Types of Welding Electrodes explained
Welding electrode is mainly classified into two broad categories
1. Non-consumable electrodes and
2. Consumable electrodes
Non-consumable or Refractory Electrodes
- While welding with these electrodes a filler metal is needed to fill up the gap between the two metal parts.
- These are used in carbon arc welding and Tungsten Inert Gas (TIG) welding .
- Tungsten electrodes are much costlier than carbon or graphite electrodes. Tungsten alloy electrodes are costlier.
- these are more thermally efficient than non consumable electrodes.
- They are made of different materials depending upon the need and the chemical composition of metals to be joined.
- These are used in MIG welding in the form of bare electrode.
- Most commonly used core material is mild steel, low alloy steel and nickel steel.
1. Bare electrodes: They don't have any flux coating only the alloy or the metal wire.
2. Light coated electrodes: These are electrodes having coating factor of 1.25 . coating factor = diameter of the electrode / diameter of the core wire .
example : Citobest electrode from AO or Advani Oerlikon.
3. Medium coated electrodes: These have coating factor of about 1.45 .
example : Overcord
4. Heavily coated electrode : Coating factor is between 1.6 and 2.2 . example : citofine .
Covered electrodes can be classified as follows :
- electrodes having cellulose
- Rutile (titania)
- Electrode having iron oxide
- Electrode with iron powder
- Low hydrogen electrode
Welding Electrode Explained in details
- Need of filler metal
- Core Wire composition
- The size and length of the welding electrode
- Current Requirements
- Specification of the welding electrodes
Specifications for electrodes and for filler metals, including dimensional tolerances, quality control procedures, and processes, are stated by the American Welding Society (AWS) and the American National Standards Institute (ANSI); some appear in the Aerospace Materials Specifications (AMS) by the Society of Automotive Engineers (SAE).
- Welding electrode numbering system
Electrodes are identified by numbers and letters (Table 27.2), or by color code, particularly if they are too small to imprint with identification.
(a) the wire diameter must not vary more than 0.05 mm (0.002 in.) from nominal size, and
(b) the coatings must be concentric with the wire.
Welding Electrode is sold by weight and are available in a wide variety of sizes and specifications. Selection and recommendations for electrodes for a particular metal and its application can be found in supplier literature and in the various handbooks