Podcast
Questions and Answers
What is a common requirement for all types of penetrants?
What is a common requirement for all types of penetrants?
- The surface of the component to be heated before application
- The surface of the component to be cooled before application
- The surface of the component to be perfectly clean and free of oil, grease and other contaminants (correct)
- The surface of the component to be roughened before application
What is the purpose of an emulsifier in post-emulsifying penetrant?
What is the purpose of an emulsifier in post-emulsifying penetrant?
- To control the amount of penetrant removed (correct)
- To mix with the penetrant before application
- To remove the penetrant from the surface
- To treat the surface before applying the penetrant
How is a solvent-removable penetrant typically removed?
How is a solvent-removable penetrant typically removed?
- By submerging the part in a solvent
- By using a towel with a solvent applied to it (correct)
- By using compressed air
- By spraying a solvent directly onto the surface
What is the purpose of a developer in the liquid penetrant process?
What is the purpose of a developer in the liquid penetrant process?
What is the benefit of using a non-aqueous developer?
What is the benefit of using a non-aqueous developer?
What type of light is used to visualize fluorescent dye?
What type of light is used to visualize fluorescent dye?
What is the primary material requirement for using magnetic particle inspection?
What is the primary material requirement for using magnetic particle inspection?
What causes the creation of an additional pair of magnetic poles in magnetic particle inspection?
What causes the creation of an additional pair of magnetic poles in magnetic particle inspection?
What is the purpose of magnetising the part being tested in magnetic particle inspection?
What is the purpose of magnetising the part being tested in magnetic particle inspection?
What is required to achieve effective magnetic particle inspection?
What is required to achieve effective magnetic particle inspection?
What is a critical factor in selecting an NDI technique?
What is a critical factor in selecting an NDI technique?
What is the desired orientation of the magnetic field in relation to the crack?
What is the desired orientation of the magnetic field in relation to the crack?
What is used to magnetise the part under test in magnetic particle inspection?
What is used to magnetise the part under test in magnetic particle inspection?
What is the primary purpose of a visual inspection in NDI?
What is the primary purpose of a visual inspection in NDI?
What can enhance the visual inspection procedure?
What can enhance the visual inspection procedure?
What can be used to assist with visual inspections?
What can be used to assist with visual inspections?
What can be quickly determined by viewing 'shine' or 'shadow' during a visual inspection?
What can be quickly determined by viewing 'shine' or 'shadow' during a visual inspection?
What is affected by the maximum acceptable defect size and distribution?
What is affected by the maximum acceptable defect size and distribution?
What type of materials can be inspected using ultrasonic inspection?
What type of materials can be inspected using ultrasonic inspection?
What is the purpose of the coupling medium in ultrasonic testing?
What is the purpose of the coupling medium in ultrasonic testing?
What happens to the ultrasonic wave when it strikes an interrupting object?
What happens to the ultrasonic wave when it strikes an interrupting object?
What is the function of the transducer element?
What is the function of the transducer element?
What type of display is used to show the ultrasonic signals?
What type of display is used to show the ultrasonic signals?
What is the direction in which the high-frequency sound wave can be introduced into the part under test?
What is the direction in which the high-frequency sound wave can be introduced into the part under test?
How does the operator evaluate the indications in ultrasonic inspection?
How does the operator evaluate the indications in ultrasonic inspection?
What is the purpose of reference standards in ultrasonic inspection?
What is the purpose of reference standards in ultrasonic inspection?
In through-transmission ultrasonic inspection, how many transducers are used?
In through-transmission ultrasonic inspection, how many transducers are used?
What is the result of the signal loss measurement in through-transmission ultrasonic inspection?
What is the result of the signal loss measurement in through-transmission ultrasonic inspection?
What is the purpose of radiography in NDI?
What is the purpose of radiography in NDI?
How does radiography work?
How does radiography work?
Study Notes
Factors Affecting Inspection
- Critical nature of the component affects inspection
- Material, size, shape, and weight of the part influence inspection
- Type of defect sought and maximum acceptable defect size and distribution are key factors
- Part accessibility or portability and number of parts to be inspected also impact inspection
- Degree of inspection sensitivity required is an important factor in selecting an NDI technique
Visual Inspection
- Most common form of NDI
- Enhanced by using appropriate combinations of light sources, magnifying instruments, and mirrors
- Borescopes and video scanners are additional tools used to assist with visual inspections
- Cracks can be quickly determined by viewing ‘shine’ or ‘shadow’
Liquid Penetrant Process
- Three types of penetrant are used: water-soluble, post-emulsifying, and solvent-removable
- Surface of the component must be perfectly clean and free of oil, grease, and contaminants
- Water-soluble penetrants are the easiest to remove
- Post-emulsifying penetrants must be treated with an emulsifier before washing
- Solvent-removable penetrants require a solvent to remove
Developers
- Two types of developer: fluorescent and coloured
- Fluorescent dye is visible in the presence of ultraviolet light
- Coloured dye shows up as a red line on the white developer background
- Wet developer is a white powder mixed with water
- Non-aqueous developer uses a solvent instead of water for rapid drying
Magnetic Particle Inspection
- Only usable on parts made using ferrous material
- Principle of operation is based on magnetic theory
- Crack in the material creates an additional pair of magnetic poles
- Magnetic particle inspection is useful for detecting cracks, splits, seams, and voids
Achieving Correct Magnetic Orientation
- Orientation of the magnetic field must be perpendicular to that of the crack
- Magnetising force is achieved by using an electric current
Ultrasonic Inspection
- Suitable method for detecting internal delamination, voids, or inconsistencies in composite components
- High-frequency sound wave is introduced into the part under test
- Ultrasonic energy does not travel through air, requiring a couplant
- Introduced sound is monitored for any significant change as it travels through the part
Through-Transmission Ultrasonic Inspection
- Uses two transducers, one on each side of the area to be inspected
- Ultrasonic signal is transmitted from one transducer and received by the other
- Loss of signal strength is measured by the instrument
- Signal loss is compared to a reference standard, and areas with a greater loss are considered defective
Pulse Echo Ultrasonic Inspection
- Single-side ultrasonic inspection using pulse echo techniques
- Single search unit works as a transmitting and receiving transducer
Radiography
- Allows a view into the interior of the part
- Accomplished by passing X-rays through the part or assembly being tested
- Rays that are not absorbed are recorded onto a film sensitive to X-rays
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