Minimum Basics of mechanical engineering

1. Presentation by
K. Prudhvi Rahul
BTG Batch - 8

2. Topics To Be Covered
• Basics of mechanical engineering
• Units and measurements
• Measuring instruments
• Mechanical equipment
• Manufacturing process
• Codes and standards
• Measuring equipment & techniques
• Hvac System
• Heat transfer
• Material Handling
• Mechanical properties of materials
• IC engines
• Hydraulic machines
• Strength of materials

3. What is mechanical engineering?
• Mechanical engineering is the
discipline that applies the
principles of engineering,
physics, and materials
science for the design,
analysis, manufacturing, and
maintenance of mechanical
systems. It is the branch of
engineering that involves the
design, production, and
operation of machinery

4. Mechanical Engineer?
• Mechanical engineers create
and develop mechanical
systems for all of humankind.
Concerned with the principles
of
• Force
• Energy
• Motion
• Mechanical engineers use their
knowledge of design,
manufacture, and operational
processes to advance the world
around us — enhancing safety,
economic vitality and
enjoyment throughout the
world.

5. What Is a Force?
• A force is a push or pull upon
an object resulting from the
object's interaction with
another object.
• Mainly there are two types of
forces:
• Contact Forces
• Non Contact Forces
• Force is Measured in Newtons

6. FORCE
Force
Contact
Friction
Air
Resistance
Normal
Force
Applied
Force
Tension
Force
Spring
Force
Non
Contact
Gravitational
Force
Magnetic
Force
Electrical
Force

7. Frictional Forces & Applied Forces
• Whenever an object moves
against another object, it feels
frictional forces.
• These forces act in the
opposite direction to the
movement.
• Friction makes it harder for
things to move.
• The pushing or pulling force
we were applying on an object
is called as Applied Forces.

8. How Many Types Of Friction?
1
2
3
4

9. Helpful Frictional Forces &
Unhelpful Frictional Forces
• Friction can be useful:
• Friction between tires and the road stop cars from skidding.
• Friction between the brakes and wheel help bikes and cars slow
down.
• Friction can also be unhelpful:
• If you don't lubricate your bike regularly with oil, the friction in
the chain and axles increases. Your bike will be noisy and
difficult to pedal.
• When there is a lot of friction between moving parts, energy is
lost to the surroundings as heat.

10. Air Resistance
• Air resistance is caused by
the frictional forces of the
air against the vehicle.
• The faster the vehicle
moves, the bigger the air
resistance becomes.

11. Normal Force
• When a body exerts a force
on another, the second
provides a reaction which
acts perpendicular to the
surface of 2nd body.

12. Tension Force
• The Tension force is the force that is
transmitted through a string, rope, cable or wire
when it is pulled tight by forces acting from
opposite ends.
• The tension force is directed along the length of
the wire and pulls equally on the objects on the
opposite ends of the wire.

13. Spring Force
• The spring force is the force exerted by a compressed
or stretched spring upon any object that is attached to
it. An object that compresses or stretches a spring is
always acted upon by a force that restores the object
to its rest or equilibrium position.

14. Hooks Law
• Hooke's law states that the force F
needed to extend or compress a
spring by some distance X is
proportional to that distance.
• F = KX where K is a constant of the
spring: its stiffness, and X is the
deformation of the spring.
• F= -KX When the direction of the
restoring force is opposite to that of
the displacement.

15. Non Contacting Forces
• Gravitational Forces: Newton's law of universal
gravitation states that any two bodies in the universe
attract each other with a force that is directly
proportional to the product of their masses and
inversely proportional to the square of the distance
between them.
• F is the force between the masses;
• G is the gravitational constant
(6.674×10−11 N · (m/kg)2);
• m1 is the first mass;
• m2 is the second mass;
• r is the distance between the centers of the masses.

16. Lorenz Force
• Lorentz force: It is the
combination of electric and
magnetic force on a point
charge due to
electromagnetic fields. If a
particle of charge q moves
with velocity v in the
presence of an electric field
E and a magnetic field B,
then it will experience a force
• F = q E + q v × B

17. What Is Energy?
• The ability of a system to
perform work.
• Energy is a property of objects
which can be transferred to
other objects or converted into
different forms.
• Law Of Conservation Of
Energy: energy can be neither
created nor be destroyed.
• Energy is measured in Joules.

18. Work
• Work is said to be done on an object when the
force causes displacement of the object.
• Work is the product of the force applied on an
object and the displacement of the object.
• W= Force x Displacement
 Displacement: is an
object's change in
position considering its
starting position and
final position.
 Work is measured in
Joules

19. Types Of Energy

21. Mechanical Energy
• Mechanical energy is
the sum of kinetic and
potential energy in an
object that is used to do
work.
• In other words, it is
energy in an object due
to its motion or position,
or both.

