Materials Science and Manufacturing Engineering Miscellaneous
- Wall thickness of drawn cup is controlled by
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It is clearance between punch & die in subsequent reduction in single stroke.
Correct Option: D
It is clearance between punch & die in subsequent reduction in single stroke.
Direction: In a multi-pass operation, a round bar of 10 mm diameter and 100 mm length is reduced in crosssection by drawing it successively through a series of seven dies of decreasing exit diameter. During each of these drawing operations, the reduction in crosssection area is 35%. The yield strength of the material is 200 MPa. Ignore strain hardening.
- Neglecting friction and redundant work, the force (in KN) required for drawing the bar though the first die, is
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Fd = K ln (R) σ Af
π × d²f1 = 0.65 π ×(10)² 4 4
Fd = 4.39 KNCorrect Option: D
Fd = K ln (R) σ Af
π × d²f1 = 0.65 π ×(10)² 4 4
Fd = 4.39 KN
- The total true strain applied and the final length (in mm), respectively are
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Di = 10 mm li = 100 mm n = 7
True Strain ∈ = ln 
di 
² df Af = (0.67)7 × π (10)² 4
df = 2.21 mm∈ = 2 ln 10 ² 2.21
∈ = 3.02
Constancy of volumeπ di²li = π df²lf 4 4
lf = 2047.46 mmCorrect Option: C
Di = 10 mm li = 100 mm n = 7
True Strain ∈ = ln di ² df Af = (0.67)7 × π (10)² 4
df = 2.21 mm∈ = 2 ln 10 ² 2.21
∈ = 3.02
Constancy of volumeπ di²li = π df²lf 4 4
lf = 2047.46 mm
- Using direct extrusion process, a round billet of 100 mm length and 50 mm diameter is extruded. Considering an ideal deformation process (no friction and no redundant work) extrusion ratio 4 and average flow stress of material 300 MPa, the pressure (MPa) on the ram will be
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A, L0 = 100,
σy = 300 MPa
d0 = 50 mmE.R. = A0 = 4, A0 = 1962.5 mm² A1 
Extrusion pressure = 300 in (extrusion ratio) = 415.8 MPaCorrect Option: A
A, L0 = 100,
σy = 300 MPa
d0 = 50 mmE.R. = A0 = 4, A0 = 1962.5 mm² A1
Extrusion pressure = 300 in (extrusion ratio) = 415.8 MPa
Direction: A 10 mm diameter annealed steel wire is drawn through a die at a speed of 0.5 m/s to reduce the diameter by 20%. The yield stress of the material is 800 MPa.
- The power required for the drawing process (in kW) is
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P = Fd × V =357 × π × (8)² × 0.5 4
P = 8.972 KwCorrect Option: A
P = Fd × V =357 × π × (8)² × 0.5 4
P = 8.972 Kw
