Thread: TiN speeds

Hello all

I am considering buying a set of TiN milling cutters from a company that has been mentioned here called M&G products.
I have two questions;
1. What is the recommended speed for these compared to HSS?
2. If you have purchased these, would you buy again or did you find them false economy?

I am a hobby machinist in the early learning phase doing a bit of cast and mild steel stuff, plus occasional alloy.

Thanks

Steve

Hi Steve, Guys,

Only my opinion, others may disagree, I've not experienced any real benefit from specifically buying TiN coated cutters and drills. Whilst they are advertised as longer lasting and more hard wearing in a hobbyist environment I don't see any advantage ! In any case the moment you sharpen one, thinking mainly about drills here, you remove the coating anyway.

In the home shop coating will give no advantage at all except maybe a small reduction in aluminium clogging (maybe) you really have to running in consistent material all the time for tool life to really come into it.

Also as a new starter you will mangle these in new and exciting ways long before they go dull!

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Originally Posted by BaronJ

Hi Steve, Guys,

Only my opinion, others may disagree, I've not experienced any real benefit from specifically buying TiN coated cutters and drills. Whilst they are advertised as longer lasting and more hard wearing in a hobbyist environment I don't see any advantage ! In any case the moment you sharpen one, thinking mainly about drills here, you remove the coating anyway.

Resharpening makes no difference to the action of the coating. the coating does its work on the flute where the chip is pushing against the cutting tool. when you regrind a cutting tool you are only removing material from the clearance faces, which should not be contacting the work or the chips.

Father Xmas left these for me under the Xmas tree, supposed to be carbide - I'm assuming they are carbide but can't see any difference between them and my HSS cutters. I've been using them on my current projects - materials are 1020 and 4140 steel and Aluminium - like all new cutters they are great to use, I'm a retired hobby user and I have a flood coolant setup, I do not work my machines hard, there is no need to, time is not money in my situation. A typical depth of cut for say an 8mm cutter might be somewhere between 0.5 to 0.75mm, I don't have a tacho so can only guess the spindle speed. My machine has a 4 speed gear box and a 2 speed motor with VFD, I mostly use the 1:1 gearbox ratio (straight through) and vary the speed with the VFD which is 1200rpm at 50Hz (lo speed), for an 8mm cutter I had the VFD set for around 20-25Hz so I'm guessing about 500rpm. I don't have power feed so feed speed is also a bit of a guess, I just use what ever feels comfortable - the greater the depth of cut the slower the feed speed, it comes down to the amount of metal being removed - with these new cutters it seems as if just the weight of my hand is enough to push the cutter through. If I'm not milling a slot and just removing material from a face I try to select the cutter diam based on the width of the material being cut so I always have a minimum of 2 teeth (4 tooth cutter) cutting.
Once they get worn and start to blunt you will feel a marked difference in the amount of effort needed to crank the table in the X or Y direction and may also notice any burr on the edges will get bigger. My flood coolant setup is not only for cooling but to wash away swarfe/cuttings, so if you don't have a flood setup try to keep swarfe/cuttings away from the cutting edges ( a brush or compressed air) if you take a cut and need to back up before taking a second cut clear all of the swarf away before backing up - it will extend the life of your cutters. Average cost for each cutter is around $7 so yes they are cheap - but so far I would say they are good and worth the cost.

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Originally Posted by familyguy

Father Xmas left these for me under the Xmas tree, supposed to be carbide - I'm assuming they are carbide but can't see any difference between them and my HSS cutters.

....

for an 8mm cutter I had the VFD set for around 20-25Hz so I'm guessing about 500rpm.

In terms of identifying that they're actually carbide, if that's what you mean by not seeing any difference - go by weight. A 12m carbide endmill is noticeably heavier than a HSS one, even by hand.

And if they are actually carbide, that speed sounds way off to me (Especially with coolant), even if that was for 4140.

