Welding Tips and Tricks

Attempting to learn to weld titanium with 1990s vintage Syncrowave 351 and pulse control PC-300. Am confused about settings.

Can someone possibly give me some insight on the proper settings for welding .040 thickness 1” titanium tubing?

My other settings are DCEN, HF start, 35cfh with 16 Pyrex cup with 1/16” 2% thoriated tungsten, .045 titanium rod. 19 second post flow.

I was told to set it up at 40% max amperage of 180 amps, 10% background, 35% on time and 7 pulses per second.

I’m having trouble getting a good bead profile and some trouble starting the arc.

The only pulse info I can find these days are for the built in pulsers in the new inverter machines ( which I haven’t used yet ) rule of 33 etc. How different are things with these old 60 hertz transformer machines?

I guess my questions are - I thought the 1 amp per 1/1000 rule applies to all metals - 180 amps seems high for .040 wall thickness - even if set at 40% max via pulse; everything I’ve read about titanium indicates low amps because heat can make the weld brittle. why do you set it at 40% of max amps versus 100% when pulsing.

Look forward to any tips on this. I have more questions on titanium but first I need to make sure I’m understanding how to work with the pulse control.  

D

The 1 amp per .001" rule is just a starting point, and really only for plain steel, IMO. Aluminum will need more amps, and stainless will need less amps, both due to their thermal conductivity. Aluminum conducts and dissipates heat very quickly so more heat (higher amps) is required to maintain heat at the weld puddle since so much of the heat is being pulled away from the weld area very quickly. The opposite is true for stainless since it is a relatively poor thermal conductor and dissipates heat within itself very slowly. This causes the heat to build up at the weld area, and this typically leads to the weld needing less amperage than steel or aluminum of the same thickness.

Titanium has lower thermal conductivity than even stainless, so even more heat buildup at the weld puddle. I don't weld much titanium, so I'll defer to others on best practices there, but you should expect to be well below the 1 amp per .001" rule when welding titanium...even more so than when welding stainless.

The "40%" for pulse is referring to a background current. This means that when you are pulsing, the amperage is cycling between 100% amperage (the welding current based on your switch settings or the position of your foot pedal), and then 40% of that welding current which becomes your pulse or background current. The way manufacturers use the pulse terminology here varies quite a bit, and that can be annoying. So basically you will be cycling between 100% amperage and 40% amperage when you are "pulsing at 40%" if that makes sense. The other factor here (other than frequency) is pulse "time on" which dictates how long of the pulse cycle is dedicated to that 40% background current. Again, unfortunately manufacturers vary on how they use this terminology so "pulse time on" can sometimes refer to the 100% side and can sometimes refer to the 40% side in your example (the background current).

Hope that helps. And bring your amperage way down from the 180A for titanium even when pulsing. You generally need more amps when pulsing, but no where near that much more for .040" material. Try pulsing with 40-60A and dial it in from there.

I practiced titanium for fun using some parts Zank sent me a few years back. Definitely needs very little amperage like Spartan said. Filler rod should ideally be 0.035" diameter or 0.030". Heat sinking is your best friend against excessive oxidation. I used 1/2" wide tinned copper braid wrapped around the tube to wick the heat out, and it worked great! If I got my Ti scrap to practice, I would be trying 80A on the machine, 25% background on the low part, 35% duty cycle (on-time), 0.8 PPS. Of course I would be using the foot pedal to modulate the actual amperage that I would need.

(I don't know why the pics are coming out multiple times, I only inserted the links once. Forum is screwy).

Everyone has their own way to tig titanium that works for them. This is my way:

Firstly internal purging is a must.
My settings for 3/32" 2% lanth tungsten and 1/16" filler wire:
peak current, 48amps
On time, 50%
background current, 50%
PPS, 2.5

Adjust with peddle as you go. Watch for the tiny fish eye at the leading edge of the weld pool, that way you know you are penetrating fully.

Hey thanks for the info! This helps me understand the pulsing etc much better. The copper braid heat sink is a great idea.

Will put this info to good use!

Thanks again !

D.