Turning titanium?

[cdhknives]

I am researching and reading everything I can find in preparation for a project where I will be making a lot of titanium chips. Everything I read says light ribbons are the worst for catching fire, but I have little confidence in taking heavy cuts with my 10F, and finishing cuts will always be light. I also see recommendations for low speeds. I do not have a flood coolant system...only regular cutting oils that I can brush or drip on before a cut.

What can I expect from Grade 5 and 9 Ti? What are reasonable RPM and feeds? I have 1.25"OD round bar and 1.25"OD tubing. The round bar will be turned into cone baffles for a suppressor, so drilled, bored, and turned down a lot...call it 85% into chips.

 

[bakrch]

It's pretty easy to turn and bore, drilling can be "fun" though (not).

Turning, I like to stick with 180 SFM and .002 IPR using the sharpest carbide insert that I can find (CNGP usually) ... biggest radial cut you are comfortable taking on your machine will be okay.

Keep the chips from accumulating in the bed, and then titanium fires just become an "oh look, another one" event. If you have a large pile of chips that can ignite from that, yeahhh ... then you might have a problem.

Bring drills out often, keep them cool or the flutes will get choked out due to chip smearing. I generally stick to carbide tipped drills and let the drill move at its own pace. Hurrying things will just kill your tool.

 

[Aaron_W]

Class D fire extinguishers for metal fires are quite expensive compared to regular ones ($600+ for a 30lb) but you might be able to get a couple pounds of the powder from a fire extinguisher service. A lot of the extinguishing agents can be applied with a scoop and you are probably looking at a relatively small quantity of titanium.

Titanium only requires the standard Sodium Chloride based Class D agent, not one of the specialty copper or graphite agents like some of the more exotic combustible metals.

A standard ABC fire extinguisher is ineffective on metal fires, so it might be worth having a way to deal with a fire in your chips.

 

[pontiac428]

Class A+D extinguisher = a bucket of sand (for the home shop, at least). Like Aaron_W said, keep your fuel load down by cleaning your chip tray often. I would rather vacuum sand from my chip tray than to decontaminate a mess of salts from my machine from an extinguisher.

 

[wa5cab]

What machine are you using that can get down to 0.002 IPR? And what Depth Of Cut are you using?

 

[bakrch]

What machine are you using that can get down to 0.002 IPR? And what Depth Of Cut are you using?

PM 1236. B5 SI setting with the change gears as it came from the factory.

.05 to .07 per side is where I like to live on my lathe. Double that cut on the Mazak I have at work. My PM will make the big cuts with a new insert, but isn't long before the wear catches up and wants to stall the spindle. This all 2.5" diameter and under.

 

[cdhknives]

There's a 'rub'...I am running an Atlas 10F, hence my post in the Atlas forum for what to expect when using my lightweight Atlas on titanium. Without special gearing I can't get that low IPR, for example, and don't have the rigidity to take heavy cuts even with a good AXA toolpost and heavy (A11) cross slide.

 

[wa5cab]

The 10F will get down to 0.0027" according to Part 7, Table II. However, it requires a 56T gear that doesn't normally come with the lathe. And three bushings, bolts and sleeves. Three originally came with the lathe but as the standard configuration that most will be with uses only two, the third set may have been lost.

The QC versions (10" and both 12") can get down to .0021" by introducing a 2:1 reduction before the final 48T gear on the banjo.

 

[jhinze1970]

The QC versions (10" and both 12") can get down to .0021" by introducing a 2:1 reduction before the final 48T gear on the banjo.

for those of us mathmetically challenged can you provide an example of what you would place and where? I'm assuming you'd loose the low thread range and QCGB would essentially thread 8tpi and up?

 

[wa5cab]

Do a search for
12" Commercial Reduction gearing
in this forum. Scroll all of the way to the bottom and then back up a few posts. As you will see, there are several solutions but if you have no extra gears or spacers, you will see that regardless of whether you achieve the second 2:1 reduction with 40:20, 48"24 or 64:32, you are going to need a spacer and at least one new gear. But basically, you install the new 2:1 pair where the sliding gear was. The smaller gear behind where the sliding gear normally is drives the original rear 48T, which with a spacer in place of the original outer 48T drives the gear box.

To your second question, not exactly. Because the feed is exactly half per revolution of what it was originally, if set for 8 TPI, you will cut 16 TPI. And so forth. So if you need to cut less than 16 TPI, you will have to get your hands greasy and put it back to original.