# Mechanical Engineer Interview Questions

#### A CNC vertical milling machine has to cut a straight slot of 10 mm width and 2 mm depth by a cutter of 10 mm diameter between points (0,0) and (100,100) on the XY plane (dimensions in mm). The feed rate used for milling is 50 mm/min. Milling time for the slot (in seconds) is

(A) 120
(B) 170
(C) 180
(D) 240

(B) 170

###### Hint:

Given : width (b) = 10 mm, depth = 2 mm

Distance traveled for cut between points (0,0) and (100,100).
By Pythagoras theorem

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

(A) 0
(B) 2.07
(C) 20.7
(D) 41.4

(D) 41.4

###### Hint:

Since volume of cylinder remains same. Therefore,
Volume before forging = Volume after forging

Percentage change in diameter

#### In a single pass drilling operation, a through hole of 15 mm diameter is to be drilled in a steel plate of 50 mm thickness. Drill spindle speed is 500 rpm, feed is 0.2 mm/rev and drill point angle is 118°. Assuming 2 mm clearance at approach and exit, the total drill time (in seconds) is

(A) 35.1
(B) 32.4
(C) 31.2
(D) 30.1

(A) 35.1

###### Hint:

BC = radius of hole or drill bit (R)
= 15 /2
= 7.5 mm

From ABC,

Travel distance of drill bit
l = thickness of steel plate (t) + clearance at approach + clearance at exit + AB
= 50 mm+ 2 + 2 + 4.506

= 58.506 mm
Feed rate

#### 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

(A) 0.006
(B) 0.031
(C) 0.062
(D) 0.600

(C) 0.062

###### Hint:

t1 = 8 mm, d = 410 mm, r = 205 mm
Reduction of thickness, Dt = 10% of t1

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

(A) increase in coefficient of friction
(B) decrease in coefficient of friction
(D) increase in roll velocity

(A) increase in coefficient of friction

###### Hint:

The main objective in rolling is to decrease the thickness of the metal.
The relation for the rolling is given by

Where,
F = tangential frictional force

𝜇 = Coefficient of friction

𝑃𝑟 = Normal force between the roll and work piece

Now, from the increase in 𝜇, the draft in cold rolling of sheet increases.

#### The crystal structure of austenite is

(A) body centered cubic
(B) face centered cubic
(C) hexagonal closed packed
(D) body centered tetragonal

(B) face centered cubic

###### Hint:

Austenite is a solid solution of carbon in γ -iron. It has F.C.C structure. It has a solid solubility of up to 2% C at 1130°C.

(A) 22°
(B) 26°
(C) 56°
(D) 76°

(B) 26°

#### Machining process                         Mechanism of material removal P. Chemical machining                           1. Erosion Q. Electro-chemical machining              2. Corrosive reaction R. Electro-discharge machining             3. Ion displacement S. Ultrasonic machining                         4. Fusion and vaporization

(A) P-2, Q-3, R-4, S-1
(B) P-2, Q-4, R-3, S-1
(C) P-3, Q-2, R-4, S-1
(D) P-2, Q-3, R-1, S-4

(A) P-2, Q-3, R-4, S-1

# Mechanical Engineering Interview

This articles is all about Mechanical Engineer Interview Questions with solved examples. This part of mechanical Engineering Interview, manufacturing engineering questions are discussed.

#### In abrasive water jet machining, as the distance between the nozzle tip and the work surface increases, the material removal rate

(A) increases continuously

(B) decreases continuously.

(C) decreases, becomes stable and then increases.

(D) increases, becomes stable and then decreases.

(D) increases, becomes stable and then decreases.

###### Hint:

Graph for abrasive jet machining for the distance between the nozzle tip and work surface (l) and abrasive flow rate is given in figure. It is clear from the graph that the material removal rate is first increases because of area of jet increase than becomes stable and then decreases due to decrease in jet velocity.

#### During normalizing process of steel, the specimen is heated

(A) between the upper and lower critical temperature and cooled in still air.

(B) above the upper critical temperature and cooled in furnace.

(C) above the upper critical temperature and cooled in still air.

(D) between the upper and lower critical temperature and cooled in furnace

(C) above the upper critical temperature and cooled in still air.

###### Hint:

Normalizing involves prolonged heating just above the critical temperature to produce globular form of carbine and then cooling in air.

#### The operation in which oil permeated into the pores of a powder metallurgy product known as

(A) mixing

(B) sintering

(C) impregnation

(D) infiltration

(C) impregnation

###### Hint:

If the pores in a sintered compact are filled with an oil, the operation is called as impregnation. The lubricants added to the porous bearings, gears and pump rotors etc.

#### Green sand mold indicates that

(A) polymeric mold has been cured

(B) mold has been totally dried

(C) mold is green in color

(D) mold contains moisture

(D) mold contains moisture

###### Hint:

A green sand mold composed of a mixture of sand (silica sand, SiO2), clay (which acts as binder) and water. The word green associated with the condition of wetness or freshness and because the mould is left in the damp condition, hence the name “green sand mold”.

#### Which one among the following welding processes uses non-consumable electrode ?

(A) Gas metal arc welding

(B) Submerged arc welding

(C) Gas tungsten arc welding

(D) Flux coated arc welding