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Applications
Below you will find a general
outline of the capabilities of some common nondestructive testing methods. This is intended
as brief summary of each discipline's capabilities.
We have about 60 years of combined
NDT experience at JWJ and with those years, we have seen and solved scores of difficult
applications. If you have and questions about your application, please email sales@jwjndt.com or call us.
This service is of no charge to you.
ULTRASONICS
Measures thickness,
velocity, or
detects internal defects and variations, such as cracks, lack of fusion,
delaminations,
lack of bond.
Applications include, wrought
metals, welds, brazed joints, adhesive or bonded joints, non-metallic materials,
in-service parts.
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Advantages
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Disadvantages
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Most sensitive to
cracks
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Couplant required |
| Immediate results |
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Complex, or small
parts may be difficult to check |
| Automation possible |
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Reference standards
required |
| Permanent record
capability |
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Trained operators for
manual inspections |
| Portable |
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Special Probes |
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High penetration
capability
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Surface condition
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EDDY CURRENT
Measures or detects surface and
subsurface cracks and seams, alloy content, heat treatment variations, wall and coating
thickness, crack depth, conductivity, and permeability.
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Advantages
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Disadvantages
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High speed
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Conductive material only
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Low cost
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Shallow depth of penetration
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Automation possible
for symmetrical parts
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Reference standards required
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Permanent record
capability
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No couplant required
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No probe contact
required
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RESONANT
INSPECTION
Detects
resonant frequency shifts resulting from changes in mass, stiffness or
damping of a part. Defects such
as cracks, voids, chips, brazing problems, nodularity, porosity, variations
in hardness, missed manufacturing processes, and delamination can be
detected.
Applications
include powder metal parts, ductile iron parts, brazed assemblies, forgings,
stampings, and ceramic parts.
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Advantages
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Disadvantages
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Whole part test for
internal and external flaws
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Not diagnostic – does not
indicate where flaw is, just there is one
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Fast as 1 part per second
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Materials that resonate
only - metal, composites and ceramic parts
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No part preparation
required
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Large parts (> 60lbs)
difficult to test
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Objective pass/fail resu
lt
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Significant lot to lot
variations can “mask” defect detection
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No consumables expenses
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Easily automated
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Permanent record capability
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Easily finds first n
number of natural frequencies for NVH applications
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Best for high volume
quality inspection
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Designed to be on the plant
floor
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RADIOGRAPHY
Measures or detects, internal
defects and variations, porosity, inclusions, cracks, lack of fusion, corrosion, geometry
variation, density changes, misassembled, and misaligned.
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Advantages
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Disadvantages
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Permanent records
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Radiation hazard
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Portable
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Expensive
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Geometry variation do
not effect direction of radiation
beam
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Trained operators
needed
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Linear defect may be
missed
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Depth of defect not
indicated
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Access needed to at
least two sides of the part
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LIQUID
PENETRANT
Measures or detects defects open to
the surface of parts such as cracks, porosity, seams, laps, through wall leaks.
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Advantages
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Disadvantages
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Low cost
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Defect must be open to the surface
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Portable
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Parts must be cleaned before and
after testing
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Indications may be
further examined
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Surface films, such as coatings,
scale, and smeared metal visually may mask defects
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MAGNETIC
PARTICLE
Measures or detects surface and
qualified subsurface defects, cracks, seams, porosity, inclusions, and very sensitive for
locating small tight cracks.
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Advantages
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Disadvantages
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Low cost
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Ferromagnetic materials only
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Portable
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Alignment of magnetic field is
critical
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Subsurface defects
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Demagnetization required after the
test
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Surface coatings can mask defects
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Pre and post cleaning necessary
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Messy
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INFRARED THERMOGRAPHY
Measures or detects, hot spots,
heat transfer, temperature ranges, temperature monitoring, and electrical assemblies.
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Advantages
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Disadvantages
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Permanent record or
thermal picture
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Expensive
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Remote sensing
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Reference standards required
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Portable
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Poor resolution on thick sections
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last updated April 06, 2009
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