What is a good setting of the pulse parameters for tig welding equipment?
Welding near an edge on .125" 308 stainless steel
30% on time
Weld build up on the edge of .050" steel, stainless, or nickel alloy
20 % on time
20 percent background
Build up of threads on a 1 inch thick 4340 shaft
50 % on time
50 % background
There are other settings that would have worked too but I thought I might just list a few so that you would have some good places to start on certain jobs.
Every tig welding machine is slightly different but the concepts are basically the same. There are 4 basic settings to understand:
1. Main Amperage - if you are using a foot pedal, you will vary the main amperage but remember this tip...You will need to set the main amperage at roughly twice the amperage you would select without pulse because with pulse, you get an average of the high and the low...roughly.
2. pulse frequency in pulses per second or pps - I like to either weld at about 1 pps, or above 20....preferable above 30.
3. Pulse Time on in % also known as pulse width - This is the percentage of time the current stays on the high side of the pulse. For starters, I recommend 30-50 percent...if you go much lower than 30, it just limits your heat too much and you wind up just giving it more foot pedal to compensate.
4. background current - Background current is the low current of the pulse. This is not the percentage of time but a percentage of the high pulse amperage. On some machines it is just the exact background amperage but either way, The lower you set it, the more pulse effect...to an extent. Just like the pulse time on, if you go too low with this setting, it just limits the output of the machine too much...I recommend setting it at 20-50 for starters.
Older transformer style welders can only manage a maximum of about 10-20 pulses per second. If you have ever had to weld at 10 pps, you know what I know. It sucks.
I would rather get kicked in the stones than to have to weld all day at 10 pps.
But some newer inverter tig inverters are capable of 500pps and higher.
Where do you need 500 pulses per second? You probably dont .
High pulse rates like 500 sing at a high pitch and make you want some earplugs. The arc stiffens but as far as controlling heat, it does not offer much benefit.
But pulse rates of around 100-150 have a really nice effect on the arc. The arc is stiffened just enough to want to stay where you put it, more focused, and wanders less ...it sticks where you put it and when you are welding next to an edge or corner, it really helps keep the heat from wandering to the edge.
In fact any pulse rate between 33 and 150 helps make the puddle stay put,,, in my opinion.
Here are some things I have observed about pulse.... pulse rates of 30-40 agitate the puddle and let you move the puddle at a slightly lower average amperage than without pulse....
Pulse rates of from 50-150 really stiffen the arc and let you pinpoint the arc more than without pulse.
Pulse rates of around 0.7pps to 2 pps limit heat input the most and prevent heat buildup in the part being welded.
and one more thing...pulse tig really shines on automated welding applications much more so than manual welding with a foot pedal.
Travel speed and amperage adjusted by the welder will often negate a lot of the benefits of pulse tig welding equipment.
• Dont fart around...start the arc, create the puddle, get to welding, get out.
• Use as small a tungsten as practical and keep it sharp and clean.
• Set your tig welding equipment to the lowest amperage that is practical. I am not talking about using such a low amperage that the weld takes forever to get a puddle…just use enough to where you can get the puddle going within a second or two and then get moving, but dont use more than is needed .
• Use the smallest filler rod that is practical. If dipping the rod in the puddle seems to suck all the heat out of the puddle, use a smaller rod.
• If distortion is your main problem, Weld in short stitches wherever possible.
• Back-purge your stainless welds with argon…if you don’t, pulsing will not have much benefit.
• A good pulse setting For controlling heat input is setting the percent on time and background current to around 20% each.
• Make sure you get a, tight, tight joint fit-up.
• Clamp everything as solid as possible to heavy pieces of aluminum or copper, if possible.