This Instructable will provide a short introduction to the process of MIG welding, as well as a step by step procedure in welding three common joints. Welding can be used by anyone from beginners to experts in order to effectively join two pieces of metal. By understanding different weld joints, the possible uses for welding increases. With access to a welding machine you will be able to benefit from this tutorial and add welding to your collection of skills.
Welding is the act of joining two or more pieces of metal by melting and joining them with a filler metal.
The welded metal is melted by means of an electrical current that arcs between the welding gun and the workpiece. In the image, the gun is what is being held by the operator, and the arc is clearly visible. The heat produced by the arc melts both the base metal and the filler metal. The area consisting of melted base and filler metal is referred to as the weld bead. When the bead solidifies, the metal has been joined together.
WHY USE WELDING?
Welding can be used for a multitude of different manufacturing applications and is used for the quality and speed in which it can join metal. There are several different types of welding, all with advantages, disadvantages, and specific areas of use. For example TIG or GTAW (gas tungsten arc welding) can be used for applications requiring high quality and control over the weld bead, while stick welding is used for its versatility, portability, and speed. The type of welding that will be used in this instructional document is MIG or GMAW (Gas metal arc welding). MIG is one of the most widely used forms of welding in industry and is considered one of the easier forms of welding to learn. Anyone with access to a welding machine can take advantage of this manufacturing process.
Step 1: Equipment
WIRE FEED SYSTEM
MIG welding uses filler metal that will continuously feed through the welding gun (torch) as it is melted. The filler metal (or electrode) takes the form of a long thin wire and carries the current that arcs to the base metal. When the trigger is pulled on the gun, the wire electrode will feed out of the tip. Pulling the trigger also activated the electricity, supplying the current.
Without shielding the molten metal in the weld pool is subject to atmospheric gases, causing defects. In order to prevent this a form of inert gas is used to shield the area directly around the weld bead; this system is built directly into the welding machine. It is not necessary to know the specifics of this system, but it is important to know that shielding gas is involved and where the storage tank is located.
The figure shows the basic components in the MIG welding system.
1. The welding torch/gun
2. The workpiece or base metal
3. The electrical power supply
4. The feed unit
5. The electrode (filler metal) source
6. The inert shielding gas source