ENGINEERING METROLOGY

ENGINEERING METROLOGYQAS 0312

GMI | Production Technology

ENGINEERING METROLOGYCourse Objective

Students should be able to:Explain the basic concepts of testing,

measuring and gauging procedures used in engineering.

Perform inspection of linear and angular measurement by using various types of measuring instruments and gauging methods.


ENGINEERING METROLOGYMain Topics

1. Fundamentals of Metrology2. Basic Inspection and Procedures3. Measurement Errors4. Vernier Caliper5. Micrometer6. Mechanical Dial Indicator7. Gauge Blocks8. Surface Plate Inspection9. Instruments for Testing Angles10. Gauges11. Profile Projector12. Surface Roughness Measurement13. Measurement of Threads


ENGINEERING METROLOGY

Assessment:CMM – 40%Metrology – 50%KQ – 10%

1. PBL 1 : 10%2. PBL 2 & Practical : 25%3. Test : 15%


FUNDAMENTALS OF METROLOGYCHAPTER 1


FUNDAMENTALS OF METROLOGYLearning Objectives

Define the term metrologyDifferentiate between accuracy and precisionExplain the needs and functions of inspectionList the objectives of metrologyIdentify SI units and dimensionsPerform conversion of SI units


FUNDAMENTALS OF METROLOGYWhat is Metrology?

Science of measurement.Concerns in correctness of measurement

Precision Accuracy

Methods and techniques of measurement based on agreed units and standards


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Robin Hood's Merry Man missed the

bull's-eye but the 3 attempts were near

each other.

Precise but inaccurate

Stone age man missed the bull's-

eye and the 3 attempts were not near each other.

Inaccurate and imprecise (unrepeatable)

Precision vs Accuracy

Precision vs Accuracy (cont)

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Olympic archer hits the bull's-eye 3

times!

Accurate and precise

American Indian's 3 attempts are near the bull's-eye, but

were not near each other.

Accurate but imprecise

FUNDAMENTALS OF METROLOGYWhy is Metrology important?

Standardization in tradeEliminating technical barriers in trade,

manufacturing industry, construction etc etc.Promoting awareness to Quality Assurance

What is Inspection?Formal or Official examination of products with

the use of accurate (calibrated) measuring instruments


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To determine good or bad parts

To achieve interchangeability

To improve and develop precision measuring

instruments

Needs and Functions of Inspection

To support the manufacturing department

FUNDAMENTALS OF METROLOGYTo determine good and bad parts

1. To determine the conformance of products to specifications or requirements – important in assisting manufacturing process and assuring of quality.

2. In industry, inspection is used for selection of products whether it can be ‘accepted’ or ‘rejected’

3. To maintain the product quality – meet customer satisfaction index


FUNDAMENTALS OF METROLOGYTo achieve Interchangeability

1. Interchangeability – products should be able to fit and mate if chosen randomly from different manufacturers

2. Examples: Screws and threads, nuts and bolts, pipes and pressure vessels, pnuematic and hydraulics fittings/valves, etc.

3. Can be achieved by means of measuring and gauging

1. Calipers, micrometers, thickness gauge, radius gauge etc

2. Plug gauge, pin gauge, ring gauge etcGMI | Production Technology

FUNDAMENTALS OF METROLOGYTo improve and develop precision measuring

instruments1. Due to demands of high accuracy and

precision works or products2. Promote spirit of competition between

manufacturers to produce high quality precision parts


FUNDAMENTALS OF METROLOGYTo support the manufacturing department

1. Functions of inspection in manufacturing industries

Conformity of product’s appearance and functions Conformity of product’s dimensional specifications Conformity of product’s performance Providing data for product’s improvement analysis

Production process Manpower skills Material analysis Machines accuracy and maintainance


OBJECTIVES OF METROLOGY

Ensure products designed – within process spec & measuring instrument capabilities. (products)

Determine process capabilities. (processes) Determine the measuring instrument capabilities.

(instruments) Reduce the cost of rejects & rework. (products) Minimize the cost of inspection. (products) Maintenance of the accuracy of measurement.

(instruments)


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Principles of MetrologyFundamentals Units and standardsInternational System of Units (SI)

- established in 1960- by CGPM (General Conference of Weight and Measures)- e.g : Force Newton N (kgm/s2)

advantages of coherency of SI units.

same system & units of measurement regardless of industries

minimum of conversion factors

FUNDAMENTALS OF METROLOGYPrinciples of Metrology

Fundamentals Units and Standards Language of measurement and must be constant

worldwide SI base units:

1. Length : Meter (m)2. Mass : Kilograms (kg)3. Time : second (s)4. Current : Ampere (A)5. Thermo. Temp : Kelvin (K)6. Amount of subs. : Mole (mol)7. Luminous intensity : Candela (cd)



SI Prefixes


Prefixes Symbol Multiplier Prefixes Symbol Multiplier

peta P 1015 deci d 10-1

tera T 1012 centi c 10-2

giga G 109 mili m 10-3

mega M 106 micro µ 10-6

kilo k 103 nano n 10-9

hecta h 102 pico p 10-12

deka da 101 femto f 10-15


SI derived units:1. Area : square meter (m2)2. Volume : cubic meter (m3)3. Velocity : meter per second (m/s)4. Acceleration : meter per square sec.

(m/s2)5. Force : Newton (N)6. Luminance : candela per square meter (cd/m2)


FUNDAMENTALS OF METROLOGYConvert the following unit:

a) 0.88dm to mm:b) 200µm to Mm : c) 15mg/Gm³ to kg/cm³ :


ENGINEERING METROLOGY

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