Mechanical Engineering Interview Questions and answers - Design, Safety and Maintenance

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Top 50 + Mechanical Engineering Interview Questions and answers for freshers on design, safety and maintenance.

1)  What safety precautions should be observed while working in the workshop ?

1) Keep shop floor clean, free from oil and other slippery materials.
2) Wear proper dress and avoid loose clothing and loose hair.
3) Wear shoes and avoid chapels.
4) Avoid playing, loose talk and funning inside the shop floor.
5) Keep good housekeeping and put all unnecessary items and rejected items in scrap box.
6) Learn everything about the machine before starting and clear all the doubts.
7) Keep a safe distance from rotating and sliding parts.
8) Never store inflammable materials inside or around the shop.
9) Never play with electricity, fire, parts with sharp edge etc.
10) Keep fire buckets and extinguishers ready for use.

2)  What are the precautions to be taken to avoid fire ?

1) The buckets along with sand should be placed inside the workshop.
2) Switches and other electrical parts must be made of fireproof material.
3) Carbon dioxide gas should be place at required points in special containers.
4) Fire extinguishers of suitable type should be placed at accessible places.

3)  What are the methods of extinguishing fire ?

1) Starvation. Separating or removing the burning material from the neighbour hood of the fire.
2) Blanketing. Preventing the air flow to the fire.
3) Cooling. Lowering the heat created by burning materials.

4) What is a Drawing ?

It is a graphical representation of a real thing to define and specify the shape and size of a particular object by means of lines.

5) What is Engineering Drawing ?

A drawing which is worked out an engineer for the engineering purpose is known as Engineering Drawing.

6) What is a sketching ?

This is freehand expression of the graphic language.

7) What do you mean by First Aid ?

First Aid is immediate and temporary care given to a person who affected accidental injury or a sudden illness before the arrival of doctor.

8) What is an accident ?
An accident is a unexpected and unforeseen event which may or may not injury to a person or a machine tool.

9) What are the standard sizes of drawing board as per Indian Standards?

As per Indian Standards :1250×900,900×650,650×500,500×350,350×250 sizes are available.

10) What are the functions of a scale ?

(a) To measure distance accurately.
(b) For making drawing to scale either in full size, reduced size or enlarged size.


11) What is the use of mechanical engineer’s scale ?

This is flat or triangular shape and used for making drawings of machines and structural parts in 1/8, 1/4, 1/2 or full size.

12) What is a Vernier Scale ?

This is used to measure very small unit with greater accuracy. It consists of a primary scale and a vernier scale.Vernier scale slides on the primary scale.

13) What is Representative Fraction ?

It is the ratio of drawing to the object. R.F=Length of the object in the drawing /Actual length of the object.

14) What is Drafting machine(Mini Drafter) ?

It is a device to do drawing work neatly and quickly.An attachment provided to move any position and may be adjusted at any required height.

15) What is a lettering ?

Lettering is the presentation of information data on a drawing.

16) Why Gothic style lettering is universally used in industry ?

Because it is more legible than other styles.

17) What are Section lines ?

Section lines are thin lines and used to show the cut surface of an object in sectional view.

18) What is a Centre line ?

Centreline is a thin line in the form long and short dashes. It indicates area of symmetrical parts, circles and path of motion.

19) Explain briefly the following lines used in Engineering drawing ?

(a)Dimension Lines (b)Extension Lines (c)Leaders
Dimension lines are the thin lines used to indicate extents and direction of dimension. These are terminated with arrowheads.
Extension lines are also thin lines and it used to indicate the termination of a dimension.
Leaders are used to direct notes or identification symbols to feature on the drawing.

20) What are Cutting Plane Lines ?

These are thick lines used to indicate the location of cutting planes in sectioning and the viewing position of removed pieces.


21) What do you mean by Break Lines ?

It is used to limit a broken section. For short break an uneven freehand thick line is recommended and for long breaks a long thin ruled dashes joined by freehand ‘ Zig Zags’ are used.

22) What are Phantom Lines ?

These are thin lines composed of long dashes with pair of short dashes. Phantom Lines used to show adjacent parts, alternate positionsand the lines of motion.

23) State the difference between Size dimension and Location dimension ?

(a)Size Dimension :It describes the size of an object such as length ,width, thickness, depth, diameter etc.
(b)Location Dimension: A location dimension describes the location of constructional parts within an object .It includes location of holes, slots, grooves etc.

24) What is a functional dimension ?

This is expressed directly on the drawing which is essential to the function of the product.

25) What is the main advantage of chain dimensioning ?

Chain dimensioning can be used where the possible accumulation of tolerance does not cause danger to the functional requirement of the part.

26) Where is draft angle used ?

Generally draft angle is used in moldings and drop forgings, parts of which maybe left un-machined.

27) How are screw threads specified ?

It should be specify pitch and dimension with tolerances and also the distance to the end of full(parallel)threads.

28) What is a Polygon ?

It is plane closed figure having many sides and angles. A regular polygon has equal sides and equal angles.

29) Define Ellipse ?

It is a plane curve formed by a point moving so that the sum of its distances from two fixed points (foci) is constant and equal to major axis.

