A14 Part 2

Front 1

SMAW

Back 1

Shielded metal arc welding. An electric arc that develops when an electric current is forced to leap a small gap in the circuit

Also commonly called stick welding

Front 2

Pressure and Voltage

Back 2

Pressure created by generator. Also called voltage and measured in volts (v)

Flow of electricity is called current and measured in amperes (a)

Front 3

SMAW Welding Circuit

Back 3

Consists of:

1. A welding power source

2. A work piece lead cable and ground clamp

3. An electrode lead cable

4. A welding electrode and electrode holder

5. The work piece

Front 4

Arc Path

Back 4

Circuit completed > Current > Electrode > Arc >Workpiece > Ground Clamp > Work place lead > Back to power source

Front 5

Open Circuit Voltage

Back 5

Power source for circuit on but no arc has been struck. Highest voltage generated

Front 6

Arc Voltage

Back 6

Circuit close resulting in drop of voltage. Is also the current that flows through the entire welding circuit

Front 7

SMAW Heat

Back 7

Heat generated is 5500 - 6600 c

Front 8

Applications of SMAW

Back 8

1. Shipbuilding

2. CT and automotive

3. Industrial and Agricultural

4. Engineering Applications

5. Boiler and Pressure Vessels

6. Piping and Pipelines

7. Bridge Building

8. Building and Structural

Front 9

PPE

Welding Helmets

Back 9

Shade depends upon the intensity of the arc. Higher intensity requires a darker shade

Front 10

PPE

Arc Burn

Back 10

Infrared and UV radiation that arc welding can damage eyes and skin. Proper PPE such as flame resistant clothing must be worn

Front 11

Electric Shock

Back 11

SMAW generates currents strong enough to severely hurt or kill you.

Know how to d/c machine.

Front 12

Electrode Studs

Back 12

Electrodes can be used down to a length of 50mm or 2inches. Should be disposed of in a fire proof metal container.

Front 13

Ventilation

Back 13

Booths or welding stations should be equipped to extract harmful fumes at 2.8m3/min

The pickup duct must be located so fumes cannot reach welders face

Front 14

Alternating Current

Back 14

An electric current that reverses its direction many times a second at regular intervals, typically used in power supplies.

Front 15

Single Phase Alternating Current

Back 15

Most useful for domestic and light industrial operations.

Has a considerable amount of time where peak power is not utilized

Front 16

Three Phase Alternating Current

Back 16

Made up of 3 single phase at measured intervals to allow one of the three phases to be supplying maximum power at a given time.

Best used for industrial settings

Front 17

Direct Current

Back 17

The electrons in the current flow steadily from the negative pole to the positive pole.

Front 18

GMAW

Back 18

Gas Metal Arc Welding

Front 19

FCAW

Back 19

Flux Cored Arc Welding

Front 20

GMAW Principle

Back 20

An electric arc is drawn between a filler metal electrode and the base metal. The heat from the arc melts the end of the wire and area of base metal while shielding gas protects the arc from contamination

Front 21

Main Components of GMAW

Back 21

1. DC power source

2. Welding gun with hose and cables

3. Feed mechanism for wire with contractor

4. Shielding gas system with hose and flowmeter

5. Continuous bare electrode filler wire

Front 22

GMAW Power Source

Back 22

DCEP - Direct Current electrode positive

Front 23

FLUX CORED ARC WELDING (FCAW)

Back 23

A GMAW process that uses the tubular electrode wire with powdered flux inside. Suitable for welding low carbon steel, low alloy, and stainless steel.

Widely used for hardfacing appllications

Front 24

FCAW Advantages

Back 24

1. Deeper penetration

2. Higher deposition rates

3. High deposition efficiency

Front 25

FCAW Disadvantages

Back 25

1. Limited application

2. Only used on ferrous metals, low alloy steels and limited stainless steels

3. Initial cost of equipment high that SMAW

Front 26

METAL CORED ARC WELDING (MCAW)

Back 26

Like FCAW but the metal cored wire has no fluxing ingredients inside but is filled with powdered metal.

Usually iron powder with alloying elements.

