To complete any welding job, there are certain arc welding tools that will be necessary. A welding rod consists of two parts that include an electrode and a clamp. To use, an electric current passes through it and the rod melts creating an electric arc. Different rods are used for different types of metals.
A welding rod consists of two parts:
Metal core – The central part of the rod
Brittle Coating – surrounding the core.
The core needs to match the type of metal being welded. The coating is the main element that is responsible for acting as a primary electrical conductor for priming, protecting the arc during welding, orients the arc according to the welding position whether that be flat, rising, falling, or raised, and protects the pool of molten metal by forming a slag that rises to the surface.
Types Of Electrodes
Three types of rod coating are used to weld metals like carbon steel, stainless steel, cast iron, or an alloy. These coatings are rutile, basic, and cellulosic.
Rutile Coating – Sometimes called acid, rutile coating is the most often used. It can be used flat or at an angle to produce an attractive weld. The electrode diameter will depend on how thick the parts that need to be welded are. Choose products that are labeled as “all positions” for common use.
Basic Coating – For use by professionals, boilermakers, and welders. It can be used for all welding positions and performs well but is fragile. Basic coating must always be kept dry and preheated before using.
Cellulosic Coating – Usually used for pipes with its thin, fine coating. Cellulosic coating is not for the beginner.
Stainless Steel Electrodes – To weld stainless steel, cast iron, or hard steels, specialized electrodes may be required. Special handling will be necessary since these type of electrodes are prone to sticking. Also, protective goggles and a welding hood will be needed.
Cast Iron Electrodes – This type of electrode will need to be preheated and welding parts cooled slowly surrounded by sand or hot gravel to keep them from cracking. Handle with extreme caution.
Self-Hardening Electrodes – Made for hard steels or to resharpen blunt cutting tools. Self-hardening electrodes are expensive.
Rutile Electrodes – The most common type of electrode.
Achieving the proper welding technique takes a lot of practice. Professionals and experienced do-it-yourselfers have a feel for it. When connecting edges, chamfering is required. Simply put, there needs to be a bevel cut on each edge to form a “V-shape” that is filled with electrodes upon the first pass and then refilled with a larger-diameter electrode on the second pass. The process allows the core to be welded for a solid assembly. When the sheet of metal is extremely thick, semi-automatic welding will be done. When a weld overlaps or is at an angle, you can make a first pass with a smaller diameter rod to fill in the corner entirely before continuing with a larger diameter rod.
Polarity refers to the choice of electrical connections for the electrode clamp and earth cable. Simply put, you are able to plug your torch into the positive or the negative. Since the connectors are identical, you will be able to place the electrode at the positive DC+ or negative DC- pole depending on the type. Generally, rutile rods need to be connected to the negative, while basic rods need to be connected to the positive pole. For stainless steel electrodes, choosing DC+ will create less heating.
Often, a crater forms at the beginning and the end of the welding by the electric arc. To avoid this, use two pieces of scrap metal. Place them at the top and bottom of the weld, and start welding on these martyr pieces. Immediately take them to the grinder.
There are four basic welding positions:
- Flat – The most basic
- Cornice – The piece is vertical, while the weld is horizontal
- Vertical – Positioned up and down
- Overhead – The hardest welding position because the welder is located underneath the piece being welded.
Always use protection! (Don’t weld without a mask, that is!) Additionally, carefully collect the end of the rod that stays in the clamp when the electrode is burned up and place it in a metal box or tin can so as not to cause a fire. Make sure the work space is well ventilated.