Author Topic: Working with Titanium  (Read 101811 times)

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Offline Jack Gifford

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Re: Working with Titanium
« Reply #30 on: October 18, 2015, 12:49:31 AM »
I'm curious (and maybe this was answered and I missed it?)- can thread-forming taps and dies be used with titanium? A local aerospace machine shop has switched almost totally over to thread-forming (as opposed to thread-cutting) of tool steels and chrome-moly alloys. Personally, I've never tried them.
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Offline wobblywalrus

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Re: Working with Titanium
« Reply #31 on: October 18, 2015, 08:56:02 PM »
Thread forming makes a stronger fastener.  It is the best method. 

Offline manta22

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Re: Working with Titanium
« Reply #32 on: October 18, 2015, 09:29:55 PM »
jack;

I agree with WW- roll-forming produces a grain structure that follows the thread profile rather than cutting through it. Roll-forming takes a lot of torque, though, to roll the threads on. Since the forming causes the tip of the thread to rise as the root is formed, you have to start with a smaller diameter material.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Jack Gifford

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Re: Working with Titanium
« Reply #33 on: October 19, 2015, 02:28:35 AM »
I agree about the advantages of thread-forming; but I don't know whether it can be employed with titanium? :?
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Offline rouse

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Re: Working with Titanium
« Reply #34 on: October 19, 2015, 10:09:44 AM »
Yes you can thread form Ti. But, careful consideration needs to be paid to a whole host of factors that may come into play.

Ti has very different properties than other materials like Aluminum or Stainless Steel. For that reason, for short runs or one off threading, most folks just cut threads as opposed to thread forming. If you are going to thread form Ti for the first time, do yourself a big favor and start with test pieces in order to perfect the process on your part.

Rouse
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Offline wobblywalrus

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Re: Working with Titanium
« Reply #35 on: December 14, 2015, 01:29:13 AM »
High speed steel tool bits seem to work OK with 6AL4V titanium alloy.  Bits with carbide cutting edges fused to steel give mixed and mostly poor results.  The ti erodes them quickly.  The setup I use most of the time is this washer supporting a tool bit holder.  The holder positions the bit level with the bit tip at the level of the part's axis of rotation.  In bird's eye view the bit is at 90 degrees to axis of rotation.  Exceptions are mad like this where I am cutting at an angle.  The bits are carbide with a geometry and coating to be suitable for all sorts of metals without coolant. 

The total tooling investment for the carbide bits was real reasonable.  It is shown, and it is a box of bit holders with bits and a boring bar, some holders that position the bits level, a parting blade, and a few bits for it.  The different tool holders hold the bits in varying orientations to the part and the bits can be shifted around so all for corners get used.  It takes awhile to completely wear out a bit.

A lot of this stuff was shown in earlier posts on this thread.  Not many folks know how little it costs to adopt this carbide bit technology.  Most of the items shown are hidden deep in obscure catalogs and learning what low budget tools are available is the hardest part.   

Offline wobblywalrus

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Re: Working with Titanium
« Reply #36 on: December 28, 2015, 12:18:15 AM »
Concerns about me taking a perfectly good carbon steel bolt off my bike and installing a titanium bolt I made are valid.  Does anyone have a good reference for titanium fastener design?  It is easy to figure out the clamping force provided by the carbon steel bolt.  Now I need to check the titanium bolt I made and to verify it provides equal or greater clamping force.  Also, I want to design titanium fasteners.  Everything I have is for carbon or stainless steel and it does not apply to ti.

Offline fordboy628

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Re: Working with Titanium
« Reply #37 on: December 28, 2015, 04:45:21 AM »
Bo,

I seem to recall some very basic information buried deep somewhere on the ARP website.   You might also try the websites of the Ti material suppliers or check the Government's aerospace suppliers.    Some manufacturers are going to consider what you are looking for proprietary/trade secret info.

 :cheers:
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Offline rouse

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Re: Working with Titanium
« Reply #38 on: December 28, 2015, 11:11:17 AM »
Shouldn't be any secret about the strength of the materials. High strength CS bolts are going to have better clamping capacity than TI, they just weigh more.

