' is that they've been around commercially for awhile. I still use them too.

    Cryogenics, hmm they havent' convinced me on that,
    I haven't seen any significant too life increase either. In theory, it should. But, if there were any, it was very small at best. The difference I have noticed is actually in tool stability and cutting stablility. It seems to increase the performance in X-tra long apps, either in LOC or or neck back. I'm still testing this application. No real impressive results though. I'm leaning towards the direction of improving harmonic balance (rigidity and chatter). Also have noted some improvement in corner rigidity and integrity.

    Haven't given up on it yet. Will let you know if anything exciting comes up.

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    It seems that any import piece of crap is TiN coated these days, and about half of them seem to be more like CRS than HSS under the coating......

    I have started to avoid the TiN for that reason. In my home shop usage, it doesn't seem to help at all. Avoiding it when buying cutters seems to avoid the worst of the crap cutters.

    That would go in spades for drills......TiN, the wonder material....TiN coat your drill factory's scrapped-out drills and sell them for big bucks to the dumb-s$$t americans.
    So why not just stick to the same brand?

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    Works out that way, but not everyplace has every brand, and the 'same brand" doesn't make everything.

    Plus, I ain't destitute, but I am not so rich as not to care. I'll buy a different good name on sale if available.... I can't write off stuff like you do....no business expenses in my shop.

    More just a pointless rant on the new thing of TiN being a "magic value adder" when it often just seems to cover over the junkyness of junk....not that my opinion would change anything....

    It must be that gold color...can they put it on faucets for those yuppie marble and gold bathrooms? TiN coated pot metal.....ooooohhhh.... how to improve zamac.... Atlas owners look out......

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    More just a pointless rant on the new thing of TiN being a "magic value adder" when it often just seems to cover over the junkyness of junk....not that my opinion would change anything....
    its like those chocolate covered ice creams, you can have a hard shell (TiN ~ 3000vpn)but if the substrate is soft it won't stand up to much... for a good ballance on ROI i'd go for 8%cobalt HSS rippers with a TiCAN coating and 10%micrograin carbide TiAlN coated for finnishing for general jobbing shop/low volume work. the extra dry lube type coatings tend to ramp up the price but for dry machining they lower the heat build up/transfare to cutter substrate/component

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    Funny story about TiN coating. The company I was at last summer sent out some parts to be TiN coated, sent 'em to a place that does coatings as their specialty. I think that's all they did. Anyway, when we got the parts back they were a nice shiney silver color.

    Yes, that means what you think it does. The morons had coated the parts in tin. The metal. I kept wondering how on earth could those people believe that we wanted the parts tin coated--do I look like one of those kiddies who CaPiTaLiZes EvErY OtHeR LeTtEr? It was written TiN for a reason!!

    -Justin

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    How did cut?

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    What do you folks think of Zirconium Nitride coated drills?

    I ran a small and very subjective test on a couple of 1/8" drills - TiN and Zirconium Nitride coated drills driven by a good quality 3/8" variable speed drill motor.

    Drilled probably a couple hundred holes in 1/8" cold rolled on a 32 Ford reproduction frame.
    (The job was what is called "C'ing" or notching the frame in the rear for added clearance before the rear axle bottoms out.)

    With no Plasma Cutter and not caring to use an Oxy-Acet rig for cutting, doing the old drill a few hundred holes, connect them with a small and sharp cold chisel to knock the piece out and then using a drum sander to smooth it out was the preferred method.
    It worked well and didn't take too long.

    I ran both the TiN and Zirc coated drills and they seemed to do equally well.
    An uncoated HSS drill (USA made) didn't do well at all when compared to the coated drills.

    All drilling done dry.

    One small, but interesting thing learned was to use the fluorescent lights in the shop to set the drill speed.
    If too fast, the flutes appeared to revolve one way and too slow, the flutes appear to revolve the other way.
    The right speed had the flutes appearing stationary.
    Never really noticed that before, but drilling a few hundred holes in an afternoon gives you time to think about things....

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    I have mixed feelings on coatings, I've used some incredible inserts that were coated, TiN TiAlN etc.., but then you'll get a different grade from the same manufacturere with the same coating and it shatters in 30 seconds, the underlying substrate has a lot to do with it, the ice cream thing.

