What is a welding power source or welder?
All arc-welding processes need a nonstop supply of electrical current in adequate quantity (amperage) and of correct voltage to sustain a welding arc. This current may be either alternating (AC) or direct (DC), but it must be provided to the welding electrode by using a device that enables its precise control. Only when the welding current is cautiously controlled, we can have the best welding arc characteristics and thus maximum welding efficiency – be obtained. This controlling device is called a Welding Power Source or Welder or Welding Machine.
Type of polarity and Welding process
The following are helpful tips to select the proper welder (power source) based on the type of welding current:
DC Welder (DCEP Power source) are used with the following welding process & Stick welding electrodes classification:
1. GMAW (Gas metal arc welding) also called MIG-MAG Welding
2. FCAW (Flux-cored arc welding) either FCAW-G or FCAW-S
3. Exx60 type electrodes e.g. E6010, E7010
4. Exx15, EXX18 type electrodes e.g. E7015, E8015, E7018
DC Welder (DCEP Power source) are preferred for:
1. Fast freeze applications
2. Fast follow applications
3. Welding stainless steel
4. Nonferrous electrodes
5. Surfacing with high alloy electrodes
AC Welder (AC Power Source)preferred for:
1. Fast fill applications
2. Iron powder electrodes except out of
3. position welding
4. Where arc blow is a problem 5. Aluminum Welding
Alternating Current or Direct Current depending on the application is used with:
1. GTAW (Gas tungsten arc welding) also called TIG Welding
2. SAW (Submerged arc welding).
Types of Welding Machine or Welder
Different types of welding machines are used in industries. These machines provide welding current & voltage for a broader range to suit various welding needs. The currents supplied through the power source may range from less than 10 amperes to 1500 ampere & voltage from 10 volts to 40 volts, or more, for example, a higher current for automatic welding. Based on power type, polarity types, and functions, the Welding Power source or welder are classified into:
- Welding Transformer
- Welding thyristor
- Welding Rectifier
- Welding Converter
- DC Generator
- Switched mode power supplies
Now, all the welding machines no matter for which welding process is based on these above 4 types. Further, based on the welding process the welding machines types used for welding operation in industries are:
- Stick Welding or SMAW Welding Machine
- Gas welding Machine
- TIG Welding Machine
- MIG-MAG or FCAW Welding Machine
- SAW Welding Machine
- Plasma arc Welding Machine
- Laser Welding machine
- Resistance Welding Machine
- Stud Welding Machine
- Plastic Welding Machine
- Friction Welding Machine
- Projection Welding Machine
- Electron Beam Welding Machine
- Electroslag welding Machine
- Seam Welding Machine
- Flash Welding Machine
- Ultrasonic welding Machine
- Spot Welding Machine
Types of Welding Machine or Welder based on Electrical/ Electronic characteristics
Transformer Welder (AC Transformer power Source)
A transformer welder is a voltage step-down transformer that changes high voltage, low-amperage AC input current to low voltage, high-amperage AC welding current. Transformer welders generally run on single-phase power. Most AC power made in the United States is 60-hertz, and each time the polarity changes the voltage goes through zero, which tends to create an unstable condition in the arc. This problem, however, has been solved by designing better brief characteristics in the welder and better AC electrodes. An example of a welding transformer is shown in the below figure.
In a welding machine, the Rectifier converts input AC to output DC so it can have negative and positive polarity. A single-phase rectifier welder is a transformer welder with a rectifier added to obtain a DC output. The output characteristic can be either constant or variable voltage. Welders or welding machines built using rectifier technology for MIG-MAG welding have controls for adjusting the current, voltage, and polarity for good welding performance.
Rectifier welder is the step-down transformer, in which three-phase AC is fed to rectifier units which, in turn, feed DC to a single output circuit. The output in a welding rectifier is always direct current (DC). This can be either constant, or variable DC.
Rectifier uses either diode or thyristor or transistors for converting the AC to DC for welding output. Direct current (DC) offers to use welding polarity for welding operations either DCEP (Direct current electrode positive) or DCEN (Direct current electrode negative). A choking device at the end allows current and voltage adjustment.
The DC motor-generator welder is driven by AC utility power. DC Generators are useful for field welding application such as welding of cross-country pipelines or in mines. They provide both constant and variable DC for welding. The DC generator motor is generally a three-phase induction motor. Usually gasoline is required to run the DC generator.
Welding Analog Power Supply
Analog power supplies are the latest technology in welding power sources by using dedicated and sophisticated electronic circuits. This allows very fine-tuning of welding parameters such as current, voltage, arc length, type of current, pulse current output, and storing the welding programs in the welder database. These machines also offer synergic welding supply.
A single welder (welding machine) can be used for AC, DCEP & DCEN along with pulse welding parameters controls, thus allowing good welds. Although, the cost of such machines is very high compared to others such as welding transformers or welding rectifiers.