Titanium

[John Taylor]

Got to ream and rifle two titanium barrels this last week. First time I ever saw smoke coming out with the cutter. I had to get a carbide reamer and it got very hot the last 1/2" because I had to shut off the oil to keep it from going everywhere. I installed a carbide cutter for the rifling cutter box, don't think HHS would have held up to well.Go little accordion shaped pieces of shavings coming out.

[warf73]

Milling tite requires alot of flutes(I've only used carbide cutters 6~8 flutes), tons of coolant, extremly slow RPMS, and snail feed rates . I've no clue how to cut rifling but would think the same would be required as milling it?

[leftiye]

I am impressed with your machine work. As a person who hasn't yet broke down and gotten, nor even coveted a fluted barrel yet (I'd as soon it were heavy), and considering that I don't wear out barrels, and considering the probable cost, I'll pass on titanium (unobtanium to me).

[smokeywolf]

I have always used slow speeds with moderate feeds and as warf73 said, "tons of coolant". Too much coolant is almost enough. Cutting titanium generates heat like nobody's business. If you're deep hole drilling, thru the drill coolant is almost a must.

smokeywolf

[rattletrap1970]

I'd be very interested in hearing how it shoots.

[thehouseproduct]

I've always been told supremely sharp cutters is the most important aspect of cutting TI......

[Nobade]

Armalite tried Ti barrels back when they were working on the original AR-10, and they all blew up. I filament would carbon around Ti barrels 15 years ago for a light weight machinegun project, and they all blew up. Ti has an amazing affinity for other metals when subjected to heat and pressure sufficient to break through the protective oxide layer on the surface. Like in the bore of a rifle. Be careful with those barrels.

-Nobade

[akajun]

Armalite tried Ti barrels back when they were working on the original AR-10, and they all blew up. I filament would carbon around Ti barrels 15 years ago for a light weight machinegun project, and they all blew up. Ti has an amazing affinity for other metals when subjected to heat and pressure sufficient to break through the protective oxide layer on the surface. Like in the bore of a rifle. Be careful with those barrels.

-Nobade

Id heard this too, from a S&W rep when I asked why the Ti revolvers had a steel liner for the barrel, He also said that a defense contractore make some artillery barrels from ti, when shot the spark shower that came from the cannon was very impressive and the barrells quickly turned to smoothbores.

[andrew375]

Here is a good article on machining Titanium.

The main issue, as you have experienced, is that heat generated by cutting goes in to the cutter rather than the chip. So it is mostly about controlling heat production. One property that is rarely spoken about is that, given the right circumstances, Titanium will ignite and burn in much the same way as Magnesium.

Any way good luck and let us know how you get on.

[Rick Hodges]

Back in the early '70's I worked in a machine shop making parts for the SST project. Unlike the Brit/French Concorde the SST was to be a new technology aircraft: Titanium structures instead of aluminum. We used slow rpm and relatively high feed rates. Drills and reamers were generally cobalt/steel or stellite (carbide was an abomination that would chip) that were made for us by Cleveland Twist Drills...our drills and reamers usually had twin coolant holes and we flooded the work with cutting oil from the inside out. Tapping threads was a nightmare, but the material took rolled threads nicely. Titanium was very hard on tooling.
Form tools were usually cobalt steel. Again tool life was limited and required constant sharpening. We were working in the infancy of that material in the aircraft industry. Perhaps the technology has changed since then, I don't know?

[smokeywolf]

Perhaps the technology has changed since then, I don't know?

Largely the same as the early '70s. In the late '50s my dad worked on the A-1 which evolved into the SR-71. They had to develop new cutter geometries for the mass machining of Ti. Because of exposure to caustic chemistry, many of the parts that I've machined had to be Ti. Deep hole drilling is the worst; especially without through the drill coolant. In addition to HS/Cobalt and Stellite, Tantalum Tungsten also works pretty well.

smokeywolf