Arc Welding

9.0 ARC WELDING
9.1       Understand Arc welding
9.1.1 Explain the function of arc welding machine.
9.1.2 Recognize the basic components of an arc welding machine.
9.1.3 Name five types of arc welding machines and explain the working principles, advantages and disadvantages of
a. Direct current arc welding machine.
b. Alternating current arc welding machine.
c. Integrated AU/UT arc welding machine.
d. Power driven direct current petrol/diesel arc welding generator.
e. Electric motor driven direct current arc welding generator.
9.1.4 Draw arc welding machine circuits.
9.2       Understand the Polarity of arc welding machine
9.2.1 Define the terminology polarity. Straight polarity and reverse polarity.
9.2.2 Explain the characteristics of polarity.
9.2.3 Explain the procedures to choose the type of polarity.
9.3       Understand Techniques of arc welding.
9.3.1 Sketch and label the parts of an arc.
9.3.2 Explain the effects of arc distance, electrode angle and welding speed in arc welding process.
9.3.3 Explain the method of starting an arc.
9.4       Understand of Electrode
9.4.1 Explain how electrode is produced.
9.4.2 Explain the composition of metals found in the core of the electrode.
9.4.3 Explain the function of electrode coatings.
9.4.4 Explain types, classification, colour and number code of electrodes.
9.5       Understand welding defects
9.5.1 Sketch types welding defect
9.5.2 Explain the reasons welding defect and how to overcome.
9.6       Classify basic types of joints.
9.6.1 Sketch five types of basic joints.
9.6.2 Explain steps taken before preparing welding joint.
9.6.3 Explain the advantages and the uses of every joint.
9.7       Understand distortion
9.7.1 Name types of distortion.
9.7.2 Explain the reasons for distortion and methods of prevention.
9.8       Identify welding terminology.
9.8.1 Explain the welding terminologies such as: bead, throat of weld, leg size, heel penetration, root face and root gape.
9.9       Identify welding symbol.
9.9.1 Describe importance of welding symbols.
9.9.2 Explain types of welding symbols.
9.9.3 Explain the welding symbol characters such as : arrow, reference line, tail end, other side and arrow side.
9.9.4 Interpret welding symbols.