Term Paper Presentation1

8/22/2019 Term Paper Presentation1

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Lovely professional universityPresentation of term paper

ByKamlesh kumar

Roll no.RM2009A06

Sub. code:-MEC 314

Regd. No:-11004437


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Construction features and

use of instruments forprecision measurements


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Outline

Introduction

Precision measuring instrument

Micrometer

Height gauges

Conclusion

References


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Introduction

Measuring instruments: - A measuring instrument is simply a device

for determining the value of some particular quantity or condition.

Generally the measuring instruments are classified as follows: -

1) On the basis of function

a) Length measuring instrumentsb) Angle measuring instruments

c) Surface-roughness- measuring instruments

d) Geometrical-form-checking instruments

2) On the basis of accuracy

a) Most accurate instrument

b) Moderate accurate instrument


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c) Below Moderate accurate instrument

3) On the basis of precision

a) Precision measuring instruments

b) Nonprecision measuring instruments

Precision measuring instruments includes :-

1) Vernier Calipers

2) Micrometers

a) Inside Micrometer Caliper

b) Outside micrometer

c) Depth micrometer

3) Height Gauge


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Accuracy:- Accuracy is the closeness of agreement between a test

result and the accepted reference value. The accuracy of

measurements means conformity to the truth.

Precision:- It is a measure of the reproducibility of the

measurements, given a fixed value of a quantity or the degree of

exactness for which an instrument is designed or intended to perform.


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Difference between accuracy and precision

Sl.no.

Accuracy Precision

1. It is the closeness with

the true value of the

quantity being measured.

It is a measure of the

reproducibility of the

measurements.

2. Accuracy is necessary

but not sufficient

condition for precision.

Precision is necessary but not

a sufficient condition for

accuracy.

3. Accuracy can be

improved.

Precision cannot be

improved.

4. Single measurement is

needed.

Multiple measurements are

needed.


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Accuracy and precision


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Precision measuring instrument

Vernier caliper

A vernier caliper (or vernier) is a common tool used in laboratories

and industries to accurately determine the fraction part of the least

count division. The vernier is a convenient tool to use when

measuring the length of an object, the outer diameter (OD) of a

round or cylindrical object, the inner diameter (ID) of a pipe, and

the depth of a hole.


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Simple vernier caliper


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Digital vernier caliper


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Advantages of vernier caliper

A large range of sizes can be measured by one caliper.

The wearing parts are the jaws and usually these are hardened.

Therefore, provided that the jaws are undamaged the loss of

accuracy due to usage is low.

Limitation of vernier caliper

Cannot measure very small measurements.

The jaws are comparatively light and may spring out ofalignment if too much pressure is applied.


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Micrometer

Micrometers can make measurements that must be very precise.

They are more reliable and more exact than calipers. Standard

micrometers can measure distance to the nearest one-thousandth ofan inch. Some micrometers have a vernier scale. These micrometers

can measure distance to the nearest ten-thousandth of an inch. The

measurement is usually written as a decimal.


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Standard micrometer


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Digital micrometer


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Different types of instruments


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Parts of micrometer

The essential parts of the instruments shown in Figure , consist of

(a) Frame

(b) Anvil and spindle

(c) Screwed spindle

(d) Graduated sleeve or barrel

(e) Thimble

(f) Ratchet or friction stop

(g) Spindle clamp


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Height Gauges

This uses the same principle of vernier caliper and is

used especially for the measurement of height. It is

equipped with a special base block, sliding jawassembly and a removable clamp. The upper and lower

surfaces of the measuring jaws are parallel to the base,

which make possible to measure both over and under

surfaces.


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Height Gauges


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Digital Height Gauges


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Conclusion

As the competition in the market has increased, it has become

necessary for manufactures to produce the product having high

accuracy and precision. To achieve this level of precision, the

special precision instruments must be used. These instruments

include vernier caliper, micrometer, height gauges, which has been

already discussed. Working and construction of each instrument are

different and used to measure the different variable. These

instrument have their own property and used according to the

requirement .if more accuracy is required we use micrometer

instead of vernier caliper.


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References

Metrology and Measurements by Anand K Bewoor and Vinay A

Kulkarni, page 9

http://www.ignou.ac.in/upload/Unit-5-62.pdf

Metrology and Measurements by Anand K Bewoor and Vinay A

Kulkarni, page 392.

http://www.colorado.edu/geography/gcraft/notes/error/error.html

http://www.webpal.org/SAFE/aaarecovery/5_simple_technology

/Precision%20Measuring%20Instruments.pdf

http://www.ou.ac.lk/eng/mech/images/stories/CourseResources/

metrology presentation.pdf.

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