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# Metrology

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### Metrology

1. 1. PREPARED BY: MUHAMMAD ANSAB 2nd YEAR (MECHANICAL) BATCH-10
2. 2. CONTENTS Definition of metrology  History of measurement  Importance of measurement System  Function of inspection department  Advantages of inspection department  Tools for inspection  Measuring devices 
3. 3. DEFINITION OF METROLOGY  Metrology is the science of Measurement.  Metrology is the science concerned with the establishment, reproduction, conversion & transfer of units. 2. Types of Metrology Scientific Metrology Industrial Metrology 3. Legal Metrology 1.
4. 4. HISTORY OF MEASUREMENTS There are mainly three quantities which are use to measure, named as : 1. Length 2. Mass 3. Time.
5. 5. 1. Length  Length is the most necessary measurement in everyday life.  4. There are many units of length, for example: Inch Foot Mile Yard  The most recently and widely used unit of length is meter  It is defined as the distance between two lines on a specific platinum– iridium bar stored under controlled conditions. 1. 2. 3.
6. 6. 2. Mass o There are many units to measure a quantity named as mass. o But the most widely used unit to measure mass is gram. o Gram was originally derived from the mass of one centimeter cube of water. o In 1887 the unit of mass Kilo Gram (KG) is defined as the mass of a specific platinum–iridium alloy cylinder kept at the International Bureau of Weights and Measures at Sevres, France.
7. 7. 3. TIME o Before 1960, the standard of time was defined in terms of the mean solar day for the year 1900. o “A solar day is the time interval between successive appearances of the Sun at the highest point it reaches in the sky each day.” o In 1967, the second was redefined which uses the characteristic frequency of the cesium-133 atom as the “reference clock.” o The second (s) is now defined as 9 192 631 770 times the period of vibration of radiation from the cesium atom.
8. 8. IMPORTANCE OF MEASUREMENT SYSTEMS There are three standard systems which are used to measure any quantity, named as: 1. 2. 3. MKS CGS FPS
9. 9. 1. MKS  The metric system, more more formally called the meter-kilogramsecond (MKS or mks) system of units, is based on three fundamental units: • The meter (m) that quantifies displacement. The kilogram (kg) that quantifies mass. The second (s or sec) that quantifies time. • •  The metric system is formally replaced by the very similar Standard International System of Units ( SI ).
10. 10. 2. CGS o The centimetre–gram–second system (abbreviated CGS or cgs) is a variant of the metric system of physical units. It is based on: 1. Centimetre as the unit of length. 2. Gram as a unit of mass. 3. Second as a unit of time. o The sizes of many CGS units turned out to be inconvenient for practical purposes. o The units gram and centimetre remain useful as Prefixed units within the SI system.
11. 11. 3. FPS  The foot–pound–second system or FPS system is a system of units built on the three fundamental units. • • Foot for length. Pound (avoirdupois) for either mass or force. Second for time.  It is also called British Engineering System. •
12. 12. FUNCTION OF INSPECTION DEPARTMENT  An inspection determines if the material or item is in proper quantity and condition and if it conforms to the applicable or specified requirements.  Inspection is generally divided into three categories: 1) Receiving inspection (2) In-process inspection (3) Final inspection
13. 13.  In quality control (which is guided by the principle that "Quality cannot be inspected into a product")  The role of inspection is to verify and validate the variance data, it does not involve separating the good from the bad.
14. 14. ADVANTAGES OF INSPECTION DEPARTMENT Inspection are used in most of fields which shows the advantages of inspection department. Some are as follows : 1. IN GOVERNMENT In government and politics, an inspection is the act of a monitoring authority administering an official review of various criteria (such as documents, facilities, records, and any other assets) that are deemed by the authority to be related to the inspection.
