GATE Questions & Answers of Load Estimation for Bulk (Forging, Rolling, Extrusion, Drawing)

What is the Weightage of Load Estimation for Bulk (Forging, Rolling, Extrusion, Drawing) in GATE Exam?

Total 18 Questions have been asked from Load Estimation for Bulk (Forging, Rolling, Extrusion, Drawing) topic of Casting, Forming and Joining Processes subject in previous GATE papers. Average marks 1.67.

The maximum reduction in cross-sectional area per pass ( $R$ ) of a cold wire drawing process is

                                                   $ R=1\;-e^{-\left(n+1\right)} $,

where $n$ represents the strain hardening coefficient. For the case of a perfectly plastic material, $R$ is

The percentage scrap in a sheet metal blanking operation of a continuous strip of sheet metal as shown in the figure is _______ (correct to two decimal places).

 

Match the following products with the suitable manufacturing process

 Product  Manufacturing Process
P Toothpaste tube 1 Centrifugal casting
Q Metallic pipes 2 Blow moulding
R Plastic bottles 3 Rolling
S Threaded bolts 4 Impact extrusion

 

A steel wire is drawn from an initial diameter $ \left(d_i\right) $ of 10 mm to a final diameter $ \left(d_f\right) $ of 7.5 mm. The half cone angle $ (\alpha) $ of the die is $ 5^\circ $ and the coefficient of friction $ \left(\mu\right) $ between the die and the wire is 0.1. The average of the initial and final yield stress $ \left[{\left(\sigma_Y\right)}_{avg}\right] $ is 350 MPa. The equation for drawing stress $ \sigma_f $ , (in MPa) is given as:

                              $ \sigma_f={\left(\sigma_Y\right)}_{avg}\left\{1+\frac1{\mu\;cot\alpha}\right\}\left[1-\left(\frac{d_f}{d_i}\right)^{2\mu\;cot\alpha}\right] $

The drawing stress (in MPa) required to carry out this operation is _________ (correct to two decimal places).

A 10 mm deep cylindrical cup with diameter of 15 mm is drawn from a circular blank. Neglecting the variation in the sheet thickness, the diameter (upto 2 decimal points accuracy) of the blank is _________ mm.

It is desired to make a product having T-shaped cross-section from a rectangular aluminium block. Which one of the following process is expected to provide the highest strength of the product?

A rod of length 20 mm is stretched to make a rod of length 40 mm. Subsequently, it is compressed to make a rod of final length 10 mm. Consider the longitudinal tensile strain as positive and compressive strain as negative. The total true longitudinal strain in the rod is

In a slab rolling operation, the maximum thickness reduction $\left(\triangle h_{max}\right)$ is given by $\triangle h_{max}=\mu^2R$, where R is the radius of the roll and μ is the coefficient of friction between the roll and the sheet. If μ = 0.1 , the maximum angle subtended by the deformation zone at the centre of the roll (bit angle in degrees) is________.

In a two stage wire drawing operation, the fractional reduction (ratio of change in cross sectional area to initial cross sectional area) in the first stage is 0.4. The fractional reduction in the second stage is 0.3. The overall fractional reduction is

The flow stress (in MPa) of a material is given by

σ=500ε0.1,

Where ε is true strain. The Young’s modulus of elasticity of the material is 200 GPa. A block of thickness 100 mm made of this material is compressed to 95 mm thickness and then the load is removed. The final dimension of the block (in mm) is ____

In a rolling operation using rolls of diameter 500 mm, if a 25 mm thick plate cannot be reduced to less than 20 mm in one pass, the coefficient of friction between the roll and the plate is__________

In a rolling process, the maximum possible draft, defined as the difference between the initial and the final thickness of the metal sheet, mainly depends on which pair of the following parameters?

P: Strain
Q: Strength of the work material
R: Roll diameter
S: Roll velocity
T: Coefficient of friction between roll and work

In a rolling process, the state of stress of the material undergoing deformation is

A solid cylinder of diameter 100 mm and height 50 mm is forged between two frictionless flat dies to a height of 25 mm. The percentage change in diameter is

In a single pass rolling process using 410 mm diameter steel rollers, a strip of width 140 mm and thickness 8 mm undergoes 10% reduction of thickness. The angle of bite in radians is

The maximum possible draft in cold rolling of sheet increases with the

In a single pass rolling operation, a 20 mm thick plate with plate width of 100 mm, is reduced to 18 mm. The roller radius is 250 mm and rotational speed is 10 rpm. The average flow stress for the plate material is 300 MPa. The power required for the rolling operation in kW is closest to

In open – die forging, a disc of diameter 200 mm and height 60 mm is compressed without any barreling effect. The final diameter of the disc is 400 mm. The true strain is