• Condition monitoring (CM) is a process of monitoring a
parameter of condition in machinery eg . Vibration ,
• In order to identify a significant change which is indicative of
developing a fault .
• Condition monitoring is a process which is used to monitor the
condition of the machine which ultimately reduces the time
required to identify and rectify the fault which further
increases the efficiency of the machine.
• Condition monitoring provides us the real time information
about the condition of the machine which gives us the ability
to minimize or to eliminate the factors responsible for
occurrence of faults .
Vibration condition monitoring
• Machine vibrations, also called chatter, correspond to the relative
movement between the work piece and the cutting tool. The
vibrations result in waves on the machine surface. This affects
typical machining processes, such as turning , milling , drilling,
Accelerometers are transducers for measuring the dynamic
acceleration of a physical device. The most common accelerometer
measures acceleration only along a single axis. This type is often used
to measure mechanical vibration levels. The second type is the triaxial
accelerometer. This accelerometer is used to determine the type of
vibration or the direction of acceleration.
Accelerometers designed to measure vibration are based on the
piezoelectric effect. In a piezoelectric accelerometer, a mass
applies force to a crystal creating a high-impedance charge,
which results in a voltage across the crystal.
Piezoelectric accelerometers require an external amplifier to
amplify the charge easier to use accelerometers recommended
for typical measurements include an integrated amplifier. These
sensors are referred to as integrated electronic piezoelectric
• Oil analysis (OA) is the laboratory analysis of a lubricant's
properties, suspended contaminants, and wear debris. OA is
performed during routine preventive maintenance to provide
meaningful and accurate information on lubricant and
machine condition. By tracking oil analysis sample results over
the life of a particular machine, trends can be established
which can help eliminate costly repairs.
OA can be divided into three categories:
• analysis of oil properties including those of the base oil and its
• analysis of contaminants,
• analysis of wear debris from machinery,
• Acoustic emission (AE) is the phenomenon of radiation of acoustic
(elastic) waves in solids that occurs when a material undergoes
irreversible changes in its internal structure, for example as a result
of crack formation or plastic deformation due to aging, temperature
gradients or external mechanical forces.
• In particular, AE is occurring during the processes of mechanical
loading of materials and structures accompanied by structural
changes that generate local sources of elastic waves. This results in
small surface displacements of a material produced by elastic
or stress waves generated when the accumulated elastic energy in a
material or on its surface is released rapidly.
• The waves generated by sources of AE are of practical interest in
methods used to capture AE in a controlled fashion, for study and/or
use for inspection of structural integrity, quality control, system
feedback, process monitoring, and others.
How to use AE
• The application of acoustic emission to non-destructive testing of materials,
typically takes place between 100 kHz and 1 MHz Unlike conventional ultrasonic
testing, AE tools are designed for monitoring acoustic emissions produced within
the material during failure or stress.
• To study the formation of cracks during the welding process, as opposed to
locating them after the weld has been formed.
• In a material under active stress, such as some components of an airplane
during flight, transducers mounted in an area can detect the formation of a crack
at the moment it begins propagating.
• A group of transducers can be used to record signals, then locate the precise
area of their origin by measuring the time for the sound to reach different
• The technique is also valuable for detecting cracks forming in pressure
vessels and pipelines transporting liquids under high pressures. Also, this
technique is used for estimation of corrosion in reinforced concrete structures
Thermal images, are actually visual displays of the amount of
infrared energy emitted, transmitted, and reflected by an object.
The image shows the viewer an approximation of the
temperature at which the object is operating, the camera is
actually using multiple sources of data based on the areas
surrounding the object to determine that value rather than
detecting the actual temperature.
This phenomenon may become clearer upon consideration of
Incident Energy = Emitted Energy + Transmitted Energy +
• Incident Energy is the energy profile when viewed through a
thermal imaging camera.
• Emitted Energy is generally what is intended to be measured.
• Transmitted Energy is the energy that passes through the
subject from a remote thermal source.
• Reflected Energy is the amount of energy that reflects off the
surface of the object from a remote thermal source.
• If the object is radiating at a higher temperature than its
surroundings, then power transfer will be taking place and
power will be radiating from warm to cold.
• We can use thermal imaging camera to take the picture of the
object and it will build a picture in the viewer and record a
visible picture, usually in a JPG format.
• This functionality makes the thermal imaging camera an
excellent tool for the maintenance of electrical and
mechanical systems in industry and commerce. By using the
proper camera settings and by being careful when capturing
the image, electrical systems can be scanned and problems
can be found
Ultra Sound Emission
Ultrasound transducers are used to convert an electrical signal
into ultrasonic energy that can be transmitted into the object to be
monitored, and to convert ultrasonic energy reflected back from
the object into an electrical signal.
The general composition of an ultrasound transducer is shown
• the most important component is a thin piezoelectric (crystal)
element located near the face of the transducer
• the front and back face of the element is coated with a thin
conducting film to ensure good contact with the two electrodes
• the outside electrode is grounded to protect the patient from
• an insulated cover is used to make the device watertight
• an acoustic insulator made of cork or rubber is used to prevent
the passing of sound into the housing (i.e. reduces transducer
• the inside electrode is against a thick backing block that absorbs
sound waves transmitted back into the transducer
How to create an ultrasoundwaveusing
• When a positive voltage is applied across the surface of the
crystal, it creates an electric field across the crystal surface
which cause the molecules (dipoles) in the crystal to realign
and thus changing the shape (width) of the crystal.
• When the voltage polarity is changed from positive to negative,
there is a point in time when the electric field across the crystal
is zero (at voltage equal to zero) and the crystal relaxes .
When the voltage polarity is reversed (i.e.: negative) the crystal
realigns once again and changes its width once again .
• The net effect the alternating voltage pulse has on the crystal
is to make it oscillate back and forth about its width. This
change in shape of the crystal increases and decreases the
pressure in front of the transducer, thus producing ultrasound