22. Kinetic Energy
• kinetic energy is the
energy that the body
possesses due to its
motion.
• KE= 1/2MV2
• Where M is the
mass and V is the
speed (or the
velocity) of the body.

23. Potential Energy
• The energy stored in an
object by the virtue of its
motion.
• The amount of gravitational
potential energy an object
has depends on its height
above the ground and its
mass.
• PE= mgh
• Where m is Mass, g is
gravitational force, And h is
height of the object.

24. Motion
• Motion is a change in
position of an object with
respect to time.
• Motion is typically described
in terms of displacement,
distance, velocity,
acceleration, time and
speed.
• It is measured in relationship
to point of reference.

25. Motion Types(DOF)

26. Random Motion
• Random motion, also
known as Brownian
motion, is the
movement of atoms and
molecules.
• Gas is having random
motion, because of the
molecules move in
different directions.
Randon Motion Of Gas
Particles

27. Translational Motion
• Translational motion is the movement of an
object from one point to another through space.
• Three types of translational motions:
• Rectilinear
• Curvilinear
• Circular

28. Rotational And Oscillatory
• Rotational motion is
an object moves
around an axis
passing through its
body.
• Oscillatory motion is
something that
moves back and
forth repeatedly.

29. DOF(Degrees of freedom)
• DOF is number of
independent motions that
are allowed to the body.
• In case of a mechanism
number of possible
independent relative
motions between the
pieces of the mechanism.
• Mostly used in robotics.

30. How many degrees of freedoms ?
• There are six degrees of a freedom
for an object in space.

31. DOF of a ship
• The motion of a ship at sea has the six degrees of
freedom of a rigid body, and is described as:
• Translation and rotation:
• Moving up and down (elevating/heaving);
• Moving left and right (strafing/swaying);
• Moving forward and backward (walking/surging);
• Swivels left and right (yawing) ;
• Tilts forward and backward (pitching);
• Pivots side to side (rolling).

32. DOF of Plane
• A plane is also having six degrees of
freedom.

33. Measurements And Units

34. Measurement
• Measurement is the standard which
is used for comparison must be
defined accurately, And it should be
universally accepted.
• Measurement is the process of
comparing unknown magnitude of
certain parameter with the known
predefined standard of that
parameter.

36. How large is a millimeter?
•The
width of
a pin

37. How large is a centimeter?
The width
of the top
of your
finger

38. How large is a meter?
About the
width
of one &
1/2 doors
1 meter

39. How large is a milliliter?
About a
drop of
liquid

40. • Units of Length
• 10 millimeters = 1 centimeter
• 10 centimeters = 1 decimeter
• 10 decimeters = 1 meter
• 1000 meters = 1 kilometer
• Units of Weight
• 10 milligrams = 1 centigram
• 10 centigrams = 1 decigram
• 10 decigrams = 1 gram
• 1000 grams = 1 kilogram
• 1000 kilograms = 1 metric ton
Measurements Of Length And Weight

41. Units
• Units are standards for measurement
of physical quantities that need clear
definitions to be useful.
• There are mainly two types of units
• Basic Units
• Derived Units

42. Basic Units
• The International System of Units (SI) defines
seven units of measure as a basic set from
which all other SI units are derived. The SI
base units and their physical quantities are:

43. Derived Units

44. Derived Mechanical Units

45. Features of Measured Quantities
• When we measure a number, there are
physical constraints to the measurement.
• Instruments and scientists are not perfect,
so the measurement is not perfect (i. e., it
has error).
• The error in the measurement is related to
the accuracy and the precision of the
measurement

46. Accuracy and Precision
Accuracy – how close the measurement
is to the “true” value (of course we
have to know what the “true” value is)
Precision – is a measure of how closely
individual measurements agree with
one another.

47. Accuracy and Precision

48. Equations for Precision and Accuracy
1. Precision
2. Accuracy
Absolute Error
% AE = (True value-Avg Value) X
100
True Value

49. Measuring Instruments
• A measuring instrument is
a device for measuring a
physical quantity.
• In the physical sciences,
quality assurance, and
engineering, measurement
is the activity of obtaining
and comparing physical
quantities of real-world
objects and events.