Front 27

Advantages of MCAW

Back 27

1. Low smoke and fume levels

2. High deposition efficiency

3. Broad range of alloy choices

4. No Slag

5. Minimal Slag

6. Good Penetration

7. Good bead appearance

Front 28

Safety Req

Electric Shock

Back 28

1. Never permit contact between hot circuit and bare skin.

2. Wear dry, hole free gloves

3. Always insulate yourself from welding circuit

4. Always ensure work lead ground clamp has a good electrical connection

5. Ground work piece to secondary ground to earth

6. Maintain equipment in good working condition

7. Use proper PPE and fall prevention equip

Front 29

Safety Req

Handling of cylinders

Back 29

1. Properly secure cylinder

2. Crack valve to clean threads. Stand to side

3. Adjust pressure slowly to avoid damage to regulators. Stand to one side again.

Front 30

Safety Req

Toxic Gases

Back 30

Main Gases that are toxic

1. Ozone

2. Nitrogen Dioxide

3. Carbon Monoxide

Can be controlled by general ventilation or by proper resp. ppe

Front 31

Safety Req

Toxic Gases - Shielding Gases

Back 31

GMAW and FCAW shielding gas displace oxygen and can cause lung damage or death via suffocation.

Front 32

Safety Req

Protection against Radiation

Back 32

Proper filter lens according to OHS Reg is 10 - 12 depending on current level. (p 210)

Non-reflective, fire retardant clothing.

Front 33

Wire Feed

Push Type

Back 33

Consists of an assembly that pulls wire from the spool and pushes it through the cable assembly to the welding gun.

Usually one unit but can also be from an overhead crane.

Pressure and alignment must be correct to properly work.

Front 34

Wire Feed

Pull Type

Back 34

A smaller but higher speed motor is located in the welding gun to pull filler metal wire through the conduit.

This system makes it possible to increase distance between spool and gun.

Front 35

Pull Type Wire Feed Disadvantages

Back 35

1. Welding gun is heavier and more difficult to use.

2. Rethreading wire more time consuming.

3. Operating life shorter

Front 36

Push-Pull Wire Feed

Back 36

Uses synchronized feed motors to pull wire to the assembly and push it out to the gun.

Advantages are extended distance, faster feed, longer operating life.

Disadvantages are the complexity and cost.

Front 37

Basic Components of a GMAW or FCAW gun

Back 37

1. Contact Tip

2. Shielding Gas Nozzle

3. Shielding Gas Nozzle Insulator

4. Filler Metal Electrode Wire Conduit

5. Shielding Gas Hose

6. Welding Electrode Cable Assembly

7. Welding Gun Trigger

8. Shielding Gas Diffuser

Front 38

Contact Tip

Back 38

Usually made of copper or copper alloy. Conducts welding current and directs work

Must be centered in shielding gas nozzle

Attached via slide or screw

Important to keep clean and clog free

Front 39

Shielding Gas Nozzle

Back 39

Directs an even flowing column of shielding gas to welding zone.

Protect with anti-spatter

Front 40

Air Carbon Arc Cutting

Back 40

Known as CAC-A, AAC. Can cut and gouge all types of ferrous and non ferrous metals quicker than flame cutting.

Can partial cut, gouge, or wash off a surface or prepare joints for welding.

Can remove metal, weld faults, bolts nuts and fasteners.

Front 41

CAC-A (Carbon Arc Cutting)

Principles

Back 41

Works by melting base metal with an electric arc and using jets of air to blow molten metal to form a kerf or groove.

Works by melting and not oxidizing like oxy-fuel.

Can be used on anything that conducts electricity

Front 42

Components of CAC-A

Back 42

1. Welding power source

2. Electrode Holder

3. Compressed air supply system.

Front 43

CAC-A Power

Back 43

Can use AC or DC power

Front 44

Safe Work CAC-A

Ventilation

Back 44

Must ventilate as metals may release toxic fumes when heated.

Must also wear a ventilator when cutting metal that contains chromium

Front 45

Safe Work CAC-A

Noise

Back 45

Noise level from the compressed air is high.

Wear ear plugs or ear muffs

Front 46

Safe Work CAC-A

Radiation

Back 46

Need a standard welding helmet with a darker lens than SMAW. Filter 12-14.

Cover all exposed skin

Front 47

Safe Work CAC-A

Fire

Back 47

Can spray sparks 6 meters away.

Place sheet metal shield.

Have a fire extinguisher or water hose near

Never use oxygen instead of compressed air

Front 48

Electrode Holders

Back 48

Carries welding current to welding electrode.

2 types - twist head type

- jaw type

Need to check for broken parts or insulation to ensure safety and efficiency

Front 49

Ground Clamps

Back 49

Needed to make welding circuit complete. Needs to be checked for good connection otherwise a loss of power may occur.

