Question

2)  

If a casting is cooled quickly, we expect the SDAS to?

a) increase b) decrease c) not be affected

A casting process which uses silica grains bonded with clay would be?
a) investment casting b) sand casting c) die casting

A casting process which forces liquid metal into a permanent mold would be?

a) permanent mold casting b) sand casting c) die casting

A casting process which uses a temporary ceramic mold would be?
a) centrifugal casting b) sand casting c) investment casting

To achieve the best properties in a casting, we need?
a) the fastest cooling rate b) sand casting c) a good riser

Which of the following is also a solidification process?

a) riveting b) screwing c) welding

If the tensile test of a material has only a linear elastic portion and no plasticity, it is most likely?

a) metal b) thermoplastic above Tg c) elastomer d) ceramic

Answer 1

1. If a casting is cooled quickly then Secondary Dendrites Arm Spacing will decrease. There will be no time for grain growth due to fast cooling rate so with shorter solidification time SDAS decreases.

2. Sand casting uses Silica grain for better surface finish and uses phenolic resins for proper bonding between Silica grains and clay.

3. Die casting uses permanent mold. It has high production rate but Melting point temperature of the material should be low as the mold is made up of some metal it has its own melting temperature. It gives better surface finish.

4. In investment casting we use temporary ceramic mold. Pattern is made up of wax then slurry and ceramic coating are added around the pattern to produce ceramic shell.

5. If the cooling rate is fast then the grains formed will be fine which will increase the strength of the casting. Sand casting doesn't give good surface finish & riser is used to compensate liquid & solidification shrinkage.

6. Welding is also a solidification process in which weld pool get solidified.

7. Ceramic they are not easily shaped or moulded rest of the material like metal, elastomers and thermoplastics can be moulded, so there will be plastic region in all these materials.