Rouse 
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Offline manta22

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Re: Working with Titanium
« Reply #39 on: December 28, 2015, 12:04:25 PM »
WW;

This has some useful info and it also references other documents that may be of interest.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline wobblywalrus

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Re: Working with Titanium
« Reply #40 on: December 29, 2015, 01:35:33 PM »
Thanks for all of the advice.  My son, Johann, who works at the nuke plant, told me what they do.  Three factors influenced my decision which pertains to clamping force.  This is critical in this application.  The frame is held together with bolts.

1)  I have good data about the grade 10.9 carbon steel bolts that originally came in the bike.  I do not know the grade of the stainless steel fasteners I am replacing them with.

2)  The data I have on the carbon steel bolts and nuts indicates they should be used only once in critical applications.  The ones I am using are 12 years old and have been reused a bunch of times.

3)  The carbon steel bolts are reasonably priced.

The decision is to install all new carbon steel bolts and nuts in the critical locations on the frame and forks.

  I do not have much data about the have a lot of daThey are OEM fasteners, stainless steel bolts I am  and this bike will be moving well above the operational envelope it was pey need to provide adequate 

Offline Polyhead

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Re: Working with Titanium
« Reply #41 on: January 12, 2016, 10:13:15 PM »
I had similar self ignition issues when machining zirconium years ago, (making nozzles for an acid spray cleaner which needed the high corrosion resistance of the zirconium), but I was unaware that Ti could do the same thing, and even in a pure nitrogen atmosphere. 
Gets interesting when your mill catches fire and the spray mist accelerates the fire in the chips because zirconium strips the water just like magnesium does.

The black sand was probably magnetite (black iron oxide).


Aluminum dust will ignite pretty damn good too.  Ask the poor sap that was welding on the dust collection system at one of the local foundaries here in Portland.  There was a loud woosh noise, and a slight pressure wave we felt in the shop.  Then a guy walking around screaming with the skin falling off his arms.  Then the sprinkler system going off in the building.  Rough day at the shop that one.  Anyway, Don't keep piles of either of those metals in dust form inside your shop.  All it would take is one little piece of welding slag to land inside of it and boom, now you got yourself one hell of a fire.
Ben 'Polyhead' Smith
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Offline wobblywalrus

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Re: Working with Titanium
« Reply #42 on: January 19, 2016, 10:41:41 PM »
Titanium is expensive to machine.  It is hard to make fast or deep cuts, it eats up tooling, and the cutting tools are often expensive and specialized.  It pays to plan out the part so it can be made with as little machine work as possible.  This often requires the  purchase of a small bit of ti that is close to the right size.  One source is www.titaniumjoe.com in Ontario, Canada.  They have little pieces and they list the alloys.  The picture shows a little bar I got to make a pair of footpegs.   

Offline Polyhead

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Re: Working with Titanium
« Reply #43 on: January 23, 2016, 11:45:46 PM »
Shouldn't be any secret about the strength of the materials. High strength CS bolts are going to have better clamping capacity than TI, they just weigh more.

Rouse 

Ti may well have longer fatigue life than carbon steel fastners however.

The real thing I would worry about with Ti fastners is corrosion.  Titanium and vanadium don't get along very well.  Vanadium steel tools can cause titanium fastners to start to corrode.  The air force learned this the hard way the first go around.
Ben 'Polyhead' Smith
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Offline rouse

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Re: Working with Titanium
« Reply #44 on: February 24, 2016, 07:21:39 PM »
Shouldn't be any secret about the strength of the materials. High strength CS bolts are going to have better clamping capacity than TI, they just weigh more.

Rouse 

Ti may well have longer fatigue life than carbon steel fastners however.

The real thing I would worry about with Ti fastners is corrosion.  Titanium and vanadium don't get along very well.  Vanadium steel tools can cause titanium fastners to start to corrode.  The air force learned this the hard way the first go around.


That hasn't been my experience.

Rouse
Johnnie Rouse
Bike 4680 P-PP2000 SCTA record 153.325    A-PF3000 182.920
                              Texas Mile 152.518 PP class  186 A-PF Class
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