Amperage is another critical component of the MIG welding processes. Amperage control the amount of heat that is applied to the metal as well as the depth to which the weld will penetrate. Using too much amperage can result in the weld melting through a metal.
Using too little amperage will prevent the weld from fuse with the metal. The amperage of the weld is the measure of the electrical current that is used in the weld. The amperage has to be balance with the voltage and the wire feed speed settings in order to create a good weld.
How Amperage Affects MIG Welding
The wire diameter that is used will determine the maximum amount of amperage that can be used in the weld. Thinner welding wire is used in situations where thin metals is to be welded together. Thin wire is not appropriate for using high amperage settings because the thin wire will overheat.
Thicker welding wire is used for metal that is thicker and allows for more higher amperage settings to properly fuse the metal pieces together. The wire diameter will determine the amperage settings, so the wire has to be appropriate for the metal that is being welded. Amperage works in conjunction with the voltage and the wire feed speed settings.
These three settings has to be balanced with one another to produce a good weld. The wire feed speed will determine the amperage settings. Higher wire feed speeds will mean higher amperage settings.
A general rule of thumb for wire feed speed and amperage is to use one amp for every thousandth of an inch of metal thickness. However, these settings have to be tested on scrap metal prior to begin to weld the metal that will be used in the project. The type of shielding gas that is used will impact the amount of amperage that is used in the weld.
Argon and carbon dioxide gas mixtures are used for steel welding as they will reduce the amount of spatter that is created from the welding process. If pure carbon dioxide is used, the penetration of the weld will be deeper into the metal but there will be more spatter to clean up. For welding aluminum metal, pure argon gas have to be used for welding.
Using any other type of shielding gas will lead to poorly weld quality. The amount of amperage that is used in the welding process will determine the type of metal transfer mode that is used for the weld. Short circuit transfer mode uses low amperage settings.
This mode is used for thin metal as well as metal that has to be welded in overhead positions as the weld puddle will freeze quick at low amperage settings. Globular transfer mode uses higher amperage settings but creates a lot of spatter. Spray arc mode uses high amperage settings but allows for faster metal welding on flat metal pieces.
Voltage has to be adjusted according to the amperage settings to control the metal transfer mode. The type of metal that is being welded will require different amperage settings for the weld to fuse properly. Mild steel metal accepts the standard amperage settings.
For aluminum metal, due to the high rate at which it conducts heat, twenty to thirty percent more amperage is used when welding aluminum metal as compared to mild steel metal. For stainless steel metal, the heat is retained differently than in mild steel so the amperage has to be adjusted so that the stainless steel metal does not warp during welding. In vertical or overhead metal positions, fifteen to twenty percent less amperage is used as excessive amperage may cause the metal to fall out of the weld due to the force of gravity.
Welding problems can be identified by observing the results of the amperage settings. If the metal melts through the joint, the amperage needs to be decrease or the metal travel speed should be increased. For welding with excessive spatter, the welding voltage settings need to be adjusted in relation to the wire feed speed settings.
Porosity can be caused by issues with the shielding gas or metal cleanliness so these components should be inspected. If the welding wire becomes tangled on the drive rolls, the tension settings is too high. High tension settings can prevent proper amperage from being delivered to the weld area.
In order to maintain a stable welding current, the stick-out distance should be maintained between three-eighths and one-half inch. If the metal to be welded is thick, it should be preheated to help it fuse without using such high amperage settings. Finally, prior to welding metal that will be used in a project, it is important to test the weld settings on scrap metal to ensure that the weld settings are correct.
