Changing welding polarity
On most jobsites, changing polarity is a common occurrence — sometimes many times a day for every welder. One example is when operators need to switch from self-shielded flux-cored welding to gouging.
But when making a polarity change requires walking back to the power source to swap cables, this wastes a lot of operator time. The added downtime can be a problem when operations are trying to meet construction deadlines or optimize their skilled welders’ time.
Learn more about welding polarity and how technology can potentially save hours per day by making it quick and easy to switch polarity at the weld.
The basics
An electrical circuit is formed when the output of a welding power source is turned on. The circuit has either a positive or negative pole, and this property is referred to as polarity. Polarity directly impacts the quality and strength of the weld. There are two types of polarity: direct current electrode negative (DCEN, which is also called straight polarity) and direct current electrode positive (DCEP, which is also called reverse polarity). The difference between these two is the direction of the current flowing through the welding circuit, depending on whether the electrode lead and work lead are connected to the negative terminal or the positive terminal.
Welding processes run in either DCEN or DCEP. Stick welding and gouging are usually DCEP, while self-shielded flux-cored and TIG welding are typically DCEN. The polarity necessary for the process can sometimes depend on the electrode or filler metal being used.
Trying to weld or gouge in the wrong polarity can have different effects in different processes, but all would result in poor welding or gouging performance. For example, in the case of TIG welding in the wrong polarity, the tungsten would melt because all the heat is in the tungsten and not in the workpiece.
Changing polarity on the jobsite
On construction jobsites, operators often need to switch between processes for different steps of a weld. A common example is going from self-shielded flux-cored welding to gouging and then back again. Another example is when an operator uses different wires depending on the welding position. When welding in the flat position, a T6 wire is often used, which requires electrode positive polarity. But if the operator switches to out-of-position welding, a T8 wire is typically used and therefore the operator would need to change to electrode negative.
Most power sources require swapping a cable to make the switch from one polarity to the other. This means operators must either leave the spot where they are welding to walk to the power source and swap the cable themselves, or they must radio for a helper to do it. In the cases where a helper makes the switch, they may be guessing which cable and machine is the right one for that operator if the machines or cables aren’t labeled properly.
Both of these options are inefficient and waste time when polarity must be changed. In addition, when operators must walk to the power source multiple times across a crowded jobsite to change polarity, it increases safety risks and the potential for slip, trip and fall injuries.
A better solution
Technology on welding systems from Miller removes the hassle and guesswork from switching polarity. This improves jobsite safety and saves time so operators can spend more time under the hood with fewer distractions.
XMT® 650 ArcReach® Systems and XMT 350 FieldPro™ systems are both available with polarity reversing models. With these systems, operators can switch polarity and switch between welding and gouging easily from where they are working — eliminating the need to walk to the power source and swap cables.
The operator simply pushes a button on the front panel of the wire feeder or stick/TIG remote to choose the process they want to use. The system automatically chooses the correct polarity — either DCEN or DCEP — for that process setting. The polarity change is made internally within the power source, so there is no need for operators or helpers to connect or disconnect cables.
To take advantage of this time-saving technology, both the welding power source and the wire feeder or stick/TIG remote need to have ArcReach technology, which is what makes the automatic polarity switching possible.
Benefits of easy polarity switching
When operators can change processes and polarity right at the feeder or remote — including switching between welding and gouging with the push of a button — it delivers many benefits for the welding operation.
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Time savings: An obvious benefit is the time that can be saved when operators can push a button to change process and polarity, rather than walking across the large jobsite to make this switch at the power source. They also don’t have to swap the leads, another time-saver. The time savings can be especially significant on large weldments that require frequent switching between processes. The bottom line: when welders stay at the weld joint, more work gets done.
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Improved safety: Eliminating the need to walk to the power source to switch polarity means less risk of injury due to slips, trips or falls — leading causes of injuries on construction jobsites. In addition, workers no longer have to handle hot cables in order to switch polarity, reducing another potential safety hazard.
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Better weld quality: When the system ensures operators are in the proper polarity for the process, this reduces rework and scrap. Even when operators or helpers are unsure of the correct polarity for the process, the machine will automatically choose the right one.
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Cost savings: Eliminating the need to swap cables every time polarity is changed helps extend cable life, since they are being connected and disconnected less, reducing wear at the connection points.
Save time and improve safety
ArcReach capabilities eliminate the time spent swapping leads to switch between welding processes that use different polarities. These changes can now be made with the push of a button, saving operator time and reducing safety hazards on the jobsite.