1.4.1 Furnaces
• Some of the types include,
- coreless induction - magnetic fields induce eddy currents throughout the entire furnace, resulting in melting
- core induction - magnetic fields induce eddy currents in a small section of the furnace, resulting in melting
- gas fired crucible - uses ignited gas and air to heat crucible in enclosed oven
- electric arc - arcs are used to heat metals
- cupolas - layers of metal and ore are placed in this refractory lined vessel, and ignited to produce large volumes of metal.
1.4.2 Inspection of Casting
• General problems with castings are,
- cavities
- projections
- discontinuities
- defective surfaces
- incomplete
- incorrect dimensions
- inclusions
• Typical inspection methods are,
- polishers & microscopes to look at microscopic structures
- metal analyzer to determine chemical composition
- X-rays are used to examine hidden cracks and blowholes