[handlewanker]

It's a poor conductor of heat, which is why tooling melts in seconds if the coolant isn't adequate.

True, but I think the high melting point and the non oxidising properties would make a crucible very acceptable......I doubt that heat would not penetrate to any large degree to the inside of a container if the walls were quite thin.

I was quite stunned at the "tooling melting in seconds etc" statement as I was not aware that Tn was that hard to machine without coolant...….I machine stainless without coolant frequently although that stuff is not hard by any stretch, neither is Tn......so at a reasonable RPM what makes Tn so dodgy for turning?
Ian.

[Zorbit]

I was quite stunned at the "tooling melting in seconds etc" statement as I was not aware that Tn was that hard to machine without coolant...….I machine stainless without coolant frequently although that stuff is not hard by any stretch, neither is Tn......so at a reasonable RPM what makes Tn so dodgy for turning?
Ian.

The heat generated when cutting goes four ways, into the job, into the swarf, into the tool and into the coolant. Ti is a poor conductor of heat, so little goes through the job or swarf. If the coolant is inadequate that leaves the tool. A HSS centre drill can die in seconds.

Specialists often use high pressure coolant pumps, but I haven't got one.

There are other properties that I can't explain, particularly the way it tries to deflect away from the tool unless it is really well supported. If you turn some on a conventional lathe you need absolute minimum stick out from the chuck and really sharp tooling or your job will not be round.

Lastly, there's the swarf. Nasty sharp and strong, it wraps around the job if you don't hit the sweet spot of feeds and speeds and even then you can make ten parts fine and then the 11th will be a birdsnest. It tends to be long straight swarf rather than the tight curls you get from 303 stainless for example.

However, when you get it all right it's a really useful material.

[Zorbit]

I googled this handy guide from Sandvik:

https://www.sandvik.coromant.com/us/news/technical_articles/pages/troublesome-titanium-tips-on-machining.aspx?Country=gb

Troublesome Titanium - Tips on machining this tough material



One of the lightest metallic elements in the periodic table, titanium is also among the most important. Without this durable, high-strength material, our world today would be a far different place. Airlines would charge more for flights, houses would need painting more frequently, hip joints and dental implants wouldn't last. Unfortunately, the same characteristics that make titanium ideal for a wide range of aerospace, medical and consumer products also make it an unwelcome visitor in many machine shops.
?
1. The Basics
Titanium has a narrow band of machinability, with recommended cutting speeds of 60 m/min for roughing and 3-4 times that when finishing. Feedrates are entirely dependent on chip loads and other factors, but should be high enough to prevent work hardening. Significant deviation from titanium's feed and speed comfort zone can mean melted or broken tools and a pile of expensive scrap. Follow cutting tool manufacturers recommendations and don't be afraid to phone a friend if you get into trouble.

2. Hot Stuff
Titanium conducts heat at about the same rate as the hot pad you use to pull a cake pan out of the oven. During machining operations, this poor thermal conductivity traps heat in the work zone, wreaking havoc on cutting tools. If your machine setup can handle the additional load, try increasing the feedrate to push some of that heat into the chip and make tools last longer.

3. Tough as Nails
If steel were stiff modeling clay, titanium would be frozen Silly Putty. Built-up edge, notching at the cut line, galled workpieces and chips welding to the cutter are the primary failure modes when machining this gummy material. A positive rake cutting tool with a tough substrate and hard, lubricious coating keeps tools in the game longer. Also, a small T-land or slight hone on the cutting edge can help improve tool life, but don't overdo it—titanium needs a sharp tool.

4. Keep it Cool
With the high heat and stringy chips generated when cutting titanium, a copious flow of clean cutting fluid is essential. Filtration to 25-micron or better is a good idea for many machining operations, but is especially important with critical operations such as this. Increase the coolant concentration to 10 percent or more, and install a high-pressure pump of at least 500 psi to blast chips out of the work area. Always use coolant-fed cutting tools, and employ inserts with aggressive chip control to avoid catastrophic re-cutting of chips



