Basic units - system concepts used in measuring technology - measuring instruments - length, angles and surface - scope of metrology
MEANING OF METROLOGY
Metrology is the science of measurement
Metrology may be divided depending upon the quantity to be measured like metrology of length, metrology of time.But for engineering purposes, it is restricted to measurement of length and angles and other qualities which are expressed in linear or angular terms.
In the broader sense it is not limited to length measurement but it is also concerned with industrial inspection and its various techniques.
Metrology is mainly concerned with:
(1) Establishing the units of measurements, ensuring the uniformity of measurements.
(2) Developing methods of measurement.
(3) Errors of measurement.
(4) Accuracy of measuring instruments and their care.
(5) Industrial inspection and its various techniques.
OBJECTIVES OF METROLOGY
The basic objective of a measurement is to provide the required accuracy at a minimum cost.
- Complete evaluation of newly developed products.
- Determination of Process Capabilities.
- Determination of the measuring instrument capabilities and ensure that they are quite sufficient for their respective measurements.
- Minimizing the cost of inspection by effective and efficient use of available facilities
- Reducing the cost of rejects and rework through application of statistical quality control techniques.
- To standardize the measuring methods.
- To maintain the accuracies of measurement.
- To prepare design for all gauges and special inspection fixtures.
PROCESS OF MEASUREMENT
The sequence of operations necessary for the execution of measurement is called process of measurement.
There are main three important elements of measurement,
- Measurand
- Reference
- Comparator
(1) Measurand:
- Measurand is the physical quantity or property like length, angle, diameter, thickness etc. to be measured.
(2) Reference:
- It is the physical quantity or property to which quantitative comparisons are made.
(3) Comparator:
- It is the means of comparing measuring measurand with some reference.
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