When it comes to manual labor, it sounds pretty much easy, and welding is one of them. However, as an operator, you need to have basic knowledge of the process to get the job done properly.
‘Welding current’ – does it sound something familiar? Well, if you ever have had a chance to be in welding class, I’m sure you have heard of this. There are lots of welding machines in the market labeled as AC or DC – alternative current and direct current label tell of the machine’s current.
Now, you might be wondering, ‘what is that thing called polarity in current’?
When the welding machine is turned on, an electrical circuit will be created, and it will have two different poles – one is negative, and the other is positive. And the property here is known as polarity.
Today, we are going to be discussing what polarity for stick welding is needed. Before we jump into the topic, here’s something you need to know.
AC Current and DC Current:
In direct current (DC), the flow of electric charge is only towards a single and specific direction. It has a constant polarity. In alternating current (AC), the flow of electric charge rhythmically reverses its direction. So, the welding machine with a DC label comes with constant polarity, and for the AC label, the polarity changes.
Variation of AC and DC Current in Welding:
DC comes with a lot of advantages, and that’s why in shielded metal arc welding, DC is being used widely. When you weld using DC, you will get a much smoother and solid arc. So, it becomes a lot easier to strike the arc.
Therefore, you won’t have to deal with a lot of spatter and outages. And it’s going to decrease the difficulty in vertical up also overhead welding.
Yeah, it’s true that DC comes with a lot of advantages. However, AC is also used in different cases. For example, AC is widely used in welding training as it doesn’t cost much. Also, in shipbuilding welding, people have been using AC current for a long time.
Different Kinds of Polarity:
In welding, there are three individual types of polarity applied. Let’s get acquainted with those:
Direct Current Straight Polarity:
In direct current straight polarity, the electrode is constructed negative, and plates are the opposite. Because of that, the electrons will pass from the electrode end and then to the base plates.
Direct Current Reverse Polarity:
If the plates are negative and the electrode is constructed positive, that’s when direct current reverse polarity happens. In this process, the electrodes will pass in the reverse direction from the base plate’s end and then to the electrode.
Alternating Current Polarity:
When you are using AC current as a power source in that situation, either one straight and reverse polarity will happen. The base plates will remain positive, while half the cycle will stay negative.
What Polarity is Needed for Stick Welding?
The most common method for stick welding is using DC+ polarity. Because it gives a great bead profile and an elevated level of penetration. On the other hand, you will get less penetration and a bad electrode melt-off when using DC- polarity. In most cases, we see it’s used on narrow sheet metal to stop burn-through.
Advantage of Using DCEP:
DCEP refers to Direct current electrode positive. This process is preferable because it has a good arc cleaning action, so there is no possibility of inclusion defects. And welding is much faster with a high volume disposition.
It greatly lessens distortion, residual stress, and fulfilled cutting; therefore, you will get a good performance when welding thin plates.
The disadvantage of Using DCEP:
DCEP also has some cons; most notably, it has a shorter electrode life when dealing with non-consumable electrodes. If you fail to adjust the speed accordingly, you might have to deal with a high level of reinforcement.
The polarity of Alternating Current:
You will have a good experience with AC polarity as it offers a great advantage for both DCEP and DCEN. It will provide you with moderate cleaning action and is supported by almost all types of electrodes. Also, you will get better fusion and penetration, which is perfect for many types of plate thickness.
Frequently Asked Questions:
What is the most suitable type of stick welder for general use?
It doesn’t matter if it’s an electric powered arc machine or gas engine driven welder, a perfect welder of general use must have AC/DC output. In most cases, you will get better performance from DC welder than AC.You will get fewer spatter, nice looking welds, simple vertical up, and overhead welding. The process is a lot easier to learn and provides a smoother arc. You might be happy to know that you are going to get near about 10 percent better penetration from DC welder than AC.
Does AC output have any benefits?
Yeah, indeed, especially when you are welding a material that can get magnetized from friction. In this case, a DC welder won’t function as a result of arc blow.
Do I need a big machine?
For general purpose welding, a 225-300-amp stick machine will do just fine. It is an ideal choice because it requires only 200 amps or a few. When welding material thicker than 3/6 inch, it just makes several passes, and that’s how a professional works. Try some compact machines like the AHP Alpha 200X to get the best output.
What does this word called ‘duty cycle’ on my spec sheets mean?
It means that how many minutes a welder can run out of a 10-minute cycle. For instance, a welder generates 200-amp DC output at 20 duty percent duty cycle. It is able to weld constantly at 200 amps for two minutes; after that, you have to leave it for a certain time to avoid overheating.
What will happen if I weld with the wrong polarity?
If you use the wrong polarity, it’s going to create spatter, bad penetration, and poor control over your arc.
Is it important to remove rust before welding?
What I can tell you is you are not going to like to weld without removing the rust and oil from it. If you do, it may cause cracking and lack of fusion resulting in bad welding.
So that’s all we had on what polarity for stick welding do we need. Apart from this practical knowledge, it is recommended that you go through a bit of theoretical idea, as well. If you have a good depth of knowledge on how AC and DC flow work, it’s just a matter of seconds to understand how to apply polarity in your projects.