5. The Right Stuff
Because of the extreme cutting forces involved, titanium should only be machined on rigid equipment. A machine spindle with abundant surface contact at both the taper and the face used together with CAPTO holders provide the security of multiple contact points with the machine spindle, excellent repeatability, and the stiffness needed to absorb heavy radial loads. Dense machine construction will absorb vibration and cutting loads better than one designed for light duty machining. Don't even think about running it on that old lathe sitting in the corner of the shop, the one with the sloppy ballscrews and whiny bearings. Likewise, machining titanium on commodity equipment yields results similar to entering the family mini-van in a stock car race. The bottom line is this: invest in a high-performance machine tool if you're serious about titanium.
6. Hang on Tight
Titanium tends to grab end mills under heavy loads, pulling them out of the toolholder. This leads to scrapped workpieces and broken tools. Some shops turn to Weldon shank holders as a way to secure tools, only to find cutter vibration loosens even the most tightly torqued setscrews. Shrink fit holders are a good choice, but require some small investment in an induction heating station for tool changing. For a no-fail grip, a Safe-Lock or equivalent system secures toolholders tightly and accurately. Hydraulic holders like the Sandvik Coromant CoroChuck 930 utilize the latest technology and will prevent pull out. On the workholding side of the equation, a hydraulic vise with hardened and ground jaws is the best bet for clamping titanium parts—a serrated or knife-edge jaw gives an extra bite during roughing operations.
7. Programming Techniques
The right toolpath is a big part of success when machining titanium. The same techniques as those used in high feed machining (HFM) are effective here. Roll into the cut and don't slow down in the corners. "Drive" the cutter around the corner by using programmed radius cutter movements. Trochoidal milling paths with constant cutter engagement lessen shock to the machine tool and cutters alike, extending tool life. And plunge milling can be an effective way to rough out deep cavities.

8. Be Strategic
Above all, develop a sound machining process before the first chip is ever made. Analyze all of the part features, taking special consideration of unsupported areas, tall and/or thin walls and hard to reach features. Plan your moves more carefully than a sophomore sneaking into the senior prom dance. Pick the right cutters, set the appropriate feeds and speeds, and then generate code that meets the conditions mentioned earlier.

Granted, these are general guidelines. Titanium presents a complex machining situation, one whose cutting parameters depend on the size and geometry of the workpiece, the specific alloy being cut, and the rigidity of the setup and the machine tool. Probably the best tool available for successful titanium machining is to contact your cutting tool manufacturer or equipment provider knowledgeable in this area—best of all, it's free.

[peteeng]

Hi - Ti's heat conduction is about 1/4 that of steel. So really depending a lot on the coolant removing heat. Its half the stiffness of steel (steel 200Gpa Ti 110Gpa) so deflects more as stated prior. It has very low plastic shearing character like Al. So this means it transfers itself to the tool very quickly which blunts the tool and then friction peaks and everything goes awol. Ti loves oxygen. So much so that if molten it will break down any available water (coolant?) or atmospheric water liberating hydrogen then this explodes. Even red hot Ti will absorb huge amounts of O2 given the chance. All round can be dangerous. Peter

[handlewanker]

Wow Batman, I thought Kryptonite was dangerous.....reminds me of my old girlfriend...….difficult to handle if you don't have the right equipment, likes to be kept well lubricated and cool, has a tough shiny outer layer if rubbed hard but is soft like a marshmallow on the inside and has to worked like a young buck with a good tool.....forget about the old geezer in the corner.

I have to wonder really what Tn is so good for given all the side effects that can age you, make your hair turn grey and deplete your bank account....personally I'll stick to stainless...…..I can't think of any real property that would justify as a really must have factor for a Tn solution, unless of course we're talking about fairly large components in very specific conditions like the space race scene or the boating fraternity.

Given the lightness and toughness I wonder how it would compare to magnesium alloys for the mag wheels so liked by the car industry......machining magnesium would not have all those problems.
Ian.

[peteeng]

Hi HW - Most "mag" wheels on the street are actually aluminium and machine very well thank you. Real magnesium wheels as used in F1 and Indy etc is just as bad maybe worse then Ti. The emergency flares you see use magnesium dust as the fuel. Oh and don't use a CO2 or a water extinguisher on the magnesium,. its hot enough to break it down to Carbon and O2 and further accelerate the fire!!

https://www.firehouse.com/operations...agnesium-fires

cheers Peter

[handlewanker]

UHH....that explains it, my "Mag" wheels are not Mag after all...…..a rose by any other name etc.

Would I be right in saying that under "normal" circumstances Tn has no real specific use or place in the amateur's workshop?
Ian.

[peteeng]

Hi HW - Ti and other advanced materials are great to play with as long as you read up on their correct processing. I certainly did not know much about it when I decided to made a couple of Ti bike frames. But you make, live and learn. Ti is great when high strength, low weight, corrosion resistance and pizzazz is needed. It has good hot strength so is used in car and boat exhausts. There are many alloys available for various applications and these days for small parts just design them and get them printed. Ti prints really well so is becoming the material of choice for lots of things if your going to print vs machine. Cheers Peter S

[handlewanker]

Hi....high strength low weight and 3D printable......hmmmmmm, supposing a 3 jaw chuck was in that field...….that would be easy to print without any machining needed...….the limiting factors of RPM would not be so critical in that case.

Most 3 jaw chucks in the 160mm diam range state that the rpm limit is about 2K....that is probably the iron models......I expect a Tn chuck would have other problems like wearability from dings and friction wear in the jaw seatings.

One question come to mind....can you grind Tn …..providing you can hold it without the mag chuck.

Also, what is the comparative cost of Tn sections compared to say mild steel or cast iron and would it be available in channel, H beam and angle drawn sections?

Hydrogen/Oxygen generators (HO) are commonly DIY made using multiple stainless steel plates.....could Tn be used instead for the plates as it's available in .004" thich foil strips on EBAY.
Ian.

[RCaffin]

Some of those 'rules' quoted by Zorbit reflect some ignorance about machining Ti. In particular, you do NOT need flood coolant - I machine Ti a bit and don't have flood coolant. Treat that bit as Sandvik marketing spin.

The underlying problem is that Ti is tough, and if you don't cut it properly you will heat it locally so it gets MUCH harder, immediately. Then you have a problem with your cutter. This is quite similar to SS.

If you have a sharp (but strong) cutter, have the right surface speed, and keep the surface of the cutter very lightly lubricated (MQL with olive oil), cutting and turning is not a problem. OK, remember that it is not as stiff as steel.

But if you cut too shallow or spin too fast or feed too slow, then the cutter rubs and heat is generated, and everything goes downhill very fast. I did accidentally drill some Ti once with a much too high feed rate (but an OK spin). The Z axis current went up and the spindle power rocketed, but it drilled fine. On a bigger machine those parameters could have been OK. You can NOT 'ease into it' the way you could with Al or brass; you must be a little aggressive at all times.

I note the recommendation for high performance machines and very expensive tool holders. Great vendor marketing, but I use a (good) set of Chinese E25 collets in a Kennemetal BT30 holder, and I have never had a cutter pull out. If it happens to you, I suggest you need to rethink how you run your machine. Mind you, machining Ti on a cheap flexible Chinese router could be a doubtful proposition.

PS: yes, you can grind Ti: a shower of white sparks. Be kinda careful though about starting fires.
PPS: 'mag' wheels are mostly an aluminium alloy with a bit of magnesium in the alloy, just as 'titanium' treggkijng poles are aluminium with a bit of Ti in the alloy. Deceptive or fraudulent advertising.

Cheers
Roger

[handlewanker]

So.…"if you cut too slow or too shallow".....that equates to a finishing cut, or is there another way to do that final few thou for a finish size?

I would think that grinding would be a shallow cut for all the grains that make contact and the speed......oh my, no wonder the sparks fly.

I get the impression that this is like cutting stainless....if you go too slow on the feed and without any coolant or lube you will work harden the material.....stainless doesn't like to be run too fast either.

One thing I have found and that is.....NEVER tap or ream stainless with a blunt tap or reamer......a definite recipe for a broken tool.

I've found that with stainless if you use sharp tools with a good top rake you are home and dry...….I would think this would also apply to Tn......one day I'll try it if I get a piece just to see the effects.

The other properties of Tn would be somewhat of a mixed bag for most users......doesn't transmit heat very well....what for?...….not very conductive of electricity...….so?.......very light......so's aluminium...…….very tough, now we're getting somewhere, but stainless is like that too......resists corrosion...…..so does stainless...….stainless doesn't cost an arm and a leg and is very freely available at most scrap metal dealers for pennies per Kg.

Hmmmmmm…..I think I have it, the very most useful attribute that would justify a Tn build....the humble teapot.

Having a light weight and low heat transfer means you wouldn't need a tea cosy to keep the pot warm and a tea cup the same.....drop it and it bounces back......how many tea mugs have I got with handles broken off.

The biggest draw back for Tn would be the difficulty to be able to work it with conventional methods which puts it in the too hard basket for practical everyday use...…..I mean for the average person wanting to make something with Tn as a material requirement.

I could think of a dozen uses for Tn that require toughness and lightness in one hit...…...aircraft propellers are just one..... IC engine pistons are another....both need to be tough but light as they move under extremely heavy conditions.....the list goes on.

I suppose you could glue Tn foil to the bottom of a boat as an anti fouling medium.....and what about a Tn electric car body.....so light and tough.
Ian.

[mactec54]

True, but I think the high melting point and the non oxidising properties would make a crucible very acceptable......I doubt that heat would not penetrate to any large degree to the inside of a container if the walls were quite thin.

I was quite stunned at the "tooling melting in seconds etc" statement as I was not aware that Tn was that hard to machine without coolant...….I machine stainless without coolant frequently although that stuff is not hard by any stretch, neither is Tn......so at a reasonable RPM what makes Tn so dodgy for turning?
Ian.

I don't know where that came from ( Tooling Melting in Seconds, I have been machining Titanium for many years off and on and it can be machined just like any other material and does not need coolant to be machined, Coolant is always better to use when machining any type of material, the only problem is Taping a thread in it with a regular Tap it work hardens when hand tapping so that is the only part that can be a challenge, but thread milling and thread cutting and normal machining is not much different than any other material

I have a stock of Titanium Rod from 3mm to 20mm diameter that I use for making Anodizing fixtures, this material was all left over for when I manufactured Medical parts

[handlewanker]

Thanks Mac....good to know it can be machined with intelligence like most metals.

Would the problem with tapping Tn arise from using taps that had been used previously on steel and were not too pristine as in they are actually quite blunt?

I have found that tapping a similar difficult metal like aluminium bronze requires taps and reamers that were dead new and sharp......any previous use on steel etc and you get work hardening and a seized in tap that breaks on withdrawal.

Back in UK in the 70's I did work for the Admiralty and they had aluminium bronze components which if you used not so new taps you got a trip to the broken tap extractor.
Ian.

[mactec54]

Thanks Mac....good to know it can be machined with intelligence like most metals.

Would the problem with tapping Tn arise from using taps that had been used previously on steel and were not too pristine as in they are actually quite blunt?

I have found that tapping a similar difficult metal like aluminium bronze requires taps and reamers that were dead new and sharp......any previous use on steel etc and you get work hardening and a seized in tap that breaks on withdrawal.

Back in UK in the 70's I did work for the Admiralty and they had aluminium bronze components which if you used not so new taps you got a trip to the broken tap extractor.
Ian.

You can get Taps just for Titanium but they too don't last very long, they get dull very quick thread milling even very small holes is the best way to do internal threads, all other machining is normally a speeds and feed adjustment to get perfection

[handlewanker]

I think I would have to have a very good reason to gravitate to Tn for a project......mostly I redesign around a problem and being retired now I call the tune.

I just can't think of any situation where Tn would be a must have factor in a home workshop environment...…..stainless will suffice for all those needs I think and aluminium will do for any situation that meets the need for lightness etc......machinability does not come into that equation.

On all counts Tn is just too troublesome to warrant a stock buy in although I might try some .004" Tn foil to do a test I have in mind, but stainless is also available too and is more user friendly.
Ian.

[Zorbit]

Someone better tell Sandvik they got it all wrong.

Iscar too. https://www.iscar.com/Catalogs/publication-2019/machining_titanium_05_2019.pdf

There a widespread belief that titanium is like austenitic stainless steel in terms of its machinability. This may be true when relating to commercially pure titanium and also, with some assumption, ?- or even ?-?-alloys; however, it is fundamentally wrong with respect to the treated ?- and near-?- alloys.
In general, titanium alloys (which we will refer to as titanium and specify their composition, grade and properties separately where necessary) are hard-to-machine materials and their machinability depends on various factors: chemical composition, hardness, method of treatment. The main difficulties in cutting titanium are the following: • Intensive heat generation leads to excessive adhesive wear of cutting edge. • Low heat conductivity results in poor heat transfer and slowing heat dissipation down. Therefore, cutting edge experiences considerable thermal loading. • “Springiness” of titanium due to low modulus of elasticity contributes to vibrations and worsens machining accuracy and surface finish. The mentioned factors significantly reduce tool life and affect performance. The averaged data in Table 2 allows estimating machinability of titanium compared with other groups of basic engineering materials. Table 2 - Machinability Of Titanium Vs. Typical Engineering Materials (Averaged Data)

And Kennametal,
https://www.kennametal.com/kr/ko/industries/aerospace-old/machining-titanium.html

And Makino, who have a range of "T Series" machines designed specifically for cutting titanium - 53 gallon per minute through spindle coolant pump ! I guess they haven't heard of olive oil ;-)

"Titanium Alloy Ti 6Al-4V If you are reading this white paper, it’s likely that you have either heard about or experienced first-hand the challenges associated with machining titanium. You probably know all too well that its unique characteristics combine to create a perfect storm of machining challenges!
When machinists refer to issues with titanium, they are often actually referring to a specific titanium alloy called Ti 6Al-4V (also known as “Grade 5” titanium). Ti 6Al-4V is the most common titanium alloy; it makes up about 50% of all global titanium consumption."

[mactec54]

Someone better tell Sandvik they got it all wrong.

Iscar too. https://www.iscar.com/Catalogs/publication-2019/machining_titanium_05_2019.pdf

There a widespread belief that titanium is like austenitic stainless steel in terms of its machinability. This may be true when relating to commercially pure titanium and also, with some assumption, ?- or even ?-?-alloys; however, it is fundamentally wrong with respect to the treated ?- and near-?- alloys.
In general, titanium alloys (which we will refer to as titanium and specify their composition, grade and properties separately where necessary) are hard-to-machine materials and their machinability depends on various factors: chemical composition, hardness, method of treatment. The main difficulties in cutting titanium are the following: • Intensive heat generation leads to excessive adhesive wear of cutting edge. • Low heat conductivity results in poor heat transfer and slowing heat dissipation down. Therefore, cutting edge experiences considerable thermal loading. • “Springiness” of titanium due to low modulus of elasticity contributes to vibrations and worsens machining accuracy and surface finish. The mentioned factors significantly reduce tool life and affect performance. The averaged data in Table 2 allows estimating machinability of titanium compared with other groups of basic engineering materials. Table 2 - Machinability Of Titanium Vs. Typical Engineering Materials (Averaged Data)

And Kennametal,
https://www.kennametal.com/kr/ko/industries/aerospace-old/machining-titanium.html

And Makino, who have a range of "T Series" machines designed specifically for cutting titanium - 53 gallon per minute through spindle coolant pump ! I guess they haven't heard of olive oil ;-)

"Titanium Alloy Ti 6Al-4V If you are reading this white paper, it’s likely that you have either heard about or experienced first-hand the challenges associated with machining titanium. You probably know all too well that its unique characteristics combine to create a perfect storm of machining challenges!
When machinists refer to issues with titanium, they are often actually referring to a specific titanium alloy called Ti 6Al-4V (also known as “Grade 5” titanium). Ti 6Al-4V is the most common titanium alloy; it makes up about 50% of all global titanium consumption."

If you have worked with any or machined Hardened Tools steels then Titanium is like machining butter no matter what the grade, as I said it's all about Speeds and Feeds when machining any type of materials like these, Speed equals lots of Heat with this material, so you would need a lot of coolant for your tools to survive

[RCaffin]

@Ian: it is Ti, not Tn. No such element as Tn.

I get the impression that this is like cutting stainless....if you go too slow on the feed and without any coolant or lube you will work harden the material.....stainless doesn't like to be run too fast either.
Exactly. Get it right and you are fine. Don't rub!

@Zorbit and others: yes, and no about the Sandvik advice. If you want to machine bulk Ti at high production speeds, you may need to take special precautions. But as you can read here, quite a few of us routinely machine Ti and Ti alloys withOUT problems, and withOUT heavy flood coolant. Practical first-hand experience beats vendor theory every time.

Intensive heat generation leads to excessive adhesive wear of cutting edge.
I have not seen this amount of heat generation when machining Ti 6Al4V.

Low heat conductivity results in poor heat transfer and slowing heat dissipation down.
Yes, Ti has low heat conductivity. Use sharp tooling at the right speed and feed and you won't generate all that much heat in the first place.

Therefore, cutting edge experiences considerable thermal loading.
Not seen.

For me, the value of Ti lies in it serving as a very light and much harder replacement for aluminium, while being able to handle very high temperatures. For a hobby, I make and sell ultra-light canisters stoves for extreme winter and high altitude conditions. This is one of my designs:
Attachment 436394
It is called a vortex burner and bright red is it's normal operating condition. Ti body and top and pot support wires, and aluminium parts underneath where they only get up to ~100 C. Click on the pic to get a larger version.

Cheers
Roger

[Zorbit]

I think we've been coming at this subject from different angles. I make Ti parts in batches of 500+, every couple of months, on a 9 axis mill-turn. Speed and quality are important, the part is turned, milled and drilled. Without flood coolant the tools will not survive at any practical speed, and there are plenty of other parts waiting to be made.

The only parts in this picture that I don't make are the strings and the self tapping screws:

[peteeng]

Thats a beautiful instrument & piece of work Zorbit. No more to say... Peter