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Casting by Mind Map: Casting

1. cast ability

2. lost wax technique

3. sprue

3.1. types

3.2. single sprue

3.3. multiple sprue

4. steps of casting

4.1. formation of wax pattern

4.1.1. indirect

4.1.2. direct

4.2. spruing of wax pattern

4.2.1. a channel through which molten alloy can reach mould after the wax has been eliminated

4.3. investing of wax pattern

4.3.1. process by which sprued wax pattern is embedded in material called an investment

4.4. burn out wax pattern

5. Equation to make a casting fit

5.1. wax shrinkage + gold/metal shrinkage = setting expansion +hygroscopic expansion+ thermal expansion of investment material+ wax expansion

5.1.1. Shrinkage Wax shrinkage alloy shrinkage

5.1.2. Expansion water immersion technique low heat hygroscopic expansion

6. Faults in casting

6.1. Finning and bubbling

6.1.1. Investment material heated up too rapidly forming cracks REASONS prolonged heating heating rate too rapid water/powder ratio excessive casting pressure cooling of the investment material prior to casting

6.2. incomplete casting

6.2.1. Reasons

6.2.2. location and number of sprues

6.2.3. alloy not properly melted

6.2.4. incomplete wax elimination

6.2.5. shortage of alloy reservoir

6.2.6. incomplete filling of mould cavity

6.3. porosity in casting

6.4. oversized and undersized casting

7. Under or oversize casting

7.1. burnout temperatures

7.2. immersion line

7.3. water added technique

7.4. water bath temperature

7.4.1. decrease hygroscopic expansion

8. General problems

8.1. short rounded margins

8.2. miscasting

9. Casting machines and method of melting

9.1. alloy may be melted in mould sprue base or in a separate crucible

9.2. alloy maybe melted by gas-air , electrical induction heating