CMM(Coordinate Measuring Machine) is an advanced measurement machine works for measure complex and large component. CMM is a device for measuring the physical characteristics of an object. The machine is controlled by a computer or an operator.
CMM consists of 3-axis namely X-axis, Y-axis, Z-axis. Measurement is done by the prob attached to a third moving axis. This prob could be mechanical, optical, laser or white light.
So, the machine who takes reading in 6 DOF(Degree of freedom) known as CMM.
Or Watch out this Video
Components of CMM
The 3 main component of CMM are-
Machine itself (includes its 3-axis)
Controllers & Softwares
Working Principle of CMM
CMM record X, Y, Z coordinates of the object and generate point which analysis by regression algorithm. This points are collected by Prob via direct computer control.
Main Parts of CMM
Scales & Encoders
Machine control system
This is Mitutoyo’s manual floating bridge type CMM coordinate measuring machines designed to achieve very high accuracy in a wide range of applications.The model type is CRYSTA-PLUS M is the intelligent alternative to the complex, cost-intensive measuring equipment with conventional multi-point measuring devices.
A Feeler gauge is used to measure the clearance between two parallel flat faces for example piston and cylinder. As the name suggests, feeler gauge called as to measure neither tide nor freely.
Watch the video of feeler gauge
Feeler gauges are used for measurement of clearances.
It is a tool that measures air or narrow gap widths between two surfaces in engines and machinery.
Size of Feeler gauge
Feeler gauge available in no. of the blade like 10,13,20 and 28. With a step of 0.05 and 0.10 mm.
The thickness of the blades are in fractions of mm and inches, usually ranging from 0.03 mm to 1mm.
Parts of Feeler gauge
The feeler gauge has two major parts, a body or block which acts like a protective case or shealth and a large number of blades of different thickness.
The body is the base that holds the blades together. Feeler gauges
are made entirely of steel so that they are corrosion free and the
blades do not rust easily.
In machinery and engine service, it is important to predict accurate
measurement of gaps for smooth performance and to avoid any faulty
It is extensively and mostly used for measuring the gap between an engine cylinder and piston.
When there is extra gap even after a blade is inserted then the blades of the feeler gauge can be used in various combinations as per the requirement, that is different blades having different thickness can be stacked together and used.
How to use Feeler gauge?
The working of feeler gauge is easy. The blades are kept on the
vacant gap that needs to be measured, initially one blade of standard
thickness is kept, then if there are extra gaps other blades are
adjusted and joined together and used.
Ensure that the blades can be easily pushed to and fro and are not tight nor free to move.
In order to have a problem-free measurement, the blades should be free of dirt and grease.
Simple D’Arsonval Type to Measure Current or Voltage
It essentially consists of components like a permanent
magnet, coil, hairsprings, pointer, and scale. The coil assembly is mounted on a shaft, which in turn is hinged on a hair spring.
To concentrate the magnetic fields, initially, the iron core is placed inside the coil.
The curved pole pieces are then attached to the magnet to ascertain if the torque increases as the current increases.
This means that electromagnetic energy is used to move the meter.
Volt-Ohm Milliammetersor Multimeters
The typical volt–ohm milliammeter employs switching provisions for connecting multipliers, shunt resistors, and rectifier circuits.
The current flowing through the resistor can easily be determined by switching over to the ohm-meter function, wherein the leads can be connected to the unknown resistance that causes the meter movement.
The advantage is that direct measurement is possible since the current flow indication is calibrated in terms of resistance
The vacuum tube voltmeter, popularly known as VTVM, is basically used to measure voltage.
To control the grid of the tube, proper multiplier resistors are employed through which the AC or DC input is given to the meter.
The input resistance of a VTVM is usually very high, when compared to that of a simple meter, due to high grid circuit resistance. This minimizes the loading of the signal source.
Cathode Ray Oscilloscope
A CRO is a voltage-sensitive device that is used to view, measure, and analyse waveforms.
Its advantage is that a beam of electrons with low inertia strikes the fluorescent screen, generating an image that can rapidly change with varying voltage inputs to the system.
The cathode ray tube (CRT) is the basic functional unit of CRO. The electron gun assembly comprises a heater, a cathode, a control grid, and accelerating anodes. When a cathode is heated, electrons are generated.
The accelerating anodes, which are positively charged, provide the necessary striking velocity to the emitted electron stream.
The electron beam, after gaining necessary acceleration, passes through horizontal and vertical deflection plates, which provide the basic movements in the X and Y directions.
The XY plotters generate Cartesian graphs, which are obtained by two DC inputs, in X and in the Y-axis. It consists of two self-balancing potentiometers, one to control the position of the paper and others to control the position of the pen.
In XY plotters, the output is generated by plotting one emf as a function of the other emf.
Further, the emf, which is the output signal of transducers, may be a value of displacement, force, pressure, strain, or any other parameter.
Measurement is a Natural part of everyday life. We express daily needs in size & weights, water and electricity are also metered.
A number of blood samples, active sub-stain in medicine also needs to be precise.
I think it is Impossible to describe anything without measuring it.
Room temperature, body weight, sunshine,chest width and so on..
Almost every company are concerned with Quality management in the process of Introducing their work
First, we try to understand what is Metrology!
What is Metrology?
Metrology word derived from the Greek words Metro(means Measurement) and Logy(means Science).
Metrology includes all aspects with reference to measurements, whatever their level of accuracy.
Some technical terms are difficult to understand, so the following terminology is quite helpful for further studies
Accuracy is the closeness between a test result and accepted value.
Bias is the difference between the expected value and the accepted reference value.
Calibration is the set of operations that establish under specified conditions, the relationship between values of quantities indicated by a measuring instrument or values represented by a material measure and the corresponding values realized by standards.
Drift is slow to change of a metrological characteristic of measuring instrument.
The output result from a measuring device to be magnified many times to make it more readable, called Magnification.
Precision is the closeness of agreement between independent test results obtained under stipulated conditions.
The smallest change of the measured quantity which changes the indication of a measuring instrument is called Resolution.
Traceability means a measured result can be related to references.