Welding

Mr. Wisness

What is welding?

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

Importance of Welding

50 % of Gross National Product of the country is related to welding

Almost everything made of metal is welded

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

Career Opportunities

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

How is welding used in Agriculture?

Essentially all farm equipment is welded together– Tractors– Bobcats– Combines– Trailers

Repair and maintenance of buildings and equipment

Types of welding

O xy-ace tylen eW eld in g

S h ie ld ed M eta lA rc W e ld in g

S M A W

G M A WG as M eta l A rc W e ld in g

M IG W eld in gM eta l In e rt G as

Typ es o fw e ld in g w eare g o in g to

d o in th is c lass

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

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

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

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

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. 

Five Basic Joint Types

Butt Corner Edge Lap Tee

Welding Positions

Flat Vertical Overhead Horizontal

Kinds of Welds

Fillet Groove Bead

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

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

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

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

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

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

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

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

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

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

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

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

Advantages of Oxy-acetylene welding

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

Welding is fun!

But Safety Always Comes First!