The Mosfet inverter Mig welder machine is made up of a CV - Constant Voltage power source. The inverter rectifies the incoming AC into DC - direct current. This Direct current power is then filtered via capacitors prior to being fed to the inverter matrix. The output is then changed into DC and becomes the main welding current. At this point you wire feeder that is used to push metal wire into the welding arc. Because the welder is CV - constant voltage it will maintain a specific length of welding arc within the range set on the main panel by the operator. With technologies such as Mig welders you weld with voltage and not amps although both are present and inter related.By now you are starting to comprehend the principle behind inverter welder machines and how it is used within to the two main types of systems CC and CV. An arc welder for example is just like a Tig welder as it is CC however it uses a manually held electrode. Spot welding is a process in which contacting metalic surfaces are joined by the heat created from resistance to electricity. Work-pieces are held together under pressure exerted by electrodes. Usually the sheets are in the 0.5 to 3 mm (0.020 to 0.12 in) thickness range. The process uses two shaped copper alloy electrodes to force electrical energy into a small area and it simultaneously clamps the sheets against each other. Focusing a huge current through the contact point will join the metal and form the weld. The disireable feature of spot welding is that an abundance can be delivered to the spot in a very short time (approximately ten milliseconds). That permits the weld to happen without excessive heating to the rest of the material.