This set of Foundry Question Bank focuses on “Moulding Sand Preparation and Conditioning”.
1. In the following equation, P stands for _________
a) Permeability number
b) Pressure
c) Partial Pressure
d) Partial Fraction
View Answer
Explanation: The equation given above is the standard equation for the measurement of the permeability number. After preparing the test sample of sand, 2000 cm3 of air is passed through the sample and the time taken by it to completely pass through the specimen is noted. Then its permeability is calculated using the above equation.
2. The rate of flow of air passing through a standard specimen under a standard pressure is termed as _____________
a) Green Strength
b) Dry Strength
c) Mould Hardness Number
d) Permeability number
View Answer
Explanation: The standard permeability number test is to measure time taken by a 2000 cm3 of air at a pressure typically of 980 Pa to pass through a standard sand specimen confined in a specimen tube. The standard specimen size is 50.8mm in diameter and length of 50.8 mm.
3. Measurement of strength of molding sands can be carried out on a Universal testing machine.
a) True
b) False
View Answer
Explanation: The measurement of the strength of molding sands can be carried out on the universal sand strength can be measured in compression, shear and tension. The sands that could be tested are green sand dry sand or core sand. The compression and shear test involves the standard cylindrical specimen that was used for the permeability test.
4. Permeability is greatly dependent upon ________________
a) Ramming of sand
b) Sand Particle size
c) Sand grade
d) Moisture content
View Answer
Explanation: The permeability of sand is dependent to a great extent, on the degree of ramming, it is necessary that the specimen be prepared under standard conditions. To get reproducible ramming conditions, a laboratory sand rammer is used along with a specimen.
5. Green shear strength is more than the Green compression strength.
a) True
b) False
View Answer
Explanation: The Green compression strength that was used is generally in the range of 30 to 160 kPa and the Green shear strength can vary from 10 to 50 kPa according to the standards of the sands.
6. The strength of the sand ____________ on drying.
a) Remains same
b) Increases
c) Decreases
d) Depends on the sand
View Answer
Explanation: The tests are carried out with the standard specimen dried between 105 and 110 C for 2 Hours. Since the strength increases greatly with drying, it may be necessary to apply larger stresses than the other similar tests.
7. The mould hardness measuring test is similar to _________
a) Brinells Hardness test
b) Vikers hardness test
c) Rockwell Hardness test
d) Sand Grain analysis
View Answer
Explanation: In a foundry, the mould hardness is measured by a method similar to Brinell hardness test. A spring loaded steel ball with a mass of 0.9 kg is indented into the standard sand specimen prepared. The depth of the indentation can be directly measured on the scale.
8. Which of the following binder immediately increases the binding properties?
a) Cereal binder
b) Clay
c) Pitch
d) Silica
View Answer
Explanation: The Cereal binder when added to the molding sand increases the binding properties by 2% as soon as it is added. It has excellent mixing properties and the wide availability increases its probability of being used.
9. The iron oxide reduced the hot strength.
a) True
b) False
View Answer
Explanation: Iron oxide is used approximately in the amount of 3% in the moulding sand. It is used to improve the surface finish, decrease metal penetration and reduces the burn-on. Hence, it decreases the green strength and permeability while improving the hot strength.
10. Molasses enhances the bench life of the sand and is the best sand conditioner.
a) True
b) False
View Answer
Explanation: The molasses is the organic product got from the sugar industry. This organic binding material is used with the mould and core sand. They increase the resistance to deformation and improve bench life.
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