Having a look at this chart: https://www.the-carbide-end-mill-sto...nd-Speeds.html

4140 would be 350 SFM, which translates to over 3500 rpm with an 8mm endmill. Now there are many charts with many different SFM numbers on them, but going off the 10mm carbide endmill I've been beating on for a few years, this one is pretty accurate.

I was never overly impressed with that 10mm carbide endmill I bought to try out, it worked nicely enough to begin with, but it was never 'wow'. Seemed to become somewhat blunt rather quickly, and just wasn't really cutting that easily anymore, running at maybe 1000rpm on garden variety steel. Looked up some speeds for carbide endmills, and ended up discovering it seemed like it should be running at a bit over the 3500rpm max of my Bridgeport, and at 3500 rpm should be fed pretty bloody fast. So with some trepidation, and a full faceshield, I tried it. That was where the 'wow' happened. This 'blunt' endmill suddenly started spraying a shower of chips everywhere, and I was cranking the handwheel as fast as I possibly could, which still wasn't fast enough. Beautiful finish left behind too.

I haven't used a HSS rougher, or anything else to remove the bulk of my steel stock for years - I'm still using that same 10mm endmill, run flat out in the matter described above, no coolant. It's got a couple of chipped flutes now - still rips big piles of chips off in short order. Which is why I bought a handful of 12mm carbide endmills recently off Aliexpress. At about $20 per 12mm endmill, if they last anywhere near as long as that 10mm has, they'll be well and truly worth it. I chose 12mm because above that size the prices get less reasonable. 12mm should be noticeably stiffer than the 10mm I'm using, and should need a little fewer RPM to get it singing.

I still use HSS in aluminium - I can't even get close to the recommended speeds for carbide. Although I did buy a set of 3 flute uncoated carbide endmills designed for aluminium to try out at some point, not sure they'll go that well given the speed limitations.

To summarise - if you've got at least 2.5k rpm to use, from my experience 10 and 12mm carbide endmills are the most economical. I've burned up a fair few HSS endmills, as I hate wearing coolant - no need with carbide. Could set up an airblast to clear chips if desired.

If you've only got 1000 rpm, I'd personally stick to HSS, given the poor life and performance of the 10mm endmill I've been running at that speed - just not worth the cost (unless you can find sets that are the same price as HSS, in which case... maybe?). You could of course step up to a big enough carbide endmill to fit within your speed limitations, but even the Chinese ones rapidly get stupid expensive over 12mm, so not really economical....

Alongside a HSS 0.5inch cutter the 12mm carbide is around 6-7mm shorter and around 50% heavier so I guess they must be carbide - you never know with Ebay the seller may not know the difference between HSS and carbide, I always look to see what other things the seller has and if it's things like hair curlers, dog leads and aquarium thermostats then it is a reasonable bet that they don't know the difference, no disrespect meant to the seller.


I checked out the speed and feed chart, my max RPM is around 4K will be worth a try on some scrap steel and report - the coolant comment has a lot of truth, I mainly set it up as I do at times make carbon steel t-slot and dove tail cutters - they last a lot longer if they are kept cool.

Originally Posted by caskwarrior

In the home shop coating will give no advantage at all except maybe a small reduction in aluminium clogging (maybe) you really have to running in consistent material all the time for tool life to really come into it.

The rule at work is TiN is good on all materials EXCEPT aluminium; ally sticks to TiN, uncoated is better.

For OP, download the FSWizard app; it has all the info you need on feed/speed and a whole bunch more.

I tried a 10mm cutter through some unknown scrap steel, depth of cut approx 1.5mm, rpm approx 3,200, no coolant and it did indeed slice through a 60mm length not sure how long it took - around 5 or 6 sec and certainly well under 10 sec, small chips flying all over the place, no need for air etc. to clear chips, a small burr on either side of the cut that 'fell off' when I rubbed a file over it - the cut finish was good, the chunk of MS did get quite warm. I know the scrap steel is only MS - I had in the past arc welded it and the weld bead remained soft so I'm reasonably sure it is not any sort of carbon steel. It was impressive, don't know if I'll do it this way all of the time though.