Machining Titanium

Edited By Alf Jones on 30/10/2011 08:33:45

Yes you can weld Ti you need to have a gas shield that covers the back of the weld as well as the front,

you will also need gas to cover the heat affected zone until it is cool you will need a good quality T.I.G welding M/C. Machining treat it like cooper for speeds and feeds, tapping if say you are tapping a 6mm thread drill size would normaly be 5mm I would go for 5.2mm drill using a machine tap and a thick cutting compound helps take it very easy clear the tap often of swarf .As for cutting fluid water based cutting fluid is best and plenty of it, also When cutting Ti if you use carbide tips the carbide absorbs Ti after a period of use I got near to size with H.S.S tooling and changed to carbide

Hi,

One small comment on the machining is that it is counter intuitive. Think of doing big slow cuts, if things start to get hot go deeper on the cuts. If you go for shallow cuts you will end up with bits of burning powder.

Tim

Alf

We had one shop which worked exclusively in Titanium. There was a very strict anti fire policy and there were special fire extinguishers everywhere. All the staff were specially trained as firemen.

What I am saying is be careful and clean up very well every day and put the swaff and dust well away form anything you care about

Rdgs

Dick

Alf,

I agree with Graeme on the size of the tapping drill i.e 5.2mm, if you have difficulty

tapping titanium you could try using 2 stage taps.

As an aside you can also electron beam weld titanium, but it would be very expensive

Colin.

"*ANY* advice sought"

To prevent heat buildup in Aluminium, (stickyness and clogging) I used my backgear

For a material like stainless though, you would need exceptional power, stiffness and hardness

Collin, I would suggest using a larger size tapping drill, and cutting thethread in one go, to cut in two stages invites work hardening on the first cut, and difficulties with the second tap. Just my small expiriance when tapping stainless steel, similar problem when using a die on stainless and trying to take it down in stages. Ian S C

Ian, Way back in the eighties I worked for a firm that produced components for the

oil industry. These were manufactured from titanium and had numerous tapped

holes ranging from m3 to m6, and as you can imagine we had a heck of a job

tapping them. The firm got a rep in from a specialist firm for advice, and he reccomended

the two stage taps. It was still a "cork in the bottom " job to tap them, especially the m3

but it was definitely a lot easier.

Colin

Surely the "super hot steam" won't be hotter than petrol vapour burning with air? Why not use aluminium alloy for the block with inserted liners made of steel or meehanite? It sounds from everyone's experience above that titanium will be an absolute b***h to machine with no end of opportunities for things to go wrong.

but one of the elements is an engine, likely a V-twin, dealing with super hot steam, in a situation where weight is a major issue.

Thanks Colin, Its good to get the info from someone who knows, I'm teaching myself, and finding out how as I go.

If weight is so important, is the motor for an aeroplane? Ian S C

It would definitely help if we knew its purpose, there's a lorra braincells and experience in this place

have machined a lot of Titanium in my time, mostly grade5, and on serious machines, would not recommend it as a material for engine blocks and Ti-Ti rubbing is an absolute no-no.

Have recently cut plate with an angle grinder, the fire aspect that was mentioned earlier was not an issue. In fact it cut better when the plate glowed red.......the sparks are ridiculously hot though and burnt a hole in my trousers and jacket......

Tapping is a nightmare unless you use cobalt style taps and drill at least Ø5.3mm for M6. Work hardening is not an issue but heat transfer is. Titanuim absorbs heat slowly so your cutting action will cause the immediate area to swell and expand and will "grab" your tool with a heart-stopping squeal. Don't try to force it - instead, go and make a cuppa and by the time you return it will be loose enough to retract.......then get another tap......

If you burn a drill out in the metal you are stuffed. The work hardening mentioned earlier is akin to a chilled casting. Cut low revs, feed hard and plenty of lube, pecking every 2-3 seconds maximum.

Have fun.........

Trevor

Only used titanium a few times but I agree with the above. The heat doesn't distribute anywhere near as well as steel or aluminium, it stays local for longer.

It would be interesting to know why the weights so critical is it for an aircraft? Something like HH Groves steam driven aircraft.

As a user of high temperature steam (engine steam feed pipe glowing) and always having to keep weight down due to regulations could there be an alternative to titanium to reduce machining problems.

There are ceramic coatings on aluminium pistons on one fullsize flash steam engine I know of and maybe other applications it can be applied to.

Experimenting is great when it all comes together.

Paul

**LINK** I work in a company that make and assemble these and have also machined some of the parts on them. Tapped holes range from M2 to M6, this is grade 2 titanium and machines like mild steel to a fashion. We weld these together too and again, not a problem - TIG with argon shielding. Hand dressing was easily done but quite labour intensive.

Andy.