 Manual arc welding  Heat for welding generated by electric arc established between flux-covered consumable metal rod (electrode) and work  Called stick electrode welding  Combustion and decomposition of electrode creases gaseous shield  Protects electrode tip, weld puddle, arc, and highly heated work from atmospheric contamination ▪ Additional shielding provided by covering of molten slag (flux) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

American Welding Society Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

 Shielded metal arc welding one of most used of various electric arc welding processes

 Equipment less complex, more portable and less costly  Can be done indoors or outdoors, in any location and any position  Electrodes available to match properties and strength of most base metals  Not used for welding softer metals  Not as efficient in deposition

 Sets up electric circuit  Includes welding machine, work, electric cables, electrode holder and electrodes, and a work clamp  Heat of electric arc brings work to be welded and consumable electrode to molten state  Heat intense: as high at 9,000ºF at center Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

 Electric arc started by striking work with electrode  Heat of arc melts electrode and surface of base metal  Tiny globules of molten metal form on tip of electrode and transferred by arc into molten pool on work surface  After weld started, arc moved along work

American Welding Society Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

 Each type of power source has fundamental electrical differences that best suit particular processes  Welding machine  Must meet changing arc load and environmental conditions instantly  Must deliver exact amount of electric current precisely at right time to welding arc  Available in wide variety of types and sizes

 Engine-driven generators  Powered by gas or diesel combustion engine  Can be found with a.c. or d.c. electric motor ▪ No longer being manufactured and rarely found  Transformer-rectifiers  Use basic electrical transformer to step down a.c. line power voltage to a.c. welding voltage  Welding voltage then passed through rectifier to convert a.c. output to d.c. welding current  May be either d.c. or a.c.-d.c. machines

 A.C. transformers  Used to step down a.c. line power voltage to a.c. welding voltage  Inverters  Increases frequency of incoming primary power  Constant current, constant voltage, or both  Produce a.c. or d.c. welding current

 Voltage generated by welding machine when no welding being done  Machine running idle  Arc voltage  Voltage generated between electrode and work during welding  Load voltage  Voltage at output terminals of welding machine when arc is going  Combination of arc voltage plus voltage drop in welding circuit

Hobart Brothers Co. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1. Sturdy steel lifting eye 2. Large voltmeter 3.Calibrated dial for easy, fine adjustment of heat and relation between voltage and current 4. Outer wheel and dial for selecting desired welding range 5. Stop button

Hobart Brothers Co. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6.Ground cable connector 7.Optional steel guard 9.Heavy-duty ball bearings 8.Pressed steel bearing cap 10.Arc welded copper squirrel cage rotor 11. Motor stator 12. Heavy steel fan

Hobart Brothers Co. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13.Steel frame 14.Fourpole "Multi-Range" generator 16. Large commutator 15. Heavy-duty metallic graphite brushes 17. Heavy-duty ball bearings 18.Pressed steel bearing cap 19. Arc welded steel frame

Hobart Brothers Co. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 20.Removable steel covers 21.Heavy-duty single unit steel shaft 23. Polarity switch 22.Welding cable connector 24. Large ammeter 25.Steel turret top with removable cover

 Electrode negative and electrode positive used in d.c. welding  DCEN (d.c. electrode negative)  Electrode connected to negative terminal of power source and work connected to positive terminal  DCEP (d.c. electrode positive)  Electrode connected to positive terminal of power source and work connected to negative terminal  Switch changes to either electrode positive or electrode negative

 Percentage of any given 10-minute period that machine can operate at rated current without overheating or breaking down  Rating of 100% means machine can be used at rated amperage on continuous basis ▪ Required by continuous, automatic machine welding  Rating of 60% means machine can be used at its capacity 6 out of every 10 minutes without damage ▪ Satisfactory for heavy SMAW and GTAW

Lenco dba NLC. Inc. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

 Generates heat for several major welding processes  Gas tungsten arc welding (GTAW)  Gas metal arc welding (GMAW)  Arc cutting utilizes much of same equipment as arc welding

 Welding heat comes from arc formed between base metal and carbon electrode or arc formed between two carbon electrodes  With or without addition of filler rod  Carbon electrodes available: 1/4, 5/16, 3/8 inch  Alternating current: amperes  Metal electrode holders not suitable  Carbon electrode hotter than metal electrode

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Lincoln Electric Co. Two leads are required because the arc is created between the two electrodes. Metal shield to protect welder's hand from intense heat. Larger than the metal electrode holder Holder is water cooled

 Now that you have completed your notes:  Watch the Short video that should appear under this podcast.  Then using this website which is off to the side of links as well complete the vocabulary sheet in your packet, but take the time to look at some of the links because there is some cool video, picture and graphics to go with it