View Full Version : Pulser?
07-31-2005, 08:53 PM
Ive read alot about pulsers on tig and mig welders but i dont understand what they actually do. I would appriciate it if someone could explain this to me.
08-01-2005, 01:52 AM
That is a difficult question because it means different things with different manufacturers. The main point to understand is that welding machines that use pulse are inverters and are controlled by integrated circuits. In conventional welding the current is either AC or DC but with the new power supplies the current is anything you want it to be.
You can have a square wave alternating current as opposed to a sine wave. This will allow you to use stick electrodes that are intended to run on DC only. Because the rod is running either electrode negative or electrode positive you are in effect running DC, switching back and forth almost instantly.
Imagine you want more electrode negative or more electrode positive. That is possible by simple adjustments. You can also change the frequency that it changes from once a second to thousands of times a second.
At this point you have changed the current to the point that you have to be a combination electrical engineer and welding engineer to understand what is a useful combination. Lincoln Electric supplies a line of power supplies that can be linked to a laptop and using custom software adjusted any way you want. The software displays a graphic image of the current versus time and you change it. I talked to one Lincoln salesman who told me about one customer who changed so many things they just had to erase everything and install the original default settings again. I notice that for wire feed machines they are often "synergic" You set the wire feed, type of wire, diameter, type of gas and the unit gives you a pulse arc current most suitable. At that point of course you still don't like it so then you adjust your trim which slightly changes the characteristics. On the one I use it is expressed as 1.00 If I don't like that I can dial it up or down to say 0.89
If I want more heat I turn the wire feed up and the computer changes the current. On .045 metal core wire I can adjust from over 350 inches per minute down to 50 inches per minute. At the low setting I was able to tack weld on 1/16 thick expanded metal. With a conventional wire feed power supply such a thing is not possible using .045 hard wire never mind metal core.
02-21-2006, 03:21 PM
I would also like to hear a good explanation of pulsed TIG...
02-21-2006, 04:33 PM
Sorry - off topic - but with no messaging.....
Rubicon - were you on monster garage? Which episode?
02-22-2006, 02:36 AM
Since no one has ventured a description of pulsed TIG/MIG, I'll wade in with an amateur description of the advantages it is claimed to offer.
Basically, pulsed TIG refers to a current control technique that involves switching the welding current between two (or more) current levels at a rapid, programmed rate. Such control is easily achieved in modern, microprocessor-controlled power sources. The welding current for a particular operation might switch between, say, 100 amps and 20 amps several times per second. The claimed advantage is that for certain metals, thicknesses, and orientations, welding at the constant current that gives optimal penetration, wetting out of the weld pool, etc., could result in melt-through or dripping out of the pool. The low current periods between pulses are claimed to allow some solidification of the weld pool so that melt-through or dripping out can be controlled while still achieving good penetration, wetting out, and weld pool control. I, personally, have never used pulsed technology and have no opinion of its virtues.
There is a prominent welding engineer/consultant, Ed Craig, who says that pulsed TIG/MIG is a crock and that the claimed advantages can be achieved better and more cheaply by proper setup and adjustment of weld parameters using conventional, high quality equipment. Check out his website, rather than relying on my poor paraphrase of his position(http://www.weldreality.com/default2.htm).
I hope the discussion doesn't stop here with my very minimal understanding of pulsed TIG/MIG. It would be helpful to hear the opinions and experience of an experienced user of pulsed technology.
02-22-2006, 04:15 PM
As AWRIGHT says, the primary advantage of Tig or Mig pulsing is in getting good fusion, while fighting gravity, when making "out-of-position" welds (vertical, overhead, horizontal).
Low frequency pulsing (1 to 20 pulses per second) of Tig can produce a weld essentially composed of overlapping spot welds (nice rippled appearance).
High frequency pulsing (300 or so pps) in Mig can allow out of position (pulsed) spray transfer, with much better fusion and less spatter than short arc.
Low frequency pulsing can also be superimposed on top of the high frequency pulsed Mig, called "Pulse on Pulse" by Lincoln, this can produce the overlapping spot weld effect like a Tig weld.
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