55) In which of the following forging operations, repeated hammering and closed die are used?

56) In heading operation, to avoid buckling, the length to diameter ratio shall be

57) The process of beveling end of a hole is called

58) In forging operation, scarfing is the method of preparing pieces of metal for

59) The difference between length and breadth of a rectangle is 23m. If its perimeter is 206m, then its area is,