Flashcards in Welding Deck (10):
What is welding?
Joining process of two or more components. Using heat or pressure to coalesce the components.
Welding can be through fusion or solid states.
Filler is used to replace material lost through melting.
Needs a skilled labourer but it is hazardous and material defects can be hard to detect
Describe two types of fusion welding
Oxyfuel welding burns a mixture of oxygen anf fuel to locally melt the material.
Arc welding is when the heat is achieved using an electric arc, a filler is usually used
Describe three types of solid state welding which do not use fillers
Resistance welding creates heat using a current that passes through workpieces held together by pressure
Friction welding coalesces parts using heat of friction
Ultrasonic welding uses moderate pressure and motion at ultrasonic frequencies
Faults in fusion welds
Distortion, warping and dicolouration of components is common
Cracks form: transverse, longitudinal, underbead and toe
Other faults include incomplete fusion, undercut, underfill and overlap
Describe resistance spot welding
Pressure is applied and heat is generated using a high current between the welded surfaces
it is used on sheet metal
no need for shield gas, flux or filler
How is resistant welding done?
Its used in mass production of cars.
welds are between 5-10mm diameters
electrodes made from copper alloys or tungsten
joint isnt airtight
What is resistant seam welding
Electrodes are rotating wheels
Airtight deal are produced
Uniform curves and straight line seams are made
Used on fuel tanks
How is resistant seam welding carried out
Heat is generated through friction at the interface of two components being joined.
Rotating member is clamped securely to the chuck to resist torque and axial forces without slipping
What does the weld zone depend on?
Amount of heat generated
mechanical properties of the material