Welding

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Welding

• Mr. Wisness

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What is welding?

• Joining two or more pieces of metal together by
  the fusion process

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Importance of Welding

• 50 of Gross National Product of the country is
  related to welding
• Almost everything made of metal is welded

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How is welding used in Industry

• Railroad freight cars
• Trans-Alaskan pipeline
• Elevated storage tanks for water
• Patio chairs
• Sears Tower
• Automobiles
• Collision Repair Work

• Space Program
• Airplanes
• Coffeepots
• Bridges
• Furniture
• Jet Engines
• Yachts
• Construction Equipment

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Career Opportunities

1. Building Construction
2. Bridge Highway Construction
3. Automotive Industry
4. Ship Building
5. Aircraft Industry
6. Self-Employed Business Owner

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How is welding used in Agriculture?

• Essentially all farm equipment is welded together
• Tractors
• Bobcats
• Combines
• Trailers
• Repair and maintenance of buildings and equipment

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Types of welding
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Oxy acetylene welding

• Two gases involved
• Oxygen
• Acetylene
• Compound of Carbon and Hydrogen
• Colorless (but not odorless)
• Flammable
• Combined with oxygen produces hottest flame
  temperature

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Equipment used for Oxy-acetylene welding

• Acetylene tank, hose and regulator
• Oxygen tank, hose and regulator
• Welding torch body
• Cutting assembly with tip
• Wrenches to fit connections
• Safety goggles

• Tongs for handling hot metal
• Welding table
• Flint Lighter
• Coveralls
• Gloves

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MIG Welding

• Metal Inert Gas
• Also known as GMAW
• Gas Metal Arc Welding
• Uses a continuous solid wire electrode for filler
  metal
• Uses an externally supplied gas for shielding

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Shielded Metal Arc Welding

• Stick Welding
• Flux covering electrode melts during welding
• Forms the gas and slag to shield the arc and
  molten weld pool.
• Slag must be chipped off the weld bead after
  welding

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TIG Welding

• Tungsten Inert Gas
• Also called Gas Tungsten Arc Welding (GTAW) 
• An arc is formed between a nonconsumable tungsten
  electrode and the metal being welded
• Gas is fed through the torch to shield the
  electrode and molten weld pool. 
• If filler wire is used, it is added to the weld
  pool separately. 
• Has become a popular choice of welding processes
  when high quality, precision welding is
  required. 

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Five Basic Joint Types

• Butt
• Corner
• Edge
• Lap
• Tee

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Welding Positions

• Flat
• Vertical
• Overhead
• Horizontal

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Kinds of Welds

• Fillet
• Groove
• Bead

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Welding terms

• Weldment
• An assembly whose component parts are joined by
  welding
• Joint
• The junction of members or the edges of members
  that are to be joined or have been joined
• Tack weld
• A weld made to hold parts of a weldment in proper
  alignment until the final welds are made

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Welding Terms

• Base Metal
• The material to be welded, brazed, soldered or
  cut
• Filler Metal
• The metal or alloy to be added in making a
  welded, brazed or soldered joint
• Autogenous
• Filler metal is not used

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Welding Terms

• Coalescence
• The growing together or growth into one body of
  the materials being welded
• Fusion
• The melting of metals until the molten portions
  unite with each other
• Crater
• Depression at the end of a weld

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Backfire

• A loud pop which occurs while welding with the
  oxyacetylene process
• Causes may include
• Touching tip against work piece
• Flame setting too low
• Loose or dirty tip
• Damaged seals inside torch

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Welding Terms

• Electrode
• Metal rod which conducts a current from the
  electrode holder to the base metal
• Arc
• The flow of current across a narrow gap
• Face
• The exposed surface of a fusion weld

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Welding Terms

• Bead Weld
• Made by one pass of the electrode
• Pads
• The metal plates which have beads running
  parallel to each other in such a way that the
  beads are united with one another to form a solid
  mass
• Bevel
• Type of edge preparation

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Welding Terms

• Consumable Welding Arc Process
• A welding process in which the electrode is
  consumed in the welding process
• Non-consumable Welding Arc Process
• Electrode does not melt in the arc, and filler
  metal is not carried across the gap

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Welding Terms

• Flux
• Material used to prevent, dissolve, or facilitate
  removal of oxides and other surface substances
• Kerf
• The width of the cut produced during a cutting
  process
• Spatter
• The metal globules expelled during metal arc
  welding and which do not form a part of the weld

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Welding Terms

• Penetration
• The distance from the original surface of the
  base metal to the point at which fusion ceases
• Porosity
• A condition which is caused by a gas pocket being
  trapped in a weld as it solidifies
• AWS
• American Welding Society

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SMAW Benefits

• Equipment used is simple, inexpensive, and
  portable
•  Electrode provides and regulates its own flux
•  Lower sensitivity to wind and drafts than gas
  shielded welding processes
•  All position capability

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MIG Welding Benefits

• All position capability
•  Higher deposition rates than SMAW
•  Less operator skill required
•  Long welds can be made without starts and stops
•  Minimal post weld cleaning is required

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TIG Welding Benefits

•  Superior quality welds
•  Welds can be made with or without filler metal
•  Precise control of welding variables (heat)
•  Free of spatter
•  Low distortion

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Advantages of Oxy-acetylene welding

• Equipment is very portable
• Relatively inexpensive
• Can be used in all positions
• Pool is visible to welder

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Welding is fun!

• But Safety Always Comes First!