INSPECTION OF
CASTINGS
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SEVERAL METHODS
VISUAL
OPTICAL
- FOR SURFACE DEFECTS
SUBSURFACE AND INTERNAL DEFECTS
THROUGH NDTs & DTs
PRESSURE TIGHTNESS OF VALVES BY
SEALING THE OPENING AND
PRESSURISING WITH WATER
CASTING DEFECTS
SURFACE
METALLIC PROJECTION (4)
DEFECTIVE SURFACE (11)
CHANGE IN DIMENSION- WARP
INCOMPLETE CASTING
MISRUN, RUNOUT
CAVITYBLOWHOLES, SHRINKAGE
PINHOLES
DISCONTINUITY
HOT CRACK
COLD SHUT, COLD CRACK
SUBSURFACE
SUBSURFACE CAVITY
INCLUSIONS
DISCONTINUITY
NDTs
Methods of testing
DestructiveNon destructiveRadiagraphic
Ultrasonic
Non Destructive Testing
with Ultrasonics
for flaw Detection in Castings,
Weldments, Rails, Forged Components etc.
ULTRASONIC TESTING
Why Ultrasonics ?
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Flaw detection in metals and nonmetals
Flaw measurement in very thick materials
Internal and surface flaws can be detected
Inspection costs are relatively low.
Rapid testing capabilities and portability.
Ultrasonic waves are simply vibrational waves
having a frequency higher than the hearing range
of the normal human ear, which is typically
considered to be 20,000 cycles per second (Hz).
The upper end of the range is not well defined.
Frequencies higher than 10 GHz have been
generated. However, most practical ultrasonic
flaw detection is accomplished with frequencies
from 200 kHz to 20 MHz, with 50 MHz used in
material property investigations. Ultrasonic
energy can be used in materials and structures
for flaw detection and material property
determinations.
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Ultrasonic waves are mechanical waves
(in contrast to, for example, light or xrays, which are electromagnetic waves)
that consist of oscillations or vibrations
of the atomic or molecular particles of a
substance
about
the
equilibrium
positions of these particles. Ultrasonic
waves behave essentially the same as
audible sound waves. They can
propagate in an elastic medium, which
can be solid, liquid, or gaseous, but not
in a vacuum.
In solids, the particles can (a) oscillate along the direction of sound
propagation as longitudinal waves, or (b) the oscillations can be
perpendicular to the direction of sound waves as transverse
waves. At surfaces and interfaces, various types of elliptical or
complex vibrations of the particles occur.
THEORY OF TESTING
MACHINE SPECIFICATIONS
Make:
Weight:
Calibration range upto 9999 mm.
Choice of Frequency range
Provision for adjusting gain.
Documentation possibility via printer
Limitation:…………….
Probe
SCANNING TECHNIQUES
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Pulse Echo method
Straight beam method
Angle beam method
PULSE ECHO METHOD
Inspection of:
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Gas porosity
Slag Entrapment
Cracks
With the exception of single gas pores all the
defects listed are usually well detectable by
ultrasonics.
Ultrasonic flaw detection has long been the
preferred method for nondestructive testing ,
mainly in welding applications.
This safe, accurate and simple technique has
pushed ultrasonics to the forefront of inspection
technology.
The proper scanning area for the weld:
First calculate the location of the sound
beam in the test material.
Using the refracted angle, beam index point
and material thickness, the V-path and skip
distance of the sound beam is found.
Then identify the transducer locations on the
surface of the material corresponding to the
crown, sidewall, and root of the weld.
Inspectionof Rails
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New trend:
Ultrasonic Simulation - UTSIM
UTSIM is a user interface integrating
a CAD model representing a part
under inspection and an
ultrasound beam model.
Ultrasonic sizing of small flaws with
the distance-amplitude-correction (dac) curve