This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Molding Processes”.
1. Which of the following is the principal material used for Nobake moulding process?
a) Furan or Urethane
b) Wood saw
d) Water only
Explanation: Nobake is a moulding process that involves the use of furan (chemical binders) to bond the moulding sand.
2. In Nobake moulding process, the chemical process of hardening of binder starts when ___________
a) The sand is poured into the mixture
b) The sand is taken out of the mixture
c) The mixture is poured into the moulding flask
d) When the molten metal is poured into the cavity
Explanation: A mixture is used to blend the sand with chemical binder. The chemical hardening starts when this sand exits the mixture.
3. The Nobake mould have a higher strength as compared to other moulds due to _________
a) Its higher moisture content
b) Its lower moisture content
c) The property to withstand higher metallostatic pressures during casting
d) The property to adapt to any volume
Explanation: The Nobake moulding process provides a good strength of mould, hence, it can withstand the metallostatic pressures and can give good dimensional tolerances.
4. Which of the following statement is true?
a) It is possible to pour only ferrous metals for casting in Nobake process
b) It is possible to pour only non-ferrous metals for casting in Nobake process
c) Both ferrous as well as non ferrous metals can be used for casting through Nobake process
d) Neither ferrous, nor non-ferrous metals are used for casting in nobake process
Explanation: Both ferrous as well as non-ferrous metals are compatible with mould made though Nobake process.
5. The degree or intensity of ramming _________
a) Increases bulk density
b) Decreases bulk density
c) Does not change bulk density
d) Can increase as well as decrease bulk density
Explanation: The increased degree of ramming results in an increase of bulk density or hardness of sand.
6. Permeability of green sand ________
a) Increases with ramming
b) Decreases with ramming
c) Can increase and decrease as well with the amount of ramming
d) Does not alter with ramming
Explanation: The permeability of green sand decreases with an intensity of ramming done on the sand. Hence, the amount of clay is adjusted to keep permeability in a profitable zone.
7. Natural moulding sand have which of the following quality(/ies) __________
a) Freely available in abundance
b) Contains clay in a large amount
c) Moisture content range is wider
d) All of the mentioned
Explanation: Natural moulding sand is cheap, easily available and has a proper consistency of moisture and clay. Hence, requires less time for preparation.
8. R.P.M stands for which of the following moulding process?
a) Rotor Plastic Moulding
b) Raisin Pit Moulding
c) Rubber Plaster Moulding
d) Rough Print Moulding
Explanation: R.P.M stands for Rubber Plaster Moulding. RPM is also known as plaster moulding, since, use of plaster of paris is done in this process.
9. RPM is only used for castings of which of the following material?
a) Ferrous metals
b) Non-ferrous Metals
Explanation: Rubber Plaster Moulding process is used for making mould that can only be used for producing non-ferrous castings like copper and aluminum based alloys.
10. What is the range of temperature used for baking molds using plaster moulding process?
Explanation: The preset mould is ignited to burn off the volatile content in the set gel to a temperature range of 120°-260°.
11. The baking process in plaster moulding process induces which of the following defects?
a) It depletes down the content of water at a very scarce level
b) It develops microscopic cracks onto the surface of mould
c) It gives the surface improper heat that causes differential heat treatment while casting solidification
d) The Calcium reacts at elevated temperatures used for baking the mould
Explanation: The baking of mould in plaster moulding process causes the development of microscopic cracks, which results in improper surface of casting.
12. The dried plaster mould have __________
a) Low permeability
b) High permeability
c) Moderate permeability
d) Same amount of permeability as other moulds
Explanation: The dried plaster moulds have extremely low permeability, about- 1 to 2 AFS.
13. Pit moulding is used for _________
a) Low weighting castings
b) Moderate weighting castings
c) Heavy weighting castings
d) Making castings that requires less time to process
Explanation: Very heavy castings can be made out using pit moulding process. Castings weighing up to 150 tons can be processed through pit moulding.
14. Which of the following is a principle binder used in carbon dioxide moulding?
b) Carbon Dioxide
d) Sodium silicate
Explanation: Sodium silicate is the principle binder used in carbon dioxide moulding process. The mixture of sodium silicate and sand is treated with carbon dioxide to form a bond.
15. Which of the following compound forms the bond between sand particles in carbon dioxide moulding process.
b) Amorphous silica
c) Dehydrated water
d) Carbon Monoxide
Explanation: Amorphous silica forms the bond between sand particles. It is produced by reaction or treatment of mixture of sand and sodium silicates by carbon dioxide.
Sanfoundry Global Education & Learning Series – Casting, Forming and Welding.
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