30) Define Parabola ?

Parabola is a curve which is generated by a point moving along a path equidistant from a point (focus)and a straight line(directrix).


31) Define Hyperbola ?

It is a curve which is generated by point moving so that the differences of the distances from any point of the curve to two fixed points(foci),is a constant equal to the transverse axis of the hyperbola.

32) What is an involute ?

Involute is a spiral curve made by a point on a perfectly taut string as it unwinds from around a shape such as a circle or polygon.

33) Define a Cycloid ?

It is a curve which is generated by a point in the plane of a circle that rolls along a straight line.

34) What is a Helix ?

It is a curve which is generated by a point moving at uniform rate around and advancing parallel to, or at varying distances from an axis.

35) What is meant by projection of an object ?

Representation of an object on paper is called projection of an object.

36) What do you mean by projectors ?

Projectors are the imaginary lines drawn from the object to the plane.

37) What is the plane of projection ?

It is the plane on which the projection of the object is taken.

38) Explain the principle of orthographic projection ?

It is the method of representing the exact shape of an object in two or more views on planes. In this projection all the projectors are parallel to each other and perpendicular to the plane of projection. Projectors are assumed to come from infinity. It is generally used in machine drawing.

39) What are the principle views of an orthographic projection ?

(a)Front view or Elevation(b)Top view or Plan (c)Side view

40) Which orthographic projection has been recommended by Bureau of Indian Standard(BIS) ?

Third angle projection


41) What are the planes of projection ?

Vertical plane(VP) and Horizontal plane (HP) are generally used in orthographic projection. These planes of an object are obtained to describe it clearly with all dimensions. These are known as principle planes and the position of an object can be fixed by following four quadrants:
(1) First Quadrant: It is above HP and in front of VP.
(2) Second Quadrant: It is above HP and behind VP.
(3) Third Quadrant: It is below HP and behind VP.
(4) Fourth Quadrant: It is below HP and in front of VP.

42) Explain position of views in First Angle Projection ?

In first angle projection the top view is positioned below the front view with the left side view of the object to the right side of the front view.

43) What is the position of views in Third Angle Projection ?

The top view appears above the front view with right side of the object to the right of the front view in third angle projection.

44) What do you mean by Pictorial Drawing ?

It is a graphic language of engineers which represents a real thing by means of picture view.

45) What are the commonly used various methods of pictorial projection ?

(a) Isometric projection
(b) Oblique projection
(c) Perspective projection.

46) What is meant by Oblique projection ?

It is the one view projection where the projectors may be at any angle except 90 degree with the plane of projection, but 45 degree projectors are generally used because projectors at 45 degree with plane of projection all the edges of the cube are in their true lengths in the oblique projection.

47) What is an Isometric drawing ?

This is drawn by using three axis. One axis is drawn vertically and the other two are at an angle of 30 degree (right and left) to the horizontal.

48) Explain Perspective projection ?

A perspective drawing is one which more nearly present an object as seen in an actual photograph or as it appears to the eye of the observer.

49) What is a sectional view ?

The cross section of an object obtained by passing an imaginary cutting plane through the object is called sectional view.

50) Why is it necessary to show the sectional view of an object ?

Because it shows clearly the internal shape of an object or interior details of a part can easily shown.


51) Is it essential to show all the hidden lines in dotted in a assembly drawing ?

Generally hidden lines are omitted from the sectional view and not essential to show all hidden lines in assembly drawing. If it is necessary to show more clearly a hidden part in the section or aiding in dimensioning the view, they may be drawn.

52) How are thin materials shown in sectional drawing ?

Thin materials such as sheets, gaskets and electrical sections are shown solid in section and adjoining parts should be separated by a small space.

53) What is meant by development ?

Development is the drawing of all the surfaces of an object on a plane to make a pattern. If it is folded or rolled it will form the required object. The main applications are in sheet metal work,sheet plastic fabrication and many other industrial applications.

54) What are the method of development ?

1.Parallel Line Development: It is used for patterns of prisms and cylinders.
2.Radial Line Development: This is used for surfaces of regular tapering forms such as pyramids and corns.
3.Triangulation Development: It is used when the connecting surface is neither prismatic nor pyramidal such as developing warped and double curved surfaces.

55) What are the production drawings ?

Production drawings are the drawings which are required for the fabrication of any product.

56) What is meant by assembly drawings ?

Drawing which shows how two or parts are assembled and identifies all the pieces which form the assembly is called assembly drawings.

57) What do you mean by detail drawing ?

It shows the essential shape, size and specifications required for the construction of each unit of a product.

58) What are the different types of detail drawings ?

1) Pattern detail drawings
2) Stamping detail drawings
3) Casting detail drawings
4) Welding detail drawings
5) Forging detail drawings

59) Why is a pictorial drawing shaded ?

To make the appearance of a pictorial drawing more natural .

60) What is meant by interpenetration of solids ?

If one solid penetrates into the other solid of the same or different cross section then surfaces of the both solids come in contact and outline of the penetrating solid can be seen which is called interpenetration of solid.