2 Types - Spring loaded Clamp

- C Clamp

Front 50

Spring Loaded Clamp

Back 50

Most common type.

Advantage is that you can easily change location of connection

Front 51

C-Clamp

Back 51

Allows for a secure connection, preventing arcing on the base metal and ensures a solid electrical connection

Front 52

Electrode Size

Back 52

Measured as the diameter of the inner core wire excluding flux coating.

Sizes: 1/16, 5/64, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 5/16

Front 53

Electrode Type

Fast Fill

Back 53

Deposits substantial amounts of filler material at a fast rate. Used often for production work.

Front 54

Electrode Type

Fast-Freeze

Back 54

Deposits a weld bead with the ability to solidify quickly

Suitable for vertical and overhead position welding

Front 55

Electrode Type

Fill Freeze

Back 55

Deposits thin narrow beads best used for thin metals with shallow penetration

Front 56

Electrode Type

Low Hydrogen

Back 56

Electrodes that contain or lessen hydrogen. Tested by dipping in glycerin.

Front 57

Electrode Coatings

Cellulose

Back 57

Made from wood pulp. Forms a envelope of carbon dioxide and water vapor that excludes oxygen and nitrogen. Sodium or potassium is added to coating to stabilize arc

Front 58

Electrode Coatings

Rutile

Back 58

Another term for titanium dioxide. Makes the arc smooth and stable and forms a hard black slag that gives a smooth finish.

Freq. combined with sodium and potassium

Front 59

Electrode Coatings

China Clay, Silica, Mica

Back 59

Used to provide slag volume and used in controlling viscosity and rate in which slag freezes.

Front 60

Electrode Coatings

Potassium

Back 60

Used as an arc stabilizer and an ionizer.

As ionizer, alters electrical characteristics and helps ease and stabilize flow of current.

Front 61

Electrode Coatings

Ferro-manganese

Back 61

An alloy containing 80 percent manganese. Helps remove oxygen when used as an electrode coating

Front 62

Electrode Classification

Back 62

First letter - designates electric welding

2 numbers - tensile strength in tens of megapascal

3rd number - designates welding positions

4th number - designates composition of coating

Front 63

Electrode Position

Back 63

1. all positions except vertical down

2. flat and horizontal fillet

3. flat position only

4. vertical down

Front 64

Weld joint Design

Lap Joint

Back 64

Two pieces of metal overlap for weld

Front 65

Weld Joint Design

Tee Joint

Back 65

Joins 2 pieces of metal at 90 degrees to each other

Front 66

Weld Joint Design

Corner Joint

Back 66

Also joined at right angles but in an L shape

Front 67

Weld Joint Design

Butt Joint

Back 67

Joins 2 metals lying on the same plane

Front 68

Weld Joint Design

Edge Joint

Back 68

Joins two pieces of metal that are turned up at the edges. Also called a flange joint

Front 69

Tee Joints

Back 69

Allows for maximum access but requires more filler material.

Chances of distortion are high.

Front 70

Corner Joints

Back 70

2 types open and closed

Open - Used more often as full penetration is achieved and results in full strength weld

Front 71

Weld Types

Surfacing Weld

Back 71

Deposits of weld material that are used to build up surface of metal or replace worn metal

Types - Build Up, Buttering, Hardfacing, Cladding

Front 72

Surfacing Weld

Build Up

Back 72

Intended to change dimension such as thickness

Front 73

Surfacing Weld

Buttering

Back 73

Provide a base for another surface weld

Front 74

Surfacing Weld

Hardfacing

Back 74

Intended to create a hard or tough surface to control wear

Front 75

Surfacing Weld

Cladding

Back 75

Create a corrosion or heat resistant layer

Front 76

Weld Types

Tack Welds

Back 76

Short temporary welds used to hold assembly on a short term

Front 77

Weld Types

Fillet Welds

Back 77

Used extensively on lap, tee, and corner joints. Consists of beads that are triangular.

Front 78

Ideal Fillet Weld

Back 78

Joint faces at 90

Face flat or slightly convex

Toes that merge smoothly

Legs of equal length

Front 79

Structural Discontinuities In Weld

Back 79

1. Undercut

2. Incomplete Penetration

3. Underfill

4. Incomplete Fusion

5. Porosity

6. Slag Inclusion

7. Cracking