Pulse Welding. What is it?
Pulse Welding in Simple Terms.
In its simplest form pulse welding is welding with a welding current that constantly changes from a high (peak) amperage down to a low (basic or background) current and back again. This allows for welding thinner metals and high heat conductive metals without burning through. On thicker metals you can achieve tighter narrower more penetrating welds.
Pulse Welding in Less Simple Terms.
Explanation of Pulse
Depending on the cost and complexity of the welder you have, you can have a high degree of control over the pulse welding capabilities of your welder. Through electronics they can allow you to change many of the characteristics of the pulse waveform. Setting the Peak Amperage sets the high amperage of the pulse. This will normally be higher than if you were welding without pulse as your real amperage will be the weighted average of the peak current and the background or low current setting. Next you will set the background current setting. This is more often a % of the peak current rather than an actual amperage. This means as you change and adjust the peak current the relationship or ratio to the background current will remain the same. For instance if you set the welders peak current at 100 amps and the background current at 40% then the background current will be 40 amps. If you change the the peak amperage to 150 amps the the background current will become 60 amps if you do not change the background current setting. Common settings for the background current settings are in the area of 30-60%. The background or low current is also used to harden the molten metal but not so severely than going zero amps.
Pulse frequency is how often the welding amperage changes from high to low in a second. Set at 0.5 it will pulse once every two seconds and set at say 100 it will pulse up and down 100 times a second. Setting the pulse around 3 or less times a second or above 30 times a second is easier on the eyes. In between those frequencies the strobe effect can be quite discomforting. Find where your own tolerance levels are at. At lower pulse frequency settings of 1 per second or less, it is easy to feed the filler rod in sync with the pulse. This can help achieve a more uniform ascetic weld. Higher pulse settings per second for increased metal thickness is the rule of thumb. Low pulse settings are recommended for thinner metals. For example 3mm steel you might use 50 pulses per second or less and on 12mm steel a 100 pulses per second might be more suitable. There are many other opinions on what these settings should be so just use these suggestions as a starting point.
This sets the balance between the time at the peak current level and the background current level in pulse mode. 50% is equal time high and low. On TIG welders that do not offer control of this setting 50% pulse duty will normally be the fixed setting.
Sets the power slope down time taken after the torch trigger is released, this is the time for the power to reduce from the set welding current to zero. This is important for welds that terminate at the edge of material and helps prevents burn through.
Gas Pre Flow and Post Flow
In order to purge the area to be welded, you can set the gas to start flowing before you strike an ARC. This will purge the start area of the weld to ensure a good starting weld. The post flow setting allows gas to continue to flow after you have stopped welding. This allows the weld to congeal in the proper atmospheric conditions. Once you have released the trigger and welding has stopped, you must hold the welding torch in position over the weld until the gas stops flowing.
When to Use Pulse Welding?
In out of position welding, pulse welding helps the weld congeal during the background cycle preventing the molten metal from dripping out of the joint. It is recommended for welding thin metals when the risk of burn through is higher. If you need a more attractive looking weld then setting the pulse frequency at one or lower and feeding the filler rod in sync will give a very pleasing effect. If you are welding non ferrous metals like aluminium (AC welding mode required) that have a high thermal conductivity then pulse is very useful for lowering the overall heat generated in the weld. Pulse welding will help you to get deeper penetration without putting as much heat into the metal. The peak current does the welding and the background current allows for controlled cooling. Whilst your peak current may be high and allow for greater penetration your average current will be lower and thus your material will be cooler.
The TIG Welding Foot Pedal
You can use a foot pedal to control pulse at a low frequency rate of about one per second. However, by doing this your background current will be quite varible until you get a good rythem.
Setting up at pulse welding is up to the individual user. Find a scrap of metal and start practicing and testing different settings. Getting your settings correct in pulse welding will greatly improve the quality and appearance of your welds.SIP P214HF TIG/ARC Inverter with Pulse