15. 15. 2. IN ROAD VEHICLES A vehicle inspection, e.g., an annual inspection, is a necessary inspection required on vehicles to conform with laws regarding safety, emissions, or both. 3. IN ENGINEERING (MECHANICS) • • Quality related inspection is an essential part of quality control. A mechanical inspection is usually undertaken to ensure the safety or reliability of structures or machinery.
16. 16. 4. IN MEDICAL A medical inspection is the thorough and unhurried visualization of a patient, this requires the use of the naked eye. 5. IN Real Estate A property inspection is the examination for purposes of evaluating a property's condition. In purchasing property, a "whole house inspection" tries to detect defects in the property.
17. 17. TOOLS FOR INSPECTION DEPARTMENT There are many tools for inspection but some tools are describe as under: 1.Caliper There are several different types of calipers designed to measure length, depth, internal, and external dimensions. Calipers can also be used to transfer dimensions from one object to another. 2.Bore Gage  Take an internal diameter measurement or compare to a pre-determined standard.
18. 18. 3.Fixed Gage  Used only to compare an object to a standard, fixed gages can measure attributes such as angle, length, radius, bore size, thickness, and other parameters. 4.Micrometer These dimensional inspection hand tools can use mechanical, digital, laser, dial, or scale technology to precisely measure length, depth, thickness, diameter, height, roundness, or bore.
19. 19. 5.Protractor Measure angles with a variable protractor or compare the angle of an object to a standard with an angle gage. 6.Indicator and Comparator The precision movement of a spindle or probe is amplified so the results can be displayed digitally or on a dial or column.
20. 20. 7.Air metrology Instruments  Thickness, depth, diameter, roundness, taper, and bore can be measured by calculating changes in pressure or air flow. 8.Ring Gage Typically used as a pass/fail test, ring gages can be threaded, smooth, or tapered to test the size of pins, threaded studs, and shafts.
21. 21. 9.Length Gage  Electronic or mechanical, these devices are used to measure or compare the length of an object. 10.Thread Gage The spacing, shape, size, and geometry of a thread can be verified or measured with a thread gage.
22. 22. MEASURING DEVICES  A measuring instrument is a device for measuring a physical quantity.  Measuring devices are classified as: Angular measuring devices Linear measuring devices 1. 2.
23. 23. 1. ANGULAR MEASURING DEVICES  There are a wide variety of geometric features that are measured in angular units. These varieties include angular separation of bounding planes, angular spacing conditions related to circle, digression from a basic direction etc. It has further two types : i. Line Standard Angular Measuring Device ii. Face Standard Angular Measuring Devices
24. 24. i. Line Standard Angular Measuring Device 1.Protractor o o o It is the simplest instrument for measuring angles between two faces. It consists of two arms and an engraved circular scale. The two arms can be set along the faces between which the angle is to be measured.
25. 25. 2. Universal Bevel Protractor o o o It is an angular measuring instrument capable of measuring angles to within 5 min. The name universal refers to the capacity of the instrument to be adaptable to a great variety of work configurations and angular interrelations. It consists of a base to which a vernier scale is attached.
26. 26. ii. FACE STANDARD ANGULAR MEASURING DEVICES 1. Sine Bar o A sine bar consists of a hardened, precision ground body with two precision ground cylinders fixed at the ends. o The axes of the two rollers are parallel to each other. o The operation of a sine bar is based on known trigonometric relationship between the sides and the angle of a right angle triangle. o The angle is calculated by using the sine rule.
27. 27. o Sine block itself is not a measuring instrument. It acts as an important link in the angle measuring process.
28. 28. 2. LINEAR MEASURING DEVICES 1. Vernier Caliper Vernier Caliper can be used to measure diameter, thickness very accurately.
29. 29. Different Parts of Vernier Caliper Depth Gauge Main Scale Inside jaws VernierScale Outside jaws
30. 30. 2. Micrometer Micrometer is one of the most widely used precision instruments. It is primarily used to measure external dimensions like diameters of shafts, thickness of parts etc.
31. 31. Different Parts of Micrometer