WELDING WELDING EQUIPMENTEQUIPMENT

WELDING WELDING EQUIPMENTEQUIPMENT

BRAZING BRAZING BRAZING BRAZING GAS FUSION GAS FUSION

WELDINGWELDING

GAS FUSION GAS FUSION WELDINGWELDING

ELECTRIC ELECTRIC ARC ARC

WELDINGWELDING

ELECTRIC ELECTRIC ARC ARC

WELDINGWELDING

INDUSTRIAL INDUSTRIAL TECHNOLOGY-METALTECHNOLOGY-METALASSOCIATED THEORYASSOCIATED THEORY

TOPICTOPIC 5.5.

WELDING & BRAZINGWELDING & BRAZING

SAFETY SAFETY PRECAUTIONSPRECAUTIONS

SAFETY SAFETY PRECAUTIONSPRECAUTIONS

WELDING & WELDING & BRAZING BRAZING

BLOWPIPEBLOWPIPE

WELDING & WELDING & BRAZING BRAZING

BLOWPIPEBLOWPIPE

WELDING EQUIPMENTWELDING EQUIPMENTAfter steel components have been cut and shaped they can be joined together. This is known as fabrication. It may be achieved by using mechanical fasteners, such as bolts & rivets, or the parts may be joined together by various soldering and welding methods. All of these processes involve heating the metals to be joined, the varying, according to the particular process. The heat may be applied by the burning of or by using

Compressed gases are kept in strong steel–walled They are rented from gas companies, who are responsible for and the cylinders on a regular basis to guarantee their safety.

temperature

gaseselectricity.

cylinders.

filling testing

GAS WELDING EQUIPMENT

Spark arrestor

This safety device is fitted between the hose and the blowpipe.

SAFETY PRECAUTIONSSAFETY PRECAUTIONSThe cylinders are available in several sizes, e.g., , and each cylinder is colour coded to indicate the type of gas they contain. The threads on fuel gas fittings are handed and the threads on non-fuel gas fittings are handed.

E or D

leftright

What precautions should be taken with cylinders?

 What particular precautions should be taken with oxygen cylinders?

 

What particular precautions should be taken with acetylene cylinders?

Cylinder taps should only be turned on

  turn to enable them to be turned off quickly in an emergency. Hoses and fittings should be checked  regularly for and wear & tear.

Cylinders should be chained upright. Valves must be closed when not in use.

Keep oil away from oxygen fittings.

Acetylene bottles must remain upright.

one full

damage

Pressure gauge

Contents gauge

Adjusting knob

Hose connection

Cylinder connection

WELDING & BRAZING WELDING & BRAZING BLOWPIPEBLOWPIPE

Tip Mixing chamber Fuel valve Oxygen valve

Handle

Lighting the Blowpipe

1. Point the tip upwards and away from flammable objects.

2. Turn on the fuel and light with a flint.

3. Slowly open the oxygen valve and adjust to a neutral flame.

ALWAYS WEAR GOGGLES WHEN USING THE BLOWPIPEALWAYS WEAR GOGGLES WHEN USING THE BLOWPIPE

CARBURISING FLAME

OXIDISING FLAME

NEUTRAL FLAMEfeather

Small cone

BRAZINGBRAZINGBrazing (also known as bronze welding) is a non fusion welding process. This is because the parent metals do not melt, only the metal.

 Brazing is a popular method of joining metals, and thin metals. It does not require as much heat as welding.

 Describe the preparation needed to make a successful brazed joint.

filler

dissimilar

1. Shape the parts to be brazed so they are a good “fit”.

2. Clean the metal in the vicinity of the join with abrasive cloth.

3. Apply a suitable flux where the filler is to be applied.

Clear goggles are suitable when brazing.

What is the filler rod used for brazing, at what temperature does it melt, and how does it work.

 

How do you know when the parent metal is hot enough to apply the filler rod?

 

 

What purpose does the flux perform?

 

Tobin bronze melts above 5500 and flows into the grain boundaries of the parent metal.

When it is dull red it will melt the bronze as it is touched to the joint.

It cleans the metal and prevents further corrosion.

GAS FUSION WELDINGGAS FUSION WELDING

Gas fusion welding requires temperatures than

brazing because the parent metal melts as well as the filler metal. For this reason oxy-acetylene equipment is used. The parent metal and the metal must be the  composition.

What type of eye protection should be used when gas fusion welding?

 

higher

fillersame

Approved shaded welding goggles protect the eyes against sparks, heat and bright light.

1. Point the tip upwards and away from flammable objects.

2. Turn on the fuel and light with a flint.

3. Slowly open the oxygen valve and adjust to a neutral flame.

Describe the procedure for lighting the oxy-acetylene torch.

Oxygen Acetylene

50kPa 50kPa

GAS FUSION WELDINGGAS FUSION WELDING

GAS WELDING A BUTT JOINGAS WELDING A BUTT JOIN

blowpipe

Filler rod

ELECTRIC ARC WELDINGELECTRIC ARC WELDINGThis type of welding uses electricity to melt the parent metal and a filler metal. A transformer converts the mains power supply by

the voltage, and

the amperage.

decreasing

increasing

SAFETYSAFETY

1.1. Use a full-faced helmet with Use a full-faced helmet with the correct shaded lens.the correct shaded lens.

2.2. Cover unprotected skin to Cover unprotected skin to avoid burn from ultraviolet avoid burn from ultraviolet rays.rays.

3.3. Avoid welding in damp Avoid welding in damp conditions.conditions.

4.4. Shield your work from other Shield your work from other workers, children and pets.workers, children and pets.

transformer

+ive

-ive

What function does the flux coating on the welding electrode/rod perform?

It prevents oxidisation of the metal during the welding process.

ELECTRIC ARC WELDINGELECTRIC ARC WELDING

DOWN-HANDDOWN-HAND ARC WELDING ARC WELDING THE FOUR MAIN VARIABLES TO THE FOUR MAIN VARIABLES TO A SUCCESSFUL WELDA SUCCESSFUL WELD

1. The Amperage. In general, the higher the amperage the higher the temperature.

2. Angle of Rod. This will influence the depth of penetration and the effective strength.

3. Speed of Traverse. If the rod is moved too quickly the parent metal will not melt sufficiently.

4. Length of the Arc. A shorter arc produces a neater, penetrating weld with minimal distortion.

Core wireGaseous shield

slag

Flux coating

Arc stream

Molten pool

200-300

Tack weld

Tack weld

electrode

CROSS-SECTIONAL VIEWCROSS-SECTIONAL VIEW

PICTORIAL VIEWPICTORIAL VIEW