Comparators are measuring instruments that determine the sizes of a workpiece by reference to a standard. Comparators play a significant role in the accuracy of dimensional manufacture. There are two major types: electrical comparators and electronic comparators. Electrical comparators convert mechanical displacement into electrical signals, while electronic comparators, more advanced, use digital or analog electronics to achieve maximum precision.
Instrumentation
Electrical comparators operate by altering a small mechanical movement effect of dimensional differences in the object under measurement into an electrical signal. This may turn into an inductive coil or some type of capacitor. In this case, the electrical property is inductance or capacitance, which is then read off on a meter or indicated on an electronic instrument. On the other hand, electronic comparators utilize highly sensitive transducers, like LVDTs or optical sensors, to measure minute variations of the workpiece. The signal is processed electronically and can be displayed digitally; these have much higher precision than electrical comparators.
Strengths
Electrical comparators are used for reasonably accurate measurements in environments where extreme accuracy is not required. They are robust, easy to use, and can be integrated into any mechanical apparatus. Electronic comparators are more accurate because they can have extremely high resolutions and measure very short lengths of variation as small as microns with no difficulty at all. Therefore, They are better suited for use in automation and find extensive use in applications requiring high-speed measurement with very stringent quality monitoring, like in the automobile and aircraft industries.
Limitations
While practical for rough measurements with unsophisticated dimensions, electrical comparators are not too sensitive and are prone to contamination by mechanical wear, temperature fluctuations, and environmental interference. Even so, they respond after longer times than electronic comparators. Electronic comparators, as precise devices, are expensive and complicated. Moreover, they require sophisticated maintenance and calibration for accuracy. Additionally, they can easily be susceptible to electrical noise or power fluctuation and may not work efficiently in some environments.
Related Techniques to Electrical Comparators and Electronic Comparators
Optical comparators and coordinate measuring machines offer an additional way of checking accuracy in terms of dimension. In automation manufacturing processes, laser-based measuring systems are used with digital micrometers in tandem with comparators for even higher precision levels and the flexibility to measure almost any object.
