Some of the important cold drawing processes are as follows:
� Bar and Rod Drawing: In the case of bar drawing the hot drawn bars are at first pickled, washed and coated to prevent oxidation. Once this is done a draw bench is used for the process of cold drawing. In order to make an end possible to enter a drawing die the diameter of the rod is reduced by the swaging operation. This end is fastened by chains to the draw bench and the end is gripped by the jaws of the carriage. In this method a high surface finish and accuracy dimensionally is obtained. The products of this process can be used directly without any further machining.
� Wire Drawing: Similar to the above process the bars are first pickled, washed and coated to prevent any oxidation. After this the rods are passed through several dies of decreasing diameter to provide a desired reduction in the size ( diameter ). The dies used for the reduction process is generally made up of carbide materials.
� Tube Drawing: This type of drawing is very similar to the bar drawing process and in majority of cases it is accomplished by the use of a draw bench.
2. What are the different theories of failure under static load, explain briefly?
The main theories of failure of a member subjected to bi-axial stress are as follows:
� Maximum principal stress theory ( Rankine�s theory): This theory states that failure occurs at a point in member where the maximum principal or normal stress in a bi-axial system reaches the maximum strength in a simple tension test.
� Maximum shear stress theory ( Guest�s or Tresca�s theory): This theory states that failure occurs when the biaxial stress reaches a value equal to the shear stress at yield point in a simple tension test.
� Maximum principal strain theory ( Saint Venant theory): This theory states that failure occurs when bi-axial stress reaches the limiting value of strain.
� Maximum strain energy theory ( Haigh�s theory): This theory states that failure occurs when strain energy per unit volume of the stress system reaches the limiting strain energy point.
� Maximum distortion energy theory ( Hencky and Von Mises theory): This theory states that failure occurs when strain energy per unit volume reaches the limiting distortion energy.
3. What happens if gasoline is used in a Diesel engine? Diesel engine will work ?
No, It will not work, as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine is 15 to 22. Thus on such high compression, gasoline gets highly compressed & it may blast.
4. Which Mechanism is used in Automobile gearing system.
Differential mechanism.
5. Why different types of sound are produced in different bikes though they say run on SI engine.
Engine specifications are different in different manufactures like as Bore Diameter(CC), Ignition timing. Also the exhaust passage take more responsible for sound.
6. Why entropy decreases with the increase in temperature?
Ds = dQ/T Entropy is inversely proportional to the temperature so. as temp. Increases, entropy decreases.
7. How to calculate bearing number to diameter of the inner and outer.
Divide the shaft diameter size by 5, It will give last two digitof the bearing no. and according to type of load we have to choose the type of bearing and that will give prior no. of the bearing.
8. Explain Bicycle rear wheel Sprocket working?
Rear wheel sprocket works under the principle of ratchet and pawl.
9. Definition of Octane number & Cetane number
� Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octane and h-heptane. It is the measure of rating of SI engine.
� Cetane No.- Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.
10. What are the points that should be kept in mind during forging design?
Some of the points that should be followed while forging design are:
� A radial flow of grains or fibers must be achieved in the forged components.
� The forged items such as drop and press forgings should have a parting line that should divide the forging into two equal halves.
� The ribs in a forging should not be high or thin.
� In order to avoid increased die wear the pockets and recesses in forgings should be minimum.
� In forgings the parting line of it should lie as far as possible in a single plane.
� For ease of forging and easy removal of forgings the surfaces of the metal should contain sufficient drafts.
Part 1 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
Part 2 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
Part 3 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
Part 4 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
Part 5 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
Part 6 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
Part 8 | Top 10 Basic Mechanical Engineering Interview Questions and Answer
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