METROLOGY AND MEASUREMENT

Course objective
After completion of this course, the students will have knowledge about measuring tools, their selection and result verification. The subject also highlights importance of metrology and it’s role in achieving quality, reliability and standardization.

Course outline

1. Introduction to metrology and measurement (8 Hours)
1. Objectives and Scope of metrology,
2. General metrological terms: measured value, true value, accuracy, precision, repeatability, reproducibility, uncertainty, sensitivity, resolution, stability, calibration, verification etc.
3. Standards of measurement, units of measurement.


2. Errors in measurement (8 Hours)
1. Types of errors, random errors, systematic errors, constant errors, scale errors, reading errors, compound errors etc.
2. Output flatness, straightness, roundness, parallelism, cylindricity, perpendicularity, angularity, concentricity errors that can be usually eliminated,
3. Errors that cannot be eliminated


3. Types of measurement and measuring instruments (12 Hours)
1. Linear measurement: Steel rule, Calipers, Vernier Calipers, Micrometers, Height gauge, Slip gauge. Angular and taper measurement:
2. Protectors, Engineering square, Adjustable bevel, Bevel protectors, Dividing head, Sine bar, Sine centers, Angle gauge, Clinomometers, Autocollimators, Taper gauges.
3. Surface measurement: Spirit level, Straight edge, Surface gauge, Optical flat, Interferometer, Surface plate.
4. Measurement of screw threads and gears.
5. Comparators: mechanical, electrical, optical, pneumatic, miscellaneous measurements


4. Limits, Fits and Gauges (8 Hours)
1. Introduction,
2. Terminology,
3. Interchangeability,
4. Selective assembly systems of limits and fits:
5. Types of fits, interference, transition and clearance fits, basis of fits:
6. Hole and shaft basis system


5. Metrology of screw threads (6 Hours)
1. Introduction:
2. Screw thread terminology,
3. Classification of threads,
4. Errors in threads,
5. Effect of errors,
6. Measuring various elements of threads,
7. Application of thread gauges.


6. Gear measurement and testing (8 Hours)
1. Introduction,
2. Gear tooth terminology,
3. Involutes curve,
4. Sources of errors in manufacturing gears,
5. Gear measurement,
6. Tooth thickness measurement,
7. Tooth profile measurement,
8. Gear pitch measurement ,
9. Allowable errors in gears,
10. Composite method of gear checking,
11. General gear tests,
12. Rolling tests.


7. Measurement of surface finish (8 Hours)
1. Measuring and causes of surface roughness,
2. Surface texture,
3. Elements of surface finish,
4. Evaluating surface finish,
5. Symbols for specifying surface finish,
6. Methods of measuring surface finish,
7. Thread instrument methods,
8. Direct instrument measurements,
9. Replica method,
10. The sample length of cut-off length,
11. Analysis of surface finish


8. Machine tool metrology (8 Hours)
1. Introduction,
2. Alignment tests,
3. Flatness tests,
4. Straightness tests,
5. Acceptance tests,
6. Spindle tests.


9. Calibration and measurement (8 Hours)
1. Press gauge,
2. Proving ring,
3. Universal testing machine,
4. Atmospheric pressure,
5. Air density,
6. Dial gauge,
7. Verification of taxi meter,
8. Verification of dispensing pumps,
9. Use of sensor and gears in measuring instruments,
10. Standard rolling machine.


10. International organizations concerning metrology (6 Hours)
1. Formation, duties and responsibilities,
2. BIPM (Bureau International de Poids et Measures),
3. OIML (Organization International de Metrology Legal),
4. CGPM (Conference General de Poids et Measures),
5. IEC (International Electro-technical Commission),
6. APMP (Asia Pacific Metrology Programmed),
7. Evolution of SI System of Units Rays.

Practical (1.5 hours/week)

1. Use of measuring instruments and gauges for linear and angular measurements: slip and block gauges, micrometers, squares, precision rules, height gauge, calipers, sine bar, surface plate, protractors, levels, limit gauges, plug and ring gauges .
2. Checking of permissible errors like output flatness, straightness, roundness, parallelism, cylindricity, perpendicularity, concentricity etc.
3. Establishment of different screw thread terminologies, thread errors, use of thread gauges
4. Establishment of simple gear tooth parameters
5. Surface finish measurements
6. Acceptance tests on machine tools / equipments – straightness test, flatness test, alignment test, spindle test, trueness test etc.

References

1. Rajput,R.K., "Mechanical Measurement and Instrumentation (including Metrology and Control System)", S.K. Kataria and Sons.
2. Jain, R. K., "Engineering Metrology", Khanna Publishers
3. Considine, D.M., “Process Instruments and Controls Handbook”, McGraw-Hill, New York, Third Edition, 1985.
4. Wolf, S. and Smith, R.F.M., “Students Reference Manual for Electronic Instrumentation Laboratories”, Prentice Hall, Englewood Cliffs, New Jersy, 1990.

Evaluation Scheme
The Questions will cover all the chapters in the syllabus. The evaluation scheme will be as indicated in the table below: