Metal Casting Practice Questions for GATE Mechanical Engineering.
A flat plate is to be cast in an open mold whose bottom has a square shape that is 200 mm × 200 mm. The mold is 40 mm deep. A total of 1,000,000 mm3 of molten aluminum is poured into the mold. Solidification shrinkage is known to be 6.0%. The linear shrinkage due to thermal contraction after solidification to be 1.3%. If the availability of molten metal in the mold allows the spure shape of the cast plate to maintain its 200 mm × 200 mm dimensions until solidification is completed, determine the final dimensions of the plate.
A 196 mm x 196 mm x 25 mm
B 197.40 mm x 197.40 mm x 23.195 mm
C 190 mm x 189 mm x 24 mm
D 203 mm x 203 mm x 23.5 mm
In the casting of steel under mold conditions, the mold constant in Chvorinov’s rule is known to be 4.0 min/cm2, based on previous experience. The casting is a flat whose length = 35 cm, width = 10 cm, and thickness = 15 mm. Determine how long it will take for the casting to solidify.
A 9.78 min
B 10 min
C 9 min
D 8.45 min
In casting experiments performed using a certain alloy and type of sand mold, it took 155 s for a cube – shaped casting to solidify. The cube was 50 mm on a side. Determine the value of the mold constant in Chvorinov’s rule.
(1) 2.322 s/mm2
(2) 2.5 s/mm2
(3) 3.12 s/mm2
(4) 3 s/mm2
In casting experiments performed using a certain alloy and type of sand mold, it took 155 s for a cube – shaped casting to solidify. The cube was 50 mm on a side. If the same alloy and mold type were used, find the total solidification time for a cylindrical casting in which the diameter = 30 mm and length = 50 mm.
A 1 min
B 1.24 min
C 1.45 min
D 1.56 min
A cylindrical riser is to be used for a sand – casting mold. For a given cylinder volume, determine the diameter – to – length ratio that will maximize the time to solidify.
A 42.0 mm thick plate made of low carbon steel is to be reduced to 34.0 mm in one pass in a rolling operation. As the thickness is reduced, the plate widens by 4%. The yield strength is 290 MPa. The entrance speed of the plate is 15.0 m/min. The roll radius is 325 mm and the rotational speed is 49.0 rev/min. Determine (a) the minimum required coefficient of friction that would make this rolling operation possible, (b) exit velocity of the plate, and (c) forward slip.
A (a) 0.124 (b) 15 m/min (c) 0.056
B (a) 0.157 (b) 17.8 m/min (c) -0.056
C (a) 0.24 (b) 16 m/min (c) -0.067
D (a) 0.34 (b) 14 m/min (c) 0.065
A series of cold rolling operations are to be used to reduce the thickness of a plate from 50 mm down to 25 mm in a reversing two – high mill. Roll diameter = 700 mm and coefficient of friction between rolls and work = 0.15. The specification is that the draft is to be equal on each pass. Determine (a) minimum number of passes required, and (b) draft for each pass?
A 4 passes, 6.25 mm
B 3 passes, 6 mm
C 4.5 passes, 7 mm
D 5 passes, 9.4 mm
A plate that is 250 mm wide and 25 mm thick is to be reduced in a single pass in two – high rolling mill to a thickness of 20 mm. The roll has a radius = 500 mm, and its speed = 30m/min. The work material has a strength coefficient = 240 MPa and a strain – hardening exponent = 0.2. Determine (a) roll force, (b) roll torque, and (c) power required to accomplish this operation.
A (a) 1850 kW (b) 46 kN-m (c) 92 kW
B (a) 1851.829 kN (b) 46.296 kN-m (c) 92.591 kW
C (a) 1860.213 kW (b) 47.98 kN-m (c) 90 kW
D (a) 1849.987 kN (b) 46.686 kN-m (c) 93.876 kW
The cutting force and thrust force in an orthogonal cutting operation are 1470 N and 1589 N, respectively. The rake angle = 50o, the width of the cut = 5.0 mm, the chip thickness before the cut = 0.5, and the chip thickness ratio = 0.38. Determine (a) the shear strength of the work material and (b) the coefficient of friction in the operation.
A (a) 95 MPa (b) 1.15
B (a) 89 MPa (b) 0.87
C (a) 80 MPa (b) 1.15
D (a) 95.9 MPa (b) 1.291
In a production turning operation, the foreman has decreed that a single pass must be completed on the cylindrical workpiece in 5.0 min. The piece is 400 mm long and 150 mm in diameter. Using a feed = 0.30 mm/rev and a depth of cut = 4.0 mm, what cutting speed must be used to meet this machining time requirement?
A 125.7 m/min
B 128 m/min
C 130.8 m/min
D 111.87 m/min