Design of Machine Elements MCQs | Page - 1

 cast iron has more compressive strength.

 in casting metal is in fluid state and hence impossible to control the grain structure.

 cavity is surrounded by sand and hence not good finish is obtained.

 forging is the working of metal in plastic range.

 machining each part is very time consuming.

 generally manufacturing screw is cheaper than driving it.

 with increase of carbon, welding becomes difficult as weld becomes susceptible to cracks.

 tolerances are provided to the parts because variations in the material properties introduce errors and production machines themselves have inherent inaccuracies. another reason to introduce tolerance is that it is not possible to make perfect settings by operator so some tolerances are provided.

 total tolerance is specified on both the sides of the basic dimension. this usually have + and – tolerance of equal amount.

 statistical approach allows wider tolerances compared to complete interchangeability approach. methods used by statistical approach are usually permits cheaper production. mean clearance is equal to (mean size of hole – mean size of shaft).