Knowing a variety of welding techniques will help you become a better welder, and ultimately pick up more jobs. One of the most commonly misunderstood techniques is called pulse welding, which I’ll cover in detail in this article.
What is pulse welding? Pulse welding is welding that alternates between a high and low current. This reduces the overall heat input and spatter while ensuring greater resistance to a lack of fusion. The benefit of this is that you can weld both high heat conductive and thinner metals without burning them. Additionally, you can accomplish narrower and more penetrating welds on thicker metals with this type of welding.
What is pulse welding? A deeper look
A variant of the traditional welding process, pulse welding is a form of welding in which the current is pulsed. We explained in the very beginning what this means. However, we will now dig deeper into the pulse welding process to find out everything it entails.
To understand pulse welding, let’s compare it with TIG welding which is one of the most commonly used welding processes today. In TIG welding, the amperage on the welder is set to the desired max level by the user and the foot pedal is used to control its output.
Generally, the pedal throttle is kept constant during the TIG weld and only minor adjustments are made to add more heat or lower it exceeds reasonable levels. The TIG torch’s output is reflected directly by the distance to which the pedal is pressed down.
On the other hand, users operate the food petal in pulse welding just like they do in TIG welding; the only difference is that the TIG torch produces the output in a pulse wave form instead of a stable amperage. However, just like in TIG welding, you can use the pedal in pulse welding to make adjustments to add or lower heat if needed.
Now that you have a basic understanding of pulse welding, it is time to dig deeper into everything involved in the process. Following are some common terms associated with pulse welding and what they mean:
What is pulse frequency?
This is the frequency with which the welding amperage goes from peak amperage to a basic current in a second. This will depend on how high you set the amperage on the welder. For example, if you set it at 50, then it will pulse from high to low fifty times in a second. If you set it to 1, then it will pulse only once every second.
While you can set it at any level you like, it is recommended that set the pulse lower than 4 or higher than 30. This is because the strobe effect of frequencies between 4 and 30 can cause a lot of discomforts. However, you should find your own tolerance levels and stick to them.
The reason why lower frequencies such as once per second or less are recommended is that feeding the filler rod in accordance with the pulse is easier at such levels. With this, a more uniform ascetic weld is achieved. The rule of the thumb for increased metal thickness is higher pulse settings per second.
For thinner metals, low pulse settings are the way to go. For example, fifty pulses or less per second for 3mm steel and a hundred pulses per second for 12mm steel are recommended as suitable pulses. However, there are many differing opinions about the ideal pulse frequency. In other words, the ideal pulse frequencies are subjective and vary from person to person.
What is pulse duty?
In pulse mode, the pulse duty is what balances the time at the peak current level and the low current. The equal time at high and low is 50%. This is because the TIG welders that do allow users to control this setting typically come with a fixed setting of 50% pulse duty.
What is slope down?
After the trigger of the torch is release, the slope down sets the downtime of the power slope. What does this time refer to? It refers to the time needed to minimize power from the existing welding current to zero. This helps to prevent burns and is useful for welds that abort at the material’s edge.
What is gas pre-flow and post flow?
This applies to both pulse welding and other variants of the welding process. Before you strike an arc, you can set the gas to start flowing. This will allow you to purge the welding area. Additionally, it will ensure a good starting weld by purging the weld’s starting area.
Even after you stop welding, the post flow setting will allow the flow of gas to continue. This, in turn, allows the weld to condense in appropriate atmospheric conditions. However, after you release the trigger and the welding stops, you are required to hold the welding torch over the weld till the time the gas stops to flow.
These are some of the common terms associated with pulse welding. Therefore, by understanding these terms, you can get a good clue of what is pulse welding.
Why use pulse welding?
This is one of the most frequently asked questions about pulse welding. There are several reasons to use pulse welding. First and foremost, pulse welding can help achieve the same weld penetration as the other variants of welding with less heat and power. Not only does this save energy, but it also prevents the material from getting warped due to the welding process.
In addition to the above, the working duty cycle ratings of welders is based on the relationship between the amperage used versus the required waiting time for the welder to cool off and be available for reuse. The amount of a time a welding machine needs to cool off will depend on how much power is needed by it. The less power needed, the lower the time for the machine to cool off.
Another reason to use pulse welding is that it makes easier for you to create a reliable and more uniform weld. Finally, a weld produced by pulse welding is visually appealing and looks like a perfect weld produced by a machine. All these reasons should encourage anyone to consider pulse welding for their weld.
When should pulse welding be used?
The condensing activity of the weld is aided by pulse welding in out of position welding; this occurs while the molten metal is being prevented from splashing out of the joint by the background cycle. Therefore, in times where there is a high risk of burn, pulse welding is recommended for welding thin metals.
To give a pleasing effect and produce a visually appealing weld, you should set the pulse at a frequency that is equal to or lower than one; follow this up by feeding the filler rod in accordance with the pulse. If you want to weld non-ferrous metals with high thermal conductivity such as aluminum, then you can use pulse welding to lower the weld’s overall heat. Additionally, this variant of welding will allow you to get a more penetrating weld without applying ‘too much’ heat to the weld.
The welding is performed by the peak current while controlled cooling is enabled by the low current. Although you will have a high peak current that allows more penetrating welds, you will have a lower average current with pulse welding which will keep the material cooler.
What are the advantages of pulse welding?
There are several advantages of pulse welding. These include (but are not limited to) wire and gas savings, reduced spatter and fume, heat reduction, improved productivity, and a better quality weld. Perhaps, the biggest advantage of pulse welding is that it reduces the overall heat generated in the weld. This improves the overall quality and appearance of the weld.
Another major advantage of pulse welding is that it reduces spatter which minimizes secondary operations and rework. Most of the cost-savings enabled by pulse welding come from a reduction in spatter. Additionally, this reduces the time needed to clean-up after the weld is complete.
Pulse welding improves productivity by providing higher deposition rates out-of-position. Additionally, welding with pulse welding is less complicated than other transfer methods which help to increase productivity. Finally, pulse welding can ensure a more stable arc and a better-quality finish than other transfer methods; this is what you ultimately want with any welding process.