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View Full Version : Might have to mill some Titanium next week



MotorradMike
06-10-2010, 08:26 PM
Hi guys:

One day I may help you guys, probably not with machining but maybe with electronics. Seems like mostly I'm asking questions.

Here's the deal:
I now work for a company who bought out my previous employer. My 3 month contract ends in 2 weeks. The work I've done for them thus far has not challenged me at all and I'm pretty sure they think they don't need me.
They did not renew the contract of their Crackerjack tool&Die maker and quite frankly, in that department, I'm the best they've got left.

They have a shop with pretty decent Chicom stuff in it. The cutters are crap but I'll be able to get a carbide one for this job if necessary. Minimally, I will buy a decent HSS bit.

The problem:
1/16" thick Titanium plate with 1/4" thick webs in it. I may be required to mill out a window about 4" x 6" for PCB access.
I've searched here and googled and have gathered the following:

Low speed is good(below 100 SFM)
HSS works fine
Don't be shy, work hardening happens fast.
The chips may catch fire. - bad news (Good safety tip)
Coolant not necessary unless you go too fast.

I will find out what the alloy is before proceeding. At this point I have no clue. The part sure is pretty though and was expertly machined with a CNC mill.

Any tips or tricks will be very much appreciated.

squirrel
06-10-2010, 09:50 PM
If its CP Ti stay away from it, if its 6V4 or pretty heavily doped use caution. Make sure you have a fire extinguisher that can handle buring metals. More than likely it will not go out and you will also burn up the machine. Reactive metals should be left alone unless you have PLENTY OF REAL EXPERIENCE, not an internet education.

Uncle O
06-10-2010, 10:21 PM
.062" plate(sheet) with 1/4" web....? is that a typo ?

Don't let it scare you off, I haven't worked with a whole lot of it, but what I have, has been of no big concern.

You are correct about it can work harden , don't dwell.
Mostly I have heard that the danger with fire is with a build up of fines...
don't let the chips pile up if you are going to work that much of it.
Keep sparks away from any fines that may be present.
Heat doesn't seem to transfer very well, tools will get hot.

Others will chime in.........

MotorradMike
06-10-2010, 10:50 PM
Thanks Squirrel, not sure what CP means.

Uncle O:
Not a typo, I just didn't want to say "billet" because it seems to set people off. The part has been machined from solid 1/2" Titanium. Most of it is now 1/16" thick, the outside flange is 1/2" off the deck and there are interior webs in my way that are 1/4" thick. I can clamp the flange to the table with the 'tub' facing up, most of the cutting will be in 1/16" with 1/4" webs encountered at times.

I have nothing to lose. If I demand the right cutter and fire extinguisher and impress these guys enough to call their Tool&die maker to confirm, I might still have a job. Then I can buy you guys beer!

quadrod
06-10-2010, 11:04 PM
I have very limited experience with some titanium, it turns well and will single point thread well, but drilling and taping can quickly become a nightmare. Use a very sharp drill if drilling.

tdmidget
06-10-2010, 11:27 PM
You seem to have the big picture. Yes work hardening may be your major problem. No fire problem unless you try to impress everyone by going too fast. Use SHARP high speed tooling, I recommend M42. Don't be afraid to change tools at the first sign of dulling.
Don't let chips accumulate. Coolant is not necessary.
CP means chemically pure and is not relevant here. It is only used in process items like plating racks. heat exchanger tubes, and reaction vessels.
Don't ever call any thing "billet" unless you know what you are talking about. "Billet" is an intermediate step in metal production. NOTHING is machined from a billet because it is not a finished product. Billets go to the rolling stands in bar and rod mills. A special billet, called a slab, is rolled into plate. Billets do not have the grain established and are actually castings, with no regard for stress or cooling, because it is intended to be reheated and rolled into a finished product.

huntinguy
06-10-2010, 11:31 PM
decent hss isn't going to cut it. It has to be very good quality, and sharp. Keep a chip load on it. As for 100sfpm... well, that all depends on the type of Ti. Some of the stuff floating around has hard spots in it. Don't let chips build up. make sure everything you use is compatible with Ti. It is possible to get some pretty bad chemical reactions.

Can't help beyond that, I just make sparks with the stuff :p

tdmidget
06-10-2010, 11:35 PM
If all you can do is make sparks, don't tell people how to machine it.

darryl
06-11-2010, 12:00 AM
I once needed to machine a slot 1/16 inch wide and 1/2 inch deep into the edge of some plywood. I didn't have a cutter that I could make fit the router, but I remembered I had this piece of titanium. Cut out a square and drilled a center hole to fit a router bit shank. The four corners I hacksawed into tooth shapes, then sharpened it up.

It seemed that it never really came sharp, but it cut about fifty feet of groove on that job, and didn't seem to get any duller. Anybody who has milled into the edge of plywood much knows that it's hard on cutters, most especially non-carbide ones. I still have it- that is one SMOKIN cutter- literally- and stink! Nothing like the stench of burning plywood resin and end grain cuttings!

