INTRODUCTION TO IQC

TOPIC

CONTENTSINTRODUCTIONPHYSICAL QUANTITIESMEASUREMENTBASIC METHOD OF MEASUREMENTSCLASSIFICATION OF UNITSSYSTEM OF UNITSSTANDARDS FOR MEASUREMENTINTERCHANGEABILITYINTERNATIONAL AND NATIONAL STD.STANDARDS OF MEASUREMENT

INTRODUCTIONInspection is the art of comparing material, product or performance with established standards.

Inspection measures the qualities of a product or service in terms of predecided standards. Products quality specified by strength, shape, hardness or by other parameters.

PHYSICAL QUANTITYAll quantity in terms of which

laws of physics can be expressed and which can be measured directly or indirectly are called physical quantity.

Physical Quantity further divided into two types:-

Extensive QuantitiesIntensive Quantities

Extensive Intensive

Extensive quantity: its magnitude is additive for subsystems (volume, mass, etc.

Intensive quantity: the magnitude is independent of the extent of the system (temperature, pressure, etc.)

MEASURMENTMeasurement is the presses of

comparison of an unknown quantity with a known fixed unit quantity of the similar nature.

Properties of measurementIt should be easy to reproduce.It should be easily accessible.It should be commonly

acceptable.It should not change with time

and from place to place.It should be well defined.

BASIC METHOD OF MEASURMENT

These are two types of basic method of measurement:-Direct comparisonIndirect comparison

CLASSIFICATION OF UNITSFUNDAMENTAL UNITSDERIVED UNITS

FUNDAMENTAL UNITS A set of fundamental units is a set of units for 

physical quantities from which every other unit can be generated.

In the language of measurement, quantities are quantifiable aspects of the world, such as time, distance, velocity, mass, temperature, energy, and weight, and units are used to describe their measure. Many of these quantities are related to each other by various physical laws, and as a result the units of some of the quantities can be expressed as products (or ratios) of powers of other units (e.g., momentum is mass times velocity and velocity is measured in distance divided by time). These relationships are discussed in dimensional analysis. Those that cannot be so expressed can be regarded as "fundamental" in this sense.

DERIVED UNITThe units of all physical

quantities which can be expressed in terms of fundamental units are called derived units.

SYSTEM OF UNITSC.G.S. SYSTEMF.P.S. SYSTEMM.K.S. SYSTEMS.I. UNITS

C.G.S. SYSTEM:-It is also known as “French system”. In this system the unit of length in centimeter, unit of mass is gram and unit of time is second.

F.P.S. SYSTEM:-It is also known as “British system”. It uses foot, pound and second.

M.K.S. SYSTEM:-It is also known as “Metric system”.it is a system of measurement in which the fundamental units of measurement of length, mass, and time are meter, kilogram and second respectively.

S.I. UNITS:-French name of this system is “System international” units, abbreviated as s.i. unit. This system is an Improved and extended version of M.K.S. system of unit.

Standard for measurmentPrimary standred- Primary

standred are absolute standerds of high accuracy that are used as refrence standred.

Secondary standred- Secondary standred are close copies of primary standred and are used in industries for measurment.

Tertiary standred- These are used for refrence purpose in laboratories and workshop.

Working standred- Working standred are used as major tools of measurment in ameasurment laboraratory.

INTERCHANGEBILITYInterchangebility refers to assembling a number of mating component taken at random from stock, so as to build up a complete assembly without fitting or adjustment. Types of interchangebility:-I. Full or universal interchangeabilityII. Selective assemblyIII. Matched fits

INTERNATIONAL OR NATIONAL STANDREDInternational standred- The

international standred are defined on the basic of international agreement.The international standred are maintained at the international Bureau of weight and international organizatin for standred.(ISO)

NATIONAL STANDRED- The Bureau of indian standred(BIS)is on the same pattern as british standred institution(BSI).Its principal object are:

1. To use for the improvment.2. To set up standred of quality and

dimension.3. To samplify production and

distrbution.

STANDRAD OF MEASURMENT

These days two standerd system of linear measurement ,English(yard) and metric(meter) are in general use throughout the world.For linear measurement the various standerd known are:-Line standardEnd standardWave length standard

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