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Magnetic
Particle Testing |
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(Non–Destructive
Testing Training Program) |
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General |
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The complexity and expense of today's
machines, equipment, and tools dictate the use of fabrication and testing
procedures that will ensure maximum reliability. |
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Nondestructive
testing (testing without destroying) provides many of these procedures. |
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Of
the number of nondestructive test procedures available, magnetic particle
testing – of which this course is concerned – is one of the oldest and
most widely used. |
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Purpose |
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The purpose of this course is to provide
the fundamental knowledge of magnetic particle testing required by quality
assurance and test personnel to enable them to : |
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1) |
Ascertain that the proper test technique, or combination of techniques, is
used to assure the quality of the finished product |
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2) |
Interpret, evaluate, and make a sound decision as to the results of the
test |
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3) |
Recognize those areas exhibiting doubtful test results that require either
retest or assistance in interpretation and evaluation |
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Industrial
Applications Of Magnetic Particle Testing |
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Because magnetization of certain metals
is possible, small particles that are attracted to magnetic fields are
applied to the surface of the test object after or during induction of a
magnetic field, thereby detecting certain discontinuities which are
present in the material. |
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Since magnetic
particle testing is capable of revealing discontinuities (variations in
material composition) economically, it is one of the most used,
nondestructive test methods. |
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However, this test
method is limited to disclosing only those discontinuities that are at or
near the surface. |
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Testing
Philosophy |
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Nondestructive testing is used to assure
maximum reliability of machines, equipment, and tools. |
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To accomplish such
reliability, test standards have been established and test results must
meet these standards. |
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Personnel |
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It is imperative that personnel
responsible for magnetic particle testing be trained and highly qualified
with a technical understanding of the test equipment, the item under test,
and the test procedures. |
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To make optimum use
of magnetic particle testing, NDT personnel conducting tests must
continually keep abreast of new developments. There is no substitute for
knowledge. |
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Testing
Criteria |
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Modern
manufacturing procedures dictate that faulty articles be discovered as
early in the manufacturing process as possible. |
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This
means that each item must be tested individually before it is required to
perform in a subassembly and that each subassembly be tested before it is
required to perform in an assembly, etc. |
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This
building–block approach requires that test processes be selected and
test procedures be generated at the lowest level in the manufacturing
process in order that the highest reliability may be obtained with lowest
cost. |
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Test
Procedures |
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Approved procedures for magnetic
particle testing are formulated from analysis of the test specimen, review
of its past history, experience and information available concerning
discontinuities in like or similar articles. |
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It is the
responsibility of personnel conducting or checking tests to ensure that
test procedures are adequately performed, and that the test objective is
accomplished. |
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Procedures found
incorrect or inadequate must be brought to the attention of responsible
supervision for correction. |
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Test
Objective |
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1. |
The objective of magnetic particle testing is to ensure maximum
reliability by providing a means of: |
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Obtaining a visual image of an indication related to a discontinuity in or
at the surface of a material. |
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Disclosing the nature of discontinuities without impairing the material. |
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c. |
Separating acceptable and unacceptable material in accordance with
predetermined standards. |
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2. |
No test is successfully completed until an evaluation of the test results
is made. Evaluation of test procedures and results requires understanding
of the test objective as well as an understanding of the material in the
test specimen and the manufacturing processes that were involved in
producing that article. |
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For More
Informations Click Here. |