Anyway, I found that it's easy enough to cut with a hacksaw, so it shouldn't be too hard to cut with a jig saw using a suitable blade. One with a blade kicker feature would be best, like one of the Bosch ones.

deltaenterprizes
06-11-2010, 12:23 AM
The Ti I got to play with machined like stainless with a carbide bit and I got a decent finish.

thedieter
06-11-2010, 12:56 AM
Check on what it takes to put out a Ti fire...I think it has to be smothered with sand so investigate that aspect.

Best regards, Jack

tdmidget
06-11-2010, 01:10 AM
I think the OP wanted to hear from people who have experience with machining Ti, not those who "think", "have heard", or have experience in plywood.

hitnmiss
06-11-2010, 11:08 AM
tdmidget,

A little harsh, this is a public forum and the answers given benefit more than the original poster. Knowing that ti cuts easy enough with a hacksaw might be beneficial to someone...

Maybe practical machinist is the forum for you.

boaterri
06-11-2010, 11:52 AM
Have a Class "D" fire extinguisher handy while machining. DO NOT USE WATER!

Good luck,

Rick

Please disregard, I was thinking of Magnesium. Sorry,

Rick

Dr Stan
06-11-2010, 12:43 PM
Have a Class "D" fire extinguisher handy while machining. DO NOT USE WATER!

Good luck,

Rick

Pay attention to Rick's post. A Class D fire is nothing to play with. My fire fighting training from the US Navy sure came in handy when one of my student's set a crucible full of aluminum on fire.

Is this a "one off" or do you have several pieces to machine? If the latter, I seriously recommend looking into sending it out to someone with a water jet. Work hardening, fire, and any other associated issues are eliminated.

tdmidget
06-11-2010, 01:31 PM
hitnmiss it is not harsh. The OP asked a serious question and deserved serious replies. He already knew it could be cut with High speed steel so that covered the hacksaw.
The fire hazard that the chicken littles carry on about is minimal. I worked two years in a shop that was almost exclusively Ti work and never a hint of fire. One poster tells him to have a class D extinguisher as though they were an everyday item. A class D rated for 3 lbs of metal costs about $250.00. The same poster then talks of aluminum on fire. Aluminum does not burn in the molten state.
Further this is being done in his employer's shop. He is trying to save his job. If a temporary employee starts demanding expensive items needlessly he might as well roll his box to the door and forget about it.
I daresay that I am the only poster so far with any experience in Titanium. The OP seems to me capable of sorting what's helpful and what's harsh.

RKW
06-11-2010, 01:36 PM
I agree.

"I would try this or that or maybe" ... does not help since the work is obviously going to happen and not just a consideration.



hitnmiss it is not harsh. The OP asked a serious question and deserved serious replies. He already knew it could be cut with High speed steel so that covered the hacksaw.
The fire hazard that the chicken littles carry on about is minimal. I worked two years in a shop that was almost exclusively Ti work and never a hint of fire. One poster tells him to have a class D extinguisher as though they were an everyday item. A class D rated for 3 lbs of metal costs about $250.00. The same poster then talks of aluminum on fire. Aluminum does not burn in the molten state.
Further this is being done in his employer's shop. He is trying to save his job. If a temporary employee starts demanding expensive items needlessly he might as well roll his box to the door and forget about it.
I daresay that I am the only poster so far with any experience in Titanium. The OP seems to me capable of sorting what's helpful and what's harsh.

hitnmiss
06-11-2010, 01:55 PM
Well then we can disagree. It's a public forum and I enjoy all levels of answers, and still maintain more people than the OP get data from posts. Maybe 3 years from now someone will search this subject and learn something posted that wasn't answering the OP's original question. To chastise someone for posting about plywood discourages people from posting because they are not "expert" enough. I will judge if the answer is expert enough, I don't need others doing so.

macona
06-11-2010, 02:48 PM
I have very limited experience with some titanium, it turns well and will single point thread well, but drilling and taping can quickly become a nightmare. Use a very sharp drill if drilling.


I have drilled and tapped deep holes to 2-56 no problem. I did us a thread form tap though.

Like others have said it is difficult to get the stuff burning and tends to go out easy on small stuff.

Dr Stan
06-11-2010, 03:30 PM
Aluminum does not burn in the molten state.

Trust me, it sure does when it is taken past the flash point. I'm glad I knew how to contain (not extinguish) the fire.

MotorradMike
06-11-2010, 04:40 PM
Aw shucks


http://cache2.allpostersimages.com/LRG/7/789/8XEI000Z.jpg

Are you boys fightin' ova me?

rohart
06-11-2010, 08:24 PM
I've turned some 1 1/2 inch Ti rod using a single point home ground HSS tool in a small lathe, with the associated small feed and DOC.

I had no problems at all, and produced a good finish. Period.

I don't know precisely what it was, but it's unlikely it was alloyed because I measured and weighed a bit of it and it came to exactly the right density.

huntinguy
06-11-2010, 09:24 PM
Trust me, it sure does when it is taken past the flash point. I'm glad I knew how to contain (not extinguish) the fire.

http://www.nbcconnecticut.com/news/local-beat/DEP-Hazmat-Called-To-Aluminum-Fire-In-West-Hartford-90528364.html

Glad aluminum doesn't burn.

