June 2021

A piezoelectric sensor is a device that uses the piezoelectric effect to measure pressure, acceleration, strain or force. When pressure, force or acceleration is applied to piezoelectric materials such as quartz crystal, PZT ceramic, tourmaline, gallium phosphate, and lithium sulfate, an electrical charge is developed across the crystal that is proportional to the force applied

The bourdon tube pressure sensor instrument is one of the oldest pressure sensing instruments in use today. It is widely used in applications where inexpensive static pressure measurements are needed. The bourdon tube consists of a thin-walled C-shaped tube that is flattened diametrically on opposite sides to produce a cross-sectional area elliptical in shape, having

The bellows pressure sensor is a one-piece, collapsible, seamless metallic unit that has deep folds formed from very thin-walled tubing. It looks like a stake of capsules. It is more sensitive than the diaphragm and capsule pressure sensors. The diameter of the bellows ranges from 1.2 to 30 cm and may have as many as

In order to improve the sensitivity, two corrugated diaphragms are combined by arranging these in back-to-back and sealed together at the periphery to obtain shell-like shape as shown in fig(capsule pressure sensor) . These are called as capsules. One of the diaphragms is provided with a central reinforced port to allow the pressure to be

The diaphragm pressure sensor uses the elastic deformation of a diaphragm (i.e. membrane) to measure the difference between an unknown pressure and a reference pressure. Diaphragm is a thin circular elastic membrane made of generally silicon as show in fig. As pressure changed, the diaphragm moves, and. this motion is the measure of differential pressure.

This is an example for absorption type hydraulic dynamometer. Principle: When a conducting material moves through a magnetic flux field, voltage is generated, which causes current to flow. If the conductor is a wire forming, a part of a complete circuit current will be caused to flow through that circuit, and with some form of

Measuring the strain induced in a shaft due to an applied torque has been the most common method used for torque measurement in recent years. Torque transducers based on strain measurement are normally made by applying strain gauges to a shaft to measure the shear strain caused by torsion. The shear stress causes strains to

The main features of CNC – CMM are shown in fig. The stationary granite measuring table, length measuring system, air bearings, control unit and software are the important parts of CNC and CMM. Stationary granite measuring table Granite table provides a stable reference plane for locating parts to be measured. It is provided with a

The below fig shows the layout of a computer controlled CMM, a flexible measuring centre. The measurements, inspection of parts for dimension form, surface characteristics and position of geometrical elements are done at the same time. Mechanical systems for the computer controlled CMM can be subdivided into four basic types. The selection of a particular

The optical setup for the X-axis calibration is shown in fig below. In this fig the laser head is mounted on the tripod stand and its height is adjusted corresponding to the working table of CMM. The interferometer contains a polarized beam splitter which reflects F1 component of the laser beam. Now, let the F2