    Another odd one, nasty high nickel alloy running C-2 carbide roughers, started with TiAlN coated, worked pretty darn well, one salesman suggested that maybe we might want to try the uncoated since the temperatures that the carbide endmill is brought up to get the coating to adhere will slightly dull the edge. Sure enough, we kept farely close tabs on the tool life and the exact same endmill, on average gave about 30% better tool life uncoated. Now this was at 100-130 SFM bump up to 2-4000 in aluminum and I'm sure the lubricity of the coating will make a difference. Just something to keep in mind, though another salesman said that was crap and the reason the endmills were breaking was that we weren't running them fast enough to make the coating "work". :rolleyes:

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    For me, TiN coating helps the most on finishing. Can usually take finish cuts on 8620/4140 etc. at 500-1100 sfm, depending on depth of cut, feed. I only get a little more sfm out of them for roughing, or the coating wears away too fast, then the insert with it. Never got to try any of the fancy TiALN, TiCN, etc. This is on manual machines, not CNC, where those cutting speeds are probably normal for rough cuts.

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    "It must be that gold color...can they put it on faucets for those yuppie marble and gold bathrooms? TiN coated pot metal.....ooooohhhh.... how to improve zamac.... Atlas owners look out...... "

    LOL!!!

  19. #19
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    ust something to keep in mind, though another salesman said that was crap and the reason the endmills were breaking was that we weren't running them fast enough to make the coating "work".
    I've witnessed some truth to this with TiAlN. Had alot of jobs where we switched coatings and didn't really see a noticable difference in tool life. Was told by a salesman (who I've known for almost 20 years and actually trust) that the coating likes heat and will increase in lubricity as the temperature rises and will work better. We doubled the surface feet, slight changes to the program... He was right, tool life jumped 3x longer.

  20. #20
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    the choice of tool material and its coating/uncoated, depends on several factors. basically the tool needs a good ballence between hardness, abrasion resistance, ability to keep its edge when heated and sharpness. to look at each area in turn; hardness is the basic ingreadiant...the tool needs to be harder that the work, but too hard the tool is brittle so toughness also comes into it. closeley related to hardness is abrasion resistance (a hard material is not always that abrasion resistant, a pencil is a good example) coatings being >3000vpn give a higher surface hardness. hot hardness comes next...because as the tool cuts it generates heat... the ability to withstand this heat or ability to not absorb it by some means is a real bonus...coolant unless copiously applied can have a negative effect on the cutter, whilst the coolant removes the bulk of the heat, if it's not applied in sufficiant volume the coolant boils at the tool cutting edge causing thermal shock and cracking in the cutting edge microstructure, some of the latest coatings lower friction (e.g. Zirconium)and thus lower the overall heat build up. sharpness plays more than a minor role in cutter design and affect all the previous, basically for a new tool, a sintered carbide insert with a PVD coating i as blunt as you'll get for new, let me explain...inserts are made by powder metalergy, they are isostatically pressed in a mould and then heated to fuse togeter all the particals... if you look at the insert edge under a 20x lens you'll see that is kinda rounded off i.e. BLUNT, now if this is then coated its like wraping cardboard over the corner of a table... the card corner is even more rounded!! a blunt tool generates more heat and more rubbing (abrasion) so on some levels the cutter design is self defeating. to counter this effect ground inserts can be aquired, these are often ground using a D150 diamond wheel, but under that 20x lens you would still see a very rough edge, hear is where HSS is better... it can be honed to a keener edge (think of the barber who sharpens his cut throat razor on that leather strop)but HSS has not got the benifit of hot hardness that carbide has... a good compromise hear is the often overlooked ultra high cobalt tool steels (i.e. 30-40% Co)such as Tantung or Stelite...anyway after all this ranting my final conclusion is...look at the cutter manufactures data... use the cutter they recomend for your application i.e. take into account if it's a roughing operation, intermitant cutting, finnishing cut, material type etc...don't forget if you use coolant...use pleanty of it...also follow the recomendations on speeds and feeds (don't be scared)but also take into account that they will have tested thier cutters on the best possible machines under the best conditions so they can publish bigger numbers than thier competitors so go for 30-50% less and creep towards thier recomendations. stick with the better known brands and if the data is not available you can always get it from another book and go a bit less than recommended


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