Transcript Slide 1

COMPARATORS
Introduction:
• Comparator is an instrument used for
comparing the dimensions of a component
with a standard of length
• Purpose of a comparator, in general, is to
detect & display the small differences b/w the
unknown linear dimension & length of the
standard
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Lecture # 21 & 22
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COMPARATORS
Essential Parts of Comparators:
1. Fixed surface from which all measurements are taken
2. A very sensitive indicator which will show the
movement of a sliding piece usually terminating in an
anvil with curved surface
3. Some means of setting the curved face
Arrangement of above parts is used to measure the
difference b/w the length or diameter of a component &
a standard of length, usually made up of slip gauges
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COMPARATORS
The Important & essential function of the
instrument is to MAGNIFY or AMPLIFY the
small input displacements to that it is
displayed on an analogue scale
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COMPARATORS
Desirable Features of a Comparator:
1.
2.
3.
4.
5.
It should at least be able to record variations of 0.0025mm
Recording scale should be linear
Maximum rigidity
Maximum compensation of temperature effect
Neither lag nor backlash in the movement of the plunger
& recording mechanism
6. Indicator should be constant in its return to zero
7. Measurement pressure should be low & constant
8. Instrument should be capable of a wide measuring range
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COMPARATORS
Uses of Comparators:
1. To inspect newly purchased gauges
2. In mass production, where components are
to be checked at a very fast rate
3. As laboratory standards from which working
or inspection gauges are set & correlated
4. As working, to prevent work spoilage & to
maintain required tolerance at all important
stages of manufacture
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Lecture # 21 & 22
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COMPARATORS
Types of Comparators:
Most common commercially available comparators
can be classified into the following types:
1. Mechanical comparators
2. Optical comparators
3. Electrical & Electronic comparators
4. Fluid displacement comparators
5. Pneumatic comparators
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Lecture # 21 & 22
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COMPARATORS
Types of Comparators:
A combination of magnifying principles has lead
to the development of a few more types of
comparators, which are:
6.
7.
8.
Mechanical-Optical comparators
Electro-mechanical comparators
Multi-check comparators
The most interesting & important component on a
comparator is the indicating unit, & instruments are
made in which the operation for this unit depends
on mechanical, electrical or pneumatic principle
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Lecture # 21 & 22
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MECHANICAL COMPARATOR
• The mechanical comparators utilize
mechanical methods of magnifying, the
movement of the contact plunger; their
manufacture requires a high degree of skill &
accuracy.
• The usual magnifications of the mechanisms
range from about 250 to 1000.
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MECHANICAL COMPARATOR
• Some of the comparator which belong to this
class are:
1. Dial indicator
2. Reed type comparator
3. Sigma Comparator
4. Johnson Mikrokrator
5. Eden Rolt Millionth Comparator
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Lecture # 21 & 22
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MECHANICAL COMPARATOR
1. Dial Indicator:
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Lecture # 21 & 22
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MECHANICAL COMPARATOR
1.Dial Indicator: (different uses)
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Lecture # 21 & 22
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MECHANICAL COMPARATOR
1. Dial Indicator: (Various Uses)
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Lecture # 21 & 22
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MECHANICAL COMPARATOR
1. Dial Indicator:
a. Principal parts:
As demonstrated
(more see page# 186)
b. Principal of Operation: As demonstrated
(more see page# 186)
c. Dial Indicator Fitted to Pillar stand: As
demonstrated (more see page# 187)
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Practical # 06
Object: To Learn Use of Vernier Height Gauge
Aparatus: Vernier Height Gauge
Procedure: As demonstrated/written in
practical handout
Observation:
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Sr#
Object Name
Lecture # 21 & 22
Size measured
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Practical # 06
Vernier Height Gauge:
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Lecture # 21 & 22
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Practical # 06
Vernier Height Gauge:
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Lecture # 21 & 22
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