We are frequently asked if there are any real benefits of using pulse over CV in the MIG process. The short answer is “absolutely.” But before we can answer we need to ask: “what is the application?” To really appreciate the benefits of pulsed GMAW compared to traditional CV (short arc or globular) it is helpful to have fundamental knowledge on the different modes of metal transfer.
Pulse welding is simply alternating between a peak (high) and a background (low) current. Metal is transferred through the arc during the peak current. It is also important to mention the difference between pulse and spray pulse. Many people use these terms interchangeably and it can create some confusion. When we say “pulse” we assume “spray pulse”. Spray transfer is achieved when the arc reaches an energy level at which the molten droplets are transferred through the arc. Below this energy level metal is transferred by creating a short with the base material and then separated by a blast of amperage. Pulsing is a feature of the power source. You can be pulsing (alternating between high and low current) but if you are not above the transition current you would not be in a true spray transfer. You would get some benefits of pulse welding, but not all. The advantages and limitations shown below assume you are spray pulse welding. The other variable in achieving spray transfer is the shielding gas. You need to have at least 80% Argon. Common blends suitable for pulse welding are: 90%Argon/10% CO2
Advantages of Pulse Welding
– Reduction in overall heat input (decreases distortion, decreases the heat affected zone)
– Reduction in spatter (reduces rework and secondary operations)
– Higher deposition rates out-of-position (product of rapid cooling of the puddle during background current of the cycle)
– More resistant to lack of fusion than other modes of transfer (most people assume pulse welding reduces penetration)
– Can reduce fume levels generated by the arc compared to other modes of transfer
Limitations of Pulse Welding
– Equipment is typically more expensive than conventional step-down transformer power sources
– Gas blends required are more expensive than the commonly used 100% CO2 or 75%Argon/25% CO2 gas.
– Higher arc energy produces higher levels of radiated heat and a brighter arc, this requires a darker shade for the welding lens and more protection for the welder (usually gloves with heat shield)
Do you have experience with pulse welding? What are your thoughts?
I liked that you said that pulse welding will help reduce excess fumes. I would imagine that fumes would be harmful to your health. I would consider using pulse welding to eliminate harsh fumes.
Pulse can certainly help reduce fume provided the welding parameters are set right. Being in spray mode is essential. You can set a welding machine on pulse but if your amperage and/or voltage is too low you will be in short circuit or globular transfer. Pulse helps because you are able to get into spray at a lower average current. The base material is also a huge contributor. Good luck.
I liked that you mentioned that pulse welding can reduce fume levels generated by the arc compared to other modes. I’ve had some welders who have been uncomfortable with the fumes and its helpful to know that we can reduce that. Maybe I’ll have to try pulse welding and see if that helps our welding services.
Please let us know how that goes. Keep in mind that you still need to be in spray transfer. If you run a pulse waveform but your voltage is too low you will start shorting the wire which will generate more spatter. Good luck.
Can anyone tell me the technical reason why pulse and spray arc is not possible with 100% Co2?
Hello Ketan. To to into spray transfer you need at least 78% or more argon (inert gas) with the balance being CO2. This has to do with the shielding gases ability to create a stable medium through which the molten droplets of metal are transfered. Carbon Dioxide is an active gas and facilitates chemical reactions which affect the arc and the weld. When using CO2 as the shielding gas the cathodic forces push upward from the puddle to the tip of the wire. This creates globules if our amperage and voltage are high enough or shorts (short circuit) if the amperage and voltage are low. Spray and pulsed spray are possible when we reduce the CO2 content to below 20-22% (meaning argo is at least 78% or more). When we do this the amount of CO2 does not exert enough force to cause globular/short arc transfer and allows for axial spray transfer (transfer of molten droplets of metal through the arc).
That is really nice that pulse welding gives a good reduction in spatter. Something that I have been wanting to learn more about is different types of welding. Maybe I should look more into it and see how welding can benefit other people.
after 40 years straight mig on alu, i bought lorch twin pulse
used in single, it is like snailmail, slow beyond belief, i could run with the cv arc just on the spray , so fast building yachts, i still have the miller deltaweld, from 1980, 450 apms no probs, used to run the HOBART LINEAR 2 GUNS these days i have an aluma pro gun and miller xr feeder, simple fast reliable
My employer just switched the entire shop over to pulse welding. Were running .045 wire and they have the parameters set with a low of 40 amps and a hight of 60 with wirespeed low set at 250 and high 395. It’s way to hot for the 1/8 inch thick stuff we’ve been welding. I don’t think he knows what he’s doing but I don’t know enough about pulse to correct him. Anyway I could get the correct parameters for running that wire size on a metal up to 1/4 thick?
Hello Dave. What welding machine are you using? Typically when you run pulse you do not set high and low amperage, the welding machine will do that for you automatically. Sometimes the problem with pulse is that in order to get a true spray transfer the voltage may have to be raised. This is especially true if the reason for going to pulse was to eliminate spatter. If you are doing from short arc to pulsed spray you amperage may be similar but your voltage will be much higher.
Please let us know the welding machine you are using. If it is a Miller Continuum or Axcess or Lincoln Electric Power Wave please let us know the waveform you are using.
no, on i/8 alu, typical fillet single pulse 105 amps, iknow zero of mig in steel, i am a stick man, let me know if you need help alu 045 1.2 mm 5356 alu wire
I am learning how to weld right now and thought before we got further into the course that it would be smart to look at different types of welding. Pulse welding sounds really interesting to me as it has a reduction in the overall heat input! It is really cool how because of that, it can decrease the distortion! Welding is something that I am enjoying learning about!
Hi Dave. Thanks for your comments. Good luck in your journey to learning more about welding. Be sure to let us know if you have any questions or if we can help you in any way.
Wow, I never knew that pulse welding has the advantage of reducing overall heat input and spatter. My younger brother is looking at welding as a career and I had never learned much about the craft, so I want to learn more and support him. Thank you for the information about how these reductions can help with keeping you from needing to rework a piece and do secondary operations.
Hi, i was being told that with pulse mig + solid wire (normal mig wire) the penetration and tensile result of it manage to achieve same like flux core welding, is it true?
Hello Alan. What determines the tensile strength of a weld is a combination of the base material and filler metal tensile strength. If you use as 70,000psi wire, such as an ER70S-6 or a 70,000 psi flux-cored wire, such as an E71T-1, the resulting tensile strength should be the same. Keep in mind that the tensile strength for the filler metals are minimums. An ER70S-6 wire may actually make a weld with a tensile strength of 80,000 psi or more.
To answer your question, pulse mig does not (by itself) increase tensile strength.
Penetration is affected by the amperage. Flux-cored wires have a hollow core and the current is only conducted through the sheath. At the same amperage an .045 flux-cored wire should penetrate more than an .045 solid wire. Of course, penetration can be affected by many other variables. Read: 7 Variables That Affect Penetration by clicking the following link:
https://weldinganswers.com/7-variables-that-affect-weld-penetration/
It makes sense that pulse welding would limit the amount of heat dispensed at one time. Having this as an option for welding machines would probably be good because it would limit the amount of energy you would need as well. That way you save money on the welding that you have to do in order to produce everything.
Being able to reduce the amount of fumes produced when welding would be important if they were potentially harmful. I have no experience with this kind of thing though so I would probably just hire a welding service for anything that I might need. It would probably be cheaper that way than trying to learn how to weld then buying all the equipment that I would need.
Hi Kylie, you are right. If welding is not a core operation in your business hiring a contractor or welding service is probably the best thing. Welding fumes can be harmful. The degree to which they can affect welders depends on the contents of the fume (particulate) as well as the concentration. Per good practices we should always try to minimize our exposure to welding fumes, regardless of whether they are harmful or not.
I knew nothing about pulse welding by reading this article. I like how you explained that pulse welding can help to reduce fume levels. I hope that I can remember this article the next time I have to have something welded.
I am wanting to learn more about welding. I like how you mention pulse welding can reduce fume levels. I would imagine this would be beneficial to lessen the fume levels for the welders health. Thanks for the information!
Thanks for your comment Alise. Really enjoyed reading your company’s blog posts on stainless steel and aluminum. We sometimes get to focused on how to weld materials we forget about all the benefits it provides the end user on a finished product.
I worked as an inspector at a fabricator that used Pulsed Arc for fabrication of 317LMN scrubbers and ductwork. One thing I must say is that just like short circuit, improper settings can result in lack of fusion. Though it is pulsing and at some point hitting the transition current, the welders can easily adjust “TRIM” to a point where the arc is long, or WFS where the overall heat input is too low.
I think we all could use some specific training on what we are doing sometimes. Often time MFg’s get some equipment on suggestions from someone but really never study the process. I don’t know all I should know about it.
You are correct. As welding technology advances there are more and more variables we can control. New machines have the ability to lock out welding procedures (amps, volts, CV, pulse, etc) but unless you are welding with a robot you will always have the human variable.
What we have found in our experience is that training welders is essential, regardless of how long they have been welding.