Vertical Pulse MIG
Today we are discussing and demonstrating Pulse Spray MIG in the 3G position. Pulse Spray is an alternative to Spray transfer, which is restricted to flat fillets and grooves and horizontal fillets only.
Spray has many advantages such as, ability to weld thicker materials, less spatter (resulting in less cleanup) and in some cases faster travel speeds. However because it is position restricted, we cant weld in the vertical or overhead position. Many would think that the best thing to do in this case is to use the Short Circuit mode of transfer since it is able to weld in all positions. However, Short Circuit is limited in thickness. It is not recommended to weld materials thicker than 5/16" (8mm). Does it happen, of course it does. But it should be avoided at all costs. In cases where thicker material must be welded out of position, we can use Pulse Spray transfer. It is essentially a modified Spray transfer and has sudden pulses of high current and a lower background current that allows some cooling to take effect while welding to make the weld pool more manageable.
A couple of things are needed to run Pulse Spray, the first thing you will need is a machine capable of running pulse. Secondly, you will need a gas composition which contains 82% or higher Argon. I recommend at least an 85/15 to allow for a the fill mixture to be slightly off. I typically run 90/10 myself but that a personal preference.
One of the biggest differences in Short-Circuit and Pulse Spray is the Contact Tip to Work Distance (CTTWD) with Short-Circuit transfer a 3/8" to 1/2" CTTWD is recommended. But once we get into a Spray of Pulse Spray transfer, we need to be around 3/4"-1" for our CTTWD. Too short of a CTTWD will not allow the wire to burn off at the correct point of the wire. You will know if your CTTWD is too short cause you will hear a crackling sound as you are welding. Too far out and the puddle will start crown up due to the loss in amperage.
Now that we have the appropriate machine, gas and CTTWD, let's talk about technique. Pulse Spray is a pretty simple process to run and doesn't require much effort to create a decent weld. In the flat, horizontal and overhead position, we only need to do a slow steady push down the weld joint. Vertical is a little bit trickier but not too difficult. You will just have to manipulate side to side just a tad and watch the weld pool tie in to the parent material. The video above shows in detail how to perform the root, fill passes, and final cap of a typical AWS Complete Joint Penetration (CJP) weld in the vertical position.
If you need any further information regarding Pulse MIG, drop a comment in the section below. We hope you enjoyed the content in the video and in the article. Until next time, Make Every Weld Better Than Your Last.
About Jason Becker
Jason Becker is a welder/fabricator with 22 years of field experience in the welding industry and a Marine Corps Veteran. He is also an AWS Certified Welding Inspector and Certified Welding Educator (CWI/CWE). While teaching welding at his local college, Jason pursued his Bachelors Degree in Construction Management from Seminole State College and graduated with honors in 2016. He now works full-time as the co-host for Weld.com.