A QUICK OVERVIEW
• The importance and necessity of metrology have greatly increased with the industrial revolution, which emphasizes the importance of metrology in industries.
• Inspection is defined as a procedure in which a part or product characteristic, for example a dimension, is examined to determine whether it conforms to the design specification. Basically, inspection is carried out to isolate and evaluate a specific design or to measure the quality attribute of a component or product.
• We know that accuracy of measurement is very important in order to manufacture a quality product. Accuracy is the degree of agreement of the measured dimension with its true magnitude. It can also be defined as the maximum amount by which the result differs from true value.
• Precision is the degree of repetitiveness of the measuring process. It is the degree of agreement of the repeated measurements of a quantity made by using the same method, under similar conditions.
• The ability of the measuring instrument to repeat the same results during the act of measurements for the same quantity is known as repeatability.
• The difference between the true value and the mean value of the set of readings on the same component is termed as an error. Error can also be defined as the difference between the indicated value and the true value of the quantity measured.
• The ratio of the change of instrument indication to the change of quantity being measured is termed as sensitivity. When successive readings of the measured quantity obtained from the measuring instrument are the same all the time, the equipment is said to be consistent.
• Range is defined as the difference between the lower and higher values that an instrument is able to measure.
• The process of validation of the measurements to ascertain whether the given physical quantity conforms to the original/national standard of measurement is known as traceability of the standard.
• Calibration is the procedure used to establish a relationship between the values of the quantities indicated by the measuring instrument and the corresponding values realized by standards under specified conditions.
• Systematic error is a type of error that deviates by a fixed amount from the true value of measurement. These types of errors are controllable in both their magnitude and direction.
• Random errors provide a measure of random deviations when measurements of a physical quantity are carried out repeatedly. These errors can be statistically evaluated, and their mean value and standard deviation can be determined.
