This set of Foundry Interview Questions and Answers for freshers focuses on “Methods of Making Cores”.
1. Core sand can be rammed in a dump type core box on a ______________
a) Jolt Machine
b) Sand Slinger
c) Core roll over machine
d) Core extrusion machine
View Answer
Explanation: In a jolting machine, the core box filled with sand is mounted on a jolt table which is raised to a certain height and then dropped under on its own weight. Sand gets rammed due to this sudden fall.
2. ____________ machine is similar to the mold roll over machine.
a) Core blowing machine
b) Squeezing machine
c) Core roll over machine
d) Core extrusion machine
View Answer
Explanation: The core roll over machine is similar to the mold roll over machine. Core box is rammed with the sand using the jolt principle. Core box is then rolled over, the core is withdrawn. After this, the core box is sent to the baking oven.
3. Sand Slinger is used for filling and ramming a large core.
a) True
b) False
View Answer
Explanation: Sand Slinger makes use of a high speed rotating sand impeller which throws the sand in the core box at high velocities. The impact action of the sand stream is responsible for the compacting (or ramming) the core.
4. Cores of which of the following shapes are not produced in core extrusion process:
a) Square
b) Hexagonal
c) Round
d) Random
View Answer
Explanation: In a core extrusion machine, a die is to be made and fixed at one end. The machine has a hopper through which the core sand is fed to a horizontal spiral conveyor. The cores of basic geometrical shape are only produced in this method.
5. Simple cores of regular shapes and uniform cross-section can be extruded easily on a core extrusion process.
a) True
b) False
View Answer
Explanation: In a core extrusion machine, the spiral conveyor present is rotated and it forces the core sand through a die of specified shape only. Hence only simple cores of regular shapes and uniform cross section can be extruded from this process.
6. Core boxes to be used on the core blowing machines are made up of ______________
a) Iron
b) Brass
c) Aluminum
d) Carbon
View Answer
Explanation: The cores produced in the core blowing machines are produced due to the air at high velocity. It is important that the air has to be let out through the vents. The method of forming vents is easily done in aluminum. Hence the core boxes are made up of aluminum.
7. The core boxes are provided with wires perform a function of which of the following component?
a) Riser
b) Gates
c) Vents
d) Shell
View Answer
Explanation: The incoming air in the core blowing machine with the sand is exhausted through the vents provided in the core-box. The wires in the core boxes automatically provide vent holes in the cores as they are blown off. They are withdrawn before the core is stripped.
8. The sand carrying the compressed air stream in the core blowing machine is responsible for filling the core box and ramming the core.
a) True
b) False
View Answer
Explanation: Core blowing machine makes use of compressed air (at 5 to 7 kg/cm² pressure) to blow the sand into the core box at high velocity. Thus, the filling and ramming of the core are done.
9. In the Shell Core making, when the sand blowing is employed, it is preferred to use resin precoated sands to avoid resin segregation.
a) True
b) False
View Answer
Explanation: In shell core making, the sand is mixed with about 2% to 5% thermosetting resin of phenolic type is either dumped or blown and then when the sand blowing is carried out, resin precoated sand is preferred to impart high permeability and smooth surfaces.
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