1. Welding Processes

2.  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

3.  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

4.  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

5.  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

7.  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

8.  Directions for welded joints  Gives information for type of weld, size, process to be used, finishing processes, etc

13.  Weld symbols can be on either side of the reference line, each side is meant for a specific side of the joint