It is the process of testing an equipment by testing the instrument with a calibration standard to ensure that the equipment’s obtained measurement values are in accordance with the calibration standards.
In simple words, if any instrument is used to measure a product or object and see its result, the data of the result should be according to the calibration standard. Only then will the accuracy of the instrument be known, which must be as per acceptable standards.
Good measurement depends on the integrity of the measuring instruments used. Unfortunately, no matter how sophisticated a measurement device is, it tends to wear out over time due to thermal, mechanical, electrical, and environmental effects. This degradation is called drift, and it is inevitable.
Basic vocabulary – Usual for Calibration process
- Accuracy – how close the measurement is to the ‘true’ value of the parameter being measured.
- Precision – how repetitive or closely grouped are the measurement readings.
- Resolution – the level of discrimination that the measuring instrument can show; smallest unit change that it can sense or detect.
- Sensitivity – the smallest change in the input (stimulus) that causes a perceptible change in the output.
- Stability – the tendency of a measuring instrument not to ‘drift’ or degrade over time and use.
However, the effect of drift on the reliability of a measurement can be offset by a process called calibration.
Calibration is simply the comparison of the performance of a measuring instrument or device to a reference standards of known accuracy. In addition to this determination and reporting of deviations from the nominal, it may also include correction (adjustment) to reduce errors.
Example
If a steel pipe production manufacturer wants to calibrate its gauge.
The quality department will make a program for calibration of all gauges available with them.
Suppose a quality engineer wants to calibrate a gauge – in house of ABD.
The first quality engineer – taking any masterpiece pipe for testing – will measure the outside diameter, inside diameter of that pipe.
Another quality engineer will measure the same masterpiece pipe with the same gauge.
The same process will be repeated by the third engineer.
The data from all three quality engineers are then cross-checked and compared with the true measurement of the masterpiece – against the calibration standard – to determine the actual difference.
The gauge is considered measurable if the data obtained from the quality engineers tallies with the true measurement of the masterpiece, or meets acceptable standards, otherwise not.
Properly calibrated equipment assures that the company’s products and services meet customer specifications worldwide. In the semiconductor industry, all critical equipment used in manufacturing has to undergo periodic calibration.
How often is calibration needed?
The first question usually related to calibration and alignment is “How often do I need to do this?”.
There’s no set answer to this that I’m aware of, you’ll have to use common sense. Your amount of use, your surroundings, and especially if you travel with your devices will help determine when you should recalibrate.
If it’s a question of whether you bumped into the probe or the camera, double check. If you travel with an arm, recline. Once you get use to the process of calibration it doesn’t take very long to complete. I myself try to recalibrate every two to three weeks, that way I am confident that the data I collect is accurate.
What is the principle of calibration?
How accurately does the tool currently in use work? The basic principle is to measure the accuracy of the instrument to be measure by a “measuring instrument” to ascertain it and compare it to a known standards or reference.
Why applies this principle? because over time anything gets lost in its precision due to environmental or other reasons, which creates a gap in the actual measurement number.
See, the principle of calibration is important to ensure that measurements are complete with an instrument are accurate and reliable. Without calibration, there is a risk that the measurements made with the instrument will be incorrect.
Types of calibration
There are a total of eight types of calibration, but the type of calibration to be perform depends on the “nature of the instrument or system” being calibrate and the requirements of the “application”.
Here are some of the most common types of calibration:
| NO. | TYPE OF CALIBRATION | EXAMPLE INSTRUMENT NAME |
|---|---|---|
| 01 | Electrical calibration. | Voltage meters, Current meters, Oscilloscopes, Frequency generators, Insulation testers etc… |
| 02 | Temperature calibration. | Thermometers, Thermocouples, Temperature controllers, Furnaces, etc.. |
| 03 | Pressure Calibration | Pressure gauges, Pressure transmitters, Pressure switches, Transducers, Test Gauges, Barometers etc.. |
| 04 | Flow Calibration | Flow meters, Flow controllers, Turbine Meters, etc.. |
| 05 | Mechanical calibration | Torque wrenches, Force gauges, Hardness testers, Micrometers, Verniers, etc.. |
| 06 | Optical Calibration | Spectrometers, Photometers, Laser distance meters, etc.. |
| 07 | Sound calibration | Sound level meters, Acoustic analyzers, etc… |
| 08 | Radiation Calibration | Geiger counters, Dosimeters, Radiation detectors etc… |
The types list above are common types, with calibrations apart, applicable to a wide range of instruments and systems. These procedures include functional testing, calibration verification, and adjustment or adjustment.