As with Ti. There are several different alloys and conditions.

Some of the stuff is a cake walk and some is a pure nightmare. I have machined the stuff and had speeds and feed dialed in perfect and hit an impurity and blew the tool.

I have always held for a starting point: low speeds, heavy feeds, no dwelling for any reason, never go into a corner - always drive it. Some of the Ti I have cut only has an 25 foot band (carbide tooling), 30 down or 30 up from the sweet spot and you will have the fight of your life.

I have been in a shop where there was a Ti fire... trust me, the fire extinguishers don't work too well. If it is a cost thing then get a bucket of talc, that is what the fire extinguishers are any way.

Done being cranky now. :D

tdmidget
06-12-2010, 12:07 AM
Let's lay this Aluminum fire to rest.
Dr. Stan;
Al does not have a flash point
http://www.nttworldwide.com/tech2212.htm
huntinguy;
According to their website, the Abbott Ball Company manufactures balls from a variety of metals, including aluminum, for uses ranging from heavy equipment and automotive to body jewelry.
There is absolutely NO evidence that this was Aluminum. If you believe everything you read in a newspaper you are pathetic.

squirrel
06-12-2010, 12:42 AM
Let's lay this Aluminum fire to rest.
Dr. Stan;
Al does not have a flash point
http://www.nttworldwide.com/tech2212.htm
huntinguy;
According to their website, the Abbott Ball Company manufactures balls from a variety of metals, including aluminum, for uses ranging from heavy equipment and automotive to body jewelry.
There is absolutely NO evidence that this was Aluminum. If you believe everything you read in a newspaper you are pathetic.
tdmidget

aluminum burns at 6920F, it is a component of solid rocket engines and certain explosives.

By the way you are not the only person that "knows" what titanium is and what it can do. I was in the medical industry for a long time and analyzed the grain structures, hydrogen content, chemical composition and other issues with titanium for many years. You can light small pieces of CP Ti with a cigarette lighter and it will not extinguish.

I think you owe a couple of guys on here an apology.

tdmidget
06-12-2010, 01:31 AM
Squirrel; rethink that. Maybe you owe me one. The temperature in a rocket engine is a specific chemical reaction, only possible with a stoichometric mixture of a very fine Al powder and a very active oxydizer. Your argument is tantamount to saying charcoal is dangerous because it is a component of black powder.
Any pieces of Ti that you could light and sustain fire would be on the order of .001" or less unless you have a source of heat well beyond a cigarette lighter and a ready supply of oxygen.
I am well aware of the fire hazards. I was a field instructor for the Georgia Fire Academy. I am a journeyman machinist and millwright. Even if every chip he produced from this operation caught fire at once, it would be over before a fire department could respond. It is a non issue.
If you take the troublee to read the OP you will find that he was aware that Ti can burn and did not need 6 chicken littles to lecture him.
Maybe there are 2 differences here
1. I have extensive experience machining Ti as opposed to analyzing it.
2. I saw that the Op was not a dummy and well on track to success.

Dr Stan
06-12-2010, 12:41 PM
tdmidget

aluminum burns at 6920F, it is a component of solid rocket engines and certain explosives.

By the way you are not the only person that "knows" what titanium is and what it can do. I was in the medical industry for a long time and analyzed the grain structures, hydrogen content, chemical composition and other issues with titanium for many years. You can light small pieces of CP Ti with a cigarette lighter and it will not extinguish.

I think you owe a couple of guys on here an apology.

Squirrel,

Thanks, but do not hold your breath. I doubt if tdmidget will ever admit to being incorrect about anything. I'm just glad my Naval fire fighting training gave me the experience to draw on to safely contain the burning aluminum and there were no injuries. The only causality was a crucible that was easy to replace. It was quite an attention getter when I saw the smoke and sparks coming out of the foundry furnace.

Stan

squirrel
06-12-2010, 10:27 PM
Squirrel,

Thanks, but do not hold your breath. I doubt if tdmidget will ever admit to being incorrect about anything. I'm just glad my Naval fire fighting training gave me the experience to draw on to safely contain the burning aluminum and there were no injuries. The only causality was a crucible that was easy to replace. It was quite an attention getter when I saw the smoke and sparks coming out of the foundry furnace.

Stan
Stan, thats what happens on forums. This is still the better site of all, CNCzone is pretty decent too, the PM site is full of................................
I usually don't reply to the ones like that, it was in the gray area, learned my lesson with that one.

Dr Stan
06-13-2010, 12:40 PM
Stan, thats what happens on forums. This is still the better site of all, CNCzone is pretty decent too, the PM site is full of................................
I usually don't reply to the ones like that, it was in the gray area, learned my lesson with that one.

Squirrel,

Amen to that, especially about the PM.

It did get me to thinking about the aluminum fire. I do wonder if there may have been some magnesium or aluminum/magnesium alloy accidentally added to the melt. That could have served as an igniter for the aluminum.

We bought scrap aluminum to use in the class, so there was no way I could tell what was going into the crucible.

Stan