Enhancing the penetrant test Strike the part to force the liquid out of the defect Fluorescent-penetant depth of surface defects may be correlated with the richness of color and speed of bleed out Filtered-particle inspection This method depends on the unequal absorption into a porous surface of a liquid containing fine particles in suspension Preferential absorption causes the fine particles in the solution to be filtered out and concentrated directly over the crack, producing a visual indication Cracks on Non-conducting materials -a cloud of fine electrically charged particle is blown over the surface causing a buildup of powder at the defect 202128 & Dr Jonathan c.Y. Chung: NDE
Enhancing the penetrant test ◼ Strike the part to force the liquid out of the defect ◼ Fluorescent-penetant depth of surface defects may be correlated with the richness of color and speed of bleed out ◼ Filtered-particle inspection: -This method depends on the unequal absorption into a porous surface of a liquid containing fine particles in suspension. -Preferential absorption causes the fine particles in the solution to be filtered out and concentrated directly over the crack, producing a visual indication. ◼ Cracks on Non-conducting materials: -A cloud of fine electrically charged particle is blown over the surface, causing a buildup of powder at the defect. ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖11
Magnetic Particle Test Use to locate the defects at or near the surface of ferromagnetic objects. The magnetic particles tends to pile up and bridge over discontinuities a surface crack is indicated by a line of the fine particle following the outline of the crack A subsurface defect by a fuzzy collection of the fine particles on the surface near the defect Fatigue crack in an airplane gear Orientation of cracks Some cracks are more difficult to detect DC current is often employed, since it permit deeper defects detection 202128 & Dr Jonathan c.Y. Chung: NDE
Magnetic Particle Test ◼ Use to locate the defects at or near the surface of ferromagnetic objects. ◼ The magnetic particles tends to pile up and bridge over discontinuities. ◼ A surface crack is indicated by a line of the fine particle following the outline of the crack. ◼ A subsurface defect by a fuzzy collection of the fine particles on the surface near the defect. ◼ Fatigue crack in an airplane gear. ◼ Orientation of cracks ◼ Some cracks are more difficult to detect. ◼ DC current is often employed, since it permit deeper defects detection. ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖12
Permanent magnets withr Soft iron keepers Two Bar Magnets with Keeper s and Cardboard Divider Card board Crescent Magnet 黑 20 soft iron Keepers
Permanent magnets with soft iron keepers ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖13
Fixture for yoke indudtrun of longitudinal magnetic field Flexible Yoke Transverse Crack Longitudinal Flu =二二二 202128 Yoke Magnetization
Fixture for yoke induction of longitudinal magnetic field ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖14
Leakage flux Localized Leakage Field Mognetic Poles SAN Nort h South Pole Pole 202128 & Dr Jonathan c.y. Chung: NDE 今15
Leakage Flux ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖15