Dealing With A Huge Piece of Titanium.

P

Polished Zirconium.

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Dec 26, 2015
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Hey everyone, massive machine and tool rookie here. Never even touched a mill or lathe before but I know a little about machining. Currently I'm going to a university with a nice machine shop that has a few people who work in it that have been machinists for a very long time and really know what they're doing so I'll be able to learn most of what need to know from them. However, they've never worked with titanium before, so I'm going to need some advice on tools and feed rates and such. I've got a few big questions:

I need to cut a 1" thick piece of titanium stock that I bought. It was really cheap ($60 for 1x3x9" 4lb block) and now I've got no clue how to deal with it. I was thinking of getting a carbide tipped bandsaw blade and trying that out but I also have a company who can cut it with a waterjet for me (however that is not cheap). Is a bandsaw going to work with a 1" thick piece?

What is the best endmill and tool material? I know Ti----- coated tungsten carbide Is the best, but I've heard that in some cases modern PM steels are better. Should I bother looking for maxamet (just an example) end mills or just go for ti coated carbide?

Assuming I end up using carbide tools, what sort of feed rates and cutting speeds should I use for milling titanium?
 
I would use a very new and/or sharp Lennox 14 tpi blade with the slowest speed available on the saw. A quality HSS endmill ran slow rpm, medium feed rate, and no more than a .020 or .030 depth of cut works nice for titanium. The key for me was tooling had to be SHARP, and I preferred a cutting oil instead of coolant when on the mill. Also only use less than half the endmills diameter and climb mill around the edges. It's a lot like 304 stainless.
 
Uhh well, I'd personally not try to process that with anything finer than 3-4 TPI blade. If it's 6al4v, you're going to wish you were using carbide tooth blades.


How are you trying to cut it? I mean, what are you hoping to accomplish? If you just want to cut it into smaller blocks or take slices off some dimension, use a horizontal saw, the bigger the better, and preferably yes, carbide tooth blades.


As for machining it, tooling will completely depend on the machine and task. If you're milling some feature on a manual mill, without flood coolant, then you want to use AlTiN coated end mills. If you're machining with flood coolant on a VMC, then you may want a different coating. All of this also depends what size class of machine we're talking about.


You're asking too general a question honestly. Generally though, as very basic guideline, slower speed, but higher feed, than steel. You need to take aggressive cuts, especially with 6al4v. However, considering you're jumping into very deep water, without knowing how to swim, you should definitely expect some failures, and lots of broken end-mills, until you get a hang of it. I'd seriously question the capabilities of anybody you're asking for help, that can't answer these questions on their own, titanium is different to machine than other materials, but anybody that's been responsible for determining efficient process for machining steel parts, should be able to quickly and easily come up with the starting point for titanium also.

Alloy is a huge factor, just like steel however. Cutting 6al4v as opposed to CP/Grade 2 titanium, is like the difference in cutting high nickel alloy tool steel, vs mild steel, they're extremely different beasts.
 
javand said:
Uhh well, I'd personally not try to process that with anything finer than 3-4 TPI blade. If it's 6al4v, you're going to wish you were using carbide tooth blades.


How are you trying to cut it? I mean, what are you hoping to accomplish? If you just want to cut it into smaller blocks or take slices off some dimension, use a horizontal saw, the bigger the better, and preferably yes, carbide tooth blades.


As for machining it, tooling will completely depend on the machine and task. If you're milling some feature on a manual mill, without flood coolant, then you want to use AlTiN coated end mills. If you're machining with flood coolant on a VMC, then you may want a different coating. All of this also depends what size class of machine we're talking about.


You're asking too general a question honestly. Generally though, as very basic guideline, slower speed, but higher feed, than steel. You need to take aggressive cuts, especially with 6al4v. However, considering you're jumping into very deep water, without knowing how to swim, you should definitely expect some failures, and lots of broken end-mills, until you get a hang of it. I'd seriously question the capabilities of anybody you're asking for help, that can't answer these questions on their own, titanium is different to machine than other materials, but anybody that's been responsible for determining efficient process for machining steel parts, should be able to quickly and easily come up with the starting point for titanium also.

Alloy is a huge factor, just like steel however. Cutting 6al4v as opposed to CP/Grade 2 titanium, is like the difference in cutting high nickel alloy tool steel, vs mild steel, they're extremely different beasts.
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Ok for the saw, that shouldn't be too difficult. They have one and I can get a carbide tipped blade relatively easily.

Yeah its 6al 4v, I should have specified. The reason I want to cut it is to separate it into different billets so that we aren't wasting a ton of material and putting a bunch of stress on the endmill trying to mill out a handle or two from such a large piece of stock.

As for the bits, I think I'll contact the company that the shop gets their tooling from for recommendations.

As for the people that work there, they know their stuff I just haven't spent a whole lot of time to talk with them about tooling and stuff like that. I haven't asked them these questions since they are quite busy and I didn't want to bother them with stuff I could learn elsewhere.

As for not knowing how to swim, that's definitely what I plan on learning first! I just want to have a plan laid out for this so once I feel comfortable with the machines and other materials will be able to jump right in rather than having to wait weeks to get all the tools I need and such.

Thanks for the tips!
 
Carbide endmills, stick around .001 per tooth, increase or decrease with size. Example ,.25 endmill ... ,0007 per tooth works well. I also can't recommend gwizard enough. Maximize your cutting and tool life. I broke tons of endmills before I got gwizard. Still break some, but usually after they have dulled
 
Make sure you do some research on safety ! Fire prevention .Keep the machining area clean , always .don't let chips and grinding dust accumulate. Have fire extinguishers designed for Ti and training for employees !
 
Ti can be a fire hazard .Keep work areas clean , always ! No chips or grinding accumulating. Get special fire extinguishers and train workers !
 
I can tell you what I work with, but it won’t help. Because the cost wouldn’t be comparable to sending it to get it cut with the jet.

I use an 8 PCD insert end mill from Sumitomo, on an Enshu 450 CNC with S5000, F1000 to remove 0.300mm it give me 5,000 life cicles.
5oi1du.jpg


I must keep a max tolerance of 0.025mm for overall face flatness it is measured on a Zeiss CMM.

34sqsu9.jpg


Just the endmill is $3,976 USD and is delivered in 70 days so I would say: Go for the water jet. Definitely Ti stuff is expensive in part because Ti is expensive but mostly because the right tools are VERY expensive.
 
mete said:
Ti can be a fire hazard .Keep work areas clean , always ! No chips or grinding accumulating. Get special fire extinguishers and train workers !
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This! Definitely! Years ago I was counterboring a piece of Ti for a frame lock scale with a HSS counterbore and had a small pile of fine shavings on the bed of my mill. I was using lubricant and still managed to catch the mill table on fire. It went out quickly but scared the poop out of me.
 
On the milling side, CrN or ZrN coated tools work best. DO NOT use any tools with titanium in the coating (TiN, AlTiN, TiAlN, etc...). Those coatings allow the titanium to bond to the leading edge of the tool and break the edge down very quickly.

If you can't get a CrN or ZrN coated tool, use uncoated tungsten carbide, M42 Cobalt HSS, or T15 HSS. The tools must have sharp edges and positive rake. M42 & T15 HSS gets sharper than carbide and often lasts just as long in titanium.

Titanium work hardens very quickly. When you start a cut, commit to it and keep going. Don't dwell or try to stop and restart. This goes for milling, drilling or sawing. For feed rates, it's always best to ask the manufacturer of the tool. In general, feed rates for aluminum usually work well on titanium (although you'll need the horsepower to support it). Best to keep a heavy chip load, around .003-.005''/tooth, to avoid work hardening. This all comes down to how it's set up & fixtured, and what kind of machine you're using.
 
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