50. Rulers
• Rulers
– Simple tools to measure straight-line
distances where tolerances are not a major
factor
– Can be made of metal, plastic, or wood
– Typical rulers are 6 inches or 12 inches
– Tolerance: is the permissible limit or limits
of variation.
– In mechanical engineering the space
between a bolt and a nut or a hole Is the
Tolerance

51. Tolerance

53. Calipers
• Calipers: Engineers and machinists
frequently use calipers to secure
accurate measurements of inside and
outside diameters.
• A caliper can be as simple as a
compass with inward or outward-
facing points

54. Calipers

55. Feeler Gauges
• Feeler Gauges
– to measure the clearance between two
parts
– Used for measuring “gaps” or the space
between two objects
– Proper usage requires practice

56. Feeler Gauges

57. Feeler Gauges used for
• Valve lash
• Measure spark plug gap
• Head flatness
• Thrust distance in Crankshaft
• Ignition point gap (Old Vehicles)

58. Feeler gages are principally used in determining
clearances between various parts of machinery.
Probably the most common use is determining valve
clearance. Various blades are inserted between the
tappet and the push rod until a blade of the feeler gage
is found that will just slide between the two surfaces
without too much friction or sticking. The thickness of the
blade then determines the clearance. Or, a particular
feeler of proper thickness may be selected and the
tappet adjusted until the feeler will just slide between the
tappet and push rod with out catching.

59. Measuring Valve Clearance
Valve lash
Thrust distance in
Crankshaft
Head flatness
Spark plug gap

60. Feeler Gauges with strip
Such a gage consists of thin blades of
metal of various thicknesses. There is
generally a blade or strip for each of
the most commonly used thicknesses
such as 0.002 inch, 0.010 inch, and
.015 inch. The thickness of each
blade is generally etched on the
blade

61. Some other models of Feeler Gauges

63. Micrometers
• Micrometer is a caliper to obtain
measurements accurate to 1/1000 of an inch.
• This instrument is particularly useful for
measuring relatively short lengths and the
diameter of bolts or cylinders.
• The common commercial micrometer
consists of a frame, an anvil or fixed
measuring point, a spindle, a sleeve or barrel,
a thimble and a rachet.

64. Micrometer

65. Types of micrometers
• Outside micrometer typically used to
measure wires, spheres, shafts and blocks.
• Inside micrometer used to measure the
diameter of holes.
• Depth micrometer measures depths of
slots and steps.

66. Outside Micrometer

67. Inside Micrometer

68. Depth Micrometers

69. Telescopic Gauges
 Used with outside micrometers to
measure inside diameters.
 Various lengths and T-shaped.
 Extensions are spring-loaded.
 These wont contain individual
markings for measurement

70. Telescoping gages

71. Telescopic gauge

72. Telescoping Gauges
• Telescopic
Gauges
– Leg has a
rotatable handle to
lock extensions in
place.
– Once gauge is
removed,
measured with
outside
micrometer.

73. Small Hole Gauges
• To measure small holes
• Gauge is straight with a screw handle
on one end and a split ball on other.
• Handle is turned to expand ball.
• These wont contain individual
markings for measurement
– Removed and measured with a
micrometer

74. Small Hole Gauges

75. Small Hole Gauge

76. Go/No Go gauge
• Go/No Go gauge refers to an inspection tool used
to check a work piece against its allowed
tolerances.
• Its name is derived from two tests: the check
involves the work piece having to pass one test
(Go) and fail the other (No Go).
• It does not return a size or actual measurement in
the conventional sense, but instead returns a state,
which is either acceptable (the part is within
tolerance and may be used) or unacceptable (the
part must be rejected).

77. Types Of Go Gauges
circular
Treaded
nut
Treaded
Hexagonal

78. Some different types

79. Go Gauge

80. Dial Indicators
• Dial Calipers
– For inside, outside, and
depth measurements
– Manual scales or digital
– can measure in 0.001
inch increments
– Metric can measure in 2-
millimeter increments

81. Dial Indicator
• A plunger moves in and out from
the body of the indicator and
rotates the measuring needle on
a dial face.
• Dial indicators usually have
either a 1" or 2" range and are
calibrated in increments of
.001". A smaller dial reads each
revolution of the larger dial in
increments of 0.100".

82. Dial Gauges Uses
• Centering cylindrical stock in a 4-jaw chuck
• Determining accuracy of lathe or mill
alignment
• Determining runout of lathe spindle and
chucks
• Monitoring depth of drilled holes
• Monitoring vertical movement of milling
head
• Determining if edges of a rectangular
workpiece are parallel

84. Pressure and Vacuum
Measurements
• Pressure Gauges
– Measures amount of pressure applied to a
closed, sealed system
– Fitted into pressure line with appropriate
fittings
– A manometer is an instrument that uses a
column of liquid to measure pressure,
although the term is currently often used to
mean any pressure measuring instrument.

85. Pressure manometer

86. Pressure and Vacuum
Measurements
• Vacuum Gauges
– Mechanical gauge measures difference
between atmospheric pressure and current
state of system
– A vacuum gauge is used to measure the
pressure in a vacuum.
– it is possible to measure system pressure
continuously from 10 mbar down to
10−11 mbar.

87. Vacuum Manometer