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Design and Manufacture 2 > Welding > Flashcards

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
thermal conductivity
mechanical properties of the material


How ifs friction linear heat welding done

Frictional heat is made through rubbing two surfaces, with a third it it is needed to be joined.
Contact pressure causes frictional heating and raises the temperature
Components don't need to be circular or tubular