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Non-Destructive Testing (NDT) is the process of inspecting, testing, or evaluating materials without destroying the serviceability of the part

Visual inspection inspect for high splatter, undercut, bad stop start point, surface crack.

Surface inspection
– Magnetic particle
– Liquid dye penetrant

Internal inspection

Radiography
Ultrasonic

Most frequently used test methods

Magnetic particle

– Testing magnetic fields to locate surface discontinuities in magnetic materials. When the magnetic field encounters a discontinuity, the flux lines produce a magnetic flux leakage
Because magnetic flux lines don’t travel well in air, magnetic particles are applied to the surface of the part the particles will be drawn into the discontinuity, use of a Yoke to generate magnetic field

Liquid dye penetrant test

Penetrant is applied to the surface of a part, it will penetrate into cracks. Once the excess penetrant is removed, the penetrant trapped in those voids creating an indication. They can be seen in ambient light, or fluorescent, if use of fluorescent liquid penetrant
Consist of clean, penetrant and developer.

Radiographic method
Exposing a test object to penetrating radiation so that the radiation passes through the object being inspected and a recording medium placed against the opposite side of that object. With both, the radiation passing through the test object. causing an end effect of having darker areas where more radiation has passed through the part and lighter areas where less radiation has penetrated. Use of x-ray or gamma ray

4) Ultrasonic method

Ultra-high frequency sound is injected into the part being inspected and if the sound hits a material with cracks, discontinuity
Some of the sound will reflect back to the sending unit and can be presented on a visual display. 
By knowing the speed of the sound through the part and the time required for the sound to return to the sending unit, differences shows place of crack. Thus able to find likely area of discontinuity by the darker area

• This topic was modified 4 years, 10 months ago by Admin.
• This topic was modified 4 years, 5 months ago by Admin.
• This topic was modified 4 years, 5 months ago by Admin.
• This topic was modified 4 years, 5 months ago by Admin.

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