Joining is an all inclusive term, which covers processes such as welding, brazing, soldering, adhesive bonding, and mechanical joining. These processes are an important and necessary aspect of manufacturing operations. This paper deals with one topic in particular ˜Welding'.
Welding is a process for joining similar metals. Welding joins metals by melting and fusing 1, the base metals being joined and 2, the filler metal applied. Welding employs pinpointed, localized heat input. Most welding involves ferrous-based metals such as steel and stainless steel. Welding covers a temperature range of 1500 º F - 3000 º F (800 ºC - 1635 ºC). Weld joints are usually stronger or as strong as the base metals being joined. Typically, welding is used for forging, farrier, blacksmithing, oil pipelines, and food equipment applications.
Now, let us go into Welding in more detail. There are a number of different types of welding.
Oxyfuel gas welding (OFW) includes any welding operation that uses combustion with oxygen as a heating medium. The process involves melting the base metal and usually a filler metal, using a flame produced at the tip of a welding torch. Fuel gas and oxygen are combined in the proper proportions inside a mixing chamber which may be part of the welding tip assembly. Molten metal from the plate edges, and filler metal, if used, intermix in a common molten pool and coalesce upon cooling. One advantage of this welding process is the control a welder can exercise over heat input and temperature, independent of the addition of filler metal. Weld bead size, shape, and weld puddle viscosity are also controlled in the welding process. OFW is ideally suited for repair welding and for welding thin sheet, tubes, and small diameter pipe. Thick section welds, except for repair work, are not economical when compared to the many available arc welding processes.
The most common gas welding process uses acetylene fuel and is cal