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Welding Processes. Chapter 18. Welding. The process of joining two or more pieces of like metal Parts are heated enough to cause it to melt where they meet When the metal cools it solidifies, joining the parts Properly welded joints are as strong as or stronger than the original material
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Welding Processes Chapter 18
Welding • The process of joining two or more pieces of like metal • Parts are heated enough to cause it to melt where they meet • When the metal cools it solidifies, joining the parts • Properly welded joints are as strong as or stronger than the original material • Considered a permanent fastening method
Welding Processes • All processes shown on page 673, fig 21.3 • Most common types: • Oxygen Gas Welding • Oxyacytlene welding (2 tanks) fig 21.4 • Can be used with: natural gas, propane, propylene • Typically used to fabricate thin materials • Used mostly for repair work (portable) • Can also be used to cut • Low operating cost • Slower than other processes
Also associated with brazing • Brazing is considered bonding • Base materials remain solid while the filler material melts then cools to bond the pieces together • Shielded Metal Arc Welding (stick welding) • Most traditionally used process • Used on a variety of metals • Used a flux covered metal electrode to carry electric current that forms an arc to melt the metal • Electrode also melts and joins the melting base materials to form the weld
Gas Tungsten Arc Welding • Tungsten inert gas welding (TIG) • Can be used on a wider variety of metals • Produces clean high quality welds • Usually limited to thin parts that need high quality joint • Slow process • High cost for equipment and materials • Gas Metal Arc Welding (MIG) • Very fast and economical • Used on thin or thick materials • Used in mass production
Welding Drawings • Typically called weldments or welding assemblies • Shows parts together in multi-view • Contains : Fabrication dimensions Types of joints Weld symbols • Parts are shown as separate pieces on the drawing (don’t unite solids) • All parts may not be dimensioned completely • May have separate detail drawings
Weld Symbol • Directions for welded joints • Gives information for type of weld, size, process to be used, finishing processes, etc
Side Significance • Weld symbols can be on either side of the reference line, each side is meant for a specific side of the joint