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Welding Basics 101
Arc "Stick Welders - Wire Feed - Oxy-Acetylene - Quick Course - Helmets - Safety
|Welding is basically a method of melting two sections of metal together with the use of an electric arc or gas flame and at the same time melting a wire rod into the joint for additional strength. To sheild the metal from oxidizing as it is being welded either a flux coating is added to the wire rod or a gas is expelled from the welding tip.
Three types of welders are usually found in home workshops, stick, wire-feed or oxy-acetylene, each has its advantages, most shops will have either a stick welder or a wire feed for welding and an oxy-acetylene torch for brazing and cutting.
Stick welders use a consumable rod, about a foot long, with a flux coating, the rod is clamped into the electrode holder, a ground is clamped to the metal and an arc is made when the rod comes in contact with the metal. The trick to using a stick welder is to keep a gap between the tip of the rod and the metal, if the rod is too close it will weld its self to the metal, too far away and it will lose the arc. The arc is made by "striking" the rod against the metal, establishing the arc and holding it far enough away to maintain a steady arc, then moving along at a rate to fill the gap made by the arc. This takes practice and one must also know what heat setting to use in relation to the thickness of the metal to make a strong weld. There are both 110 volt and 220 volt models, however for satisfactory results a 220 volt welder is pretty much a necessity.
Wire feed welders have become more common in home workshops in the last few years due to the availability of smaller low priced models now in the market place. A continuous wire is fed from a spool, the wire may be flux coated, or a bottle of gas can be connected to the welder and an uncoated wire used. These welders are much easier to use than a conventional stick welder, after an hour or two most handymen can make an acceptable weld. They also add flexibility, many types of metals can be welded simply by changing the type of wire used. Another big advantage is that your shop does not fill up with smoke and fumes like when you use a stick welder. Wirefeed welders will perform very well on basic 110 volt household power so there is also the advantage of portability.
MIG stands for metal inert gas also referred to as GMAW-welding (Gas Metal Arc Welding). This inert gas, helium or argon, flows out of the gun and keeps the weld puddle shielded from the atmosphere.
TIG-welding (Tungsten Inert Gas) or GTAW-welding (Gas Tungsten Arc Welding) uses a permanent non-melting electrode made of tungsten. Filler metal is added separately, which makes the process very flexible. It is also possible to weld without filler material.
TIG Welding Tips - From Miller
Oxy-acetylene welders are commonly referred to as cutting torches, they are a dual purpose unit, used for both welding and cutting. By using the proper tips, rods and fluxes, almost any metal can be welded, heated or cut using the Oxy-Acetylene process.
When welding the flame is applied to the base metal and held until a small puddle of molten metal is formed. The puddle is moved along the path where the weld bead is desired, more metal is added to the puddle as it is moved along by means of dripping metal from a wire rod.
A cutting torch has a 90-degree angled head with six orifices placed around a central jet. The six outer jets are for oxygen and acetylene and the central jet carries only oxygen. The torch's trigger releases extra oxygen at high pressure down the torch's third tube out of the central jet into the workpiece, causing the metal to burn and blows the resulting molten oxide through to the other side and off the workpiece completely.
Brazing is a process where molten bronze is used to join steel, cast iron or any ferrous metal without melting them. It is actually more similar to soldering than welding but requires the high heat of an oxy-acetylene torch rather than a propane torch.
Oxy-Acetylene Welding and Cutting by Harold P. Manly - Free eBook from Project Gutenberg
Striking an arc is like striking a large match, with your helmet up, position your electrode about 1/4 inch away from where you want to start welding, lower your helmet and make a quick jab with the electrode. Watching for the arc, be prepared to pull the electrode away slightly. You will have to slowly move the electrode into the weld pool.
The bright light of an arc welder requires the use of eye protection which is provided by a helmet with dark colored lens, one problem is that when the helmet is worn there is no amount of visibility until the arc is struck so you are basically working in the dark. This is overcome in three ways, flip up helmets, flip up lens only and auto darkening lens.
Oxy-Acetylene torches are not as bright as arc welders so do not require really dark lens, so there is still some visibilty when wearing them, just don't ever use them for arc welding.
Whether the heat comes from an electric arc or a gas flame there is a bright light created that requires eye protection, for arc welding a full helmet covering the face is used, for oxy-acetylene goggles over the eyes are used. Always use the proper equipment that will give adequate protection to prevent serious damage to your eyes.
Protect your entire body with fire retardant clothing, shoes, and gloves.
Welding and cutting both create hot sparks, make sure there are no flammable substances or objects nearby, because you are wearing eye protective equipment and concentrating on what you are doing you may not notice small fires until they are well established and out of control.
Never weld without adequate ventilation.
Welded metal is very hot, use gloves when welding and tongs to handle the hot parts.
Remove batteries from autos or machinery before welding in their vicinity, batteries emit hydrogen which is very explosive.
Wear eye protection when chipping slag from the weld.
Never do welding on gas tanks, used drums or containers of any kind.