General Description:
7HF is an oil based ready to use black ink for wet method magnetic particle testing.The ink is used in conjunction with suitable magnetising equipment to locate fine surface and slightly subsurface discontinuities in ferrous materials.
Typical defects found include shrink cracks, welding defects, grinding cracks, quenching cracks and fatigue cracks. 7HF gives clear black indications when viewed in daylight.
Composition:
7HF consists of a suspension of magnetic particles in a high flash petroleum distillate.
Method of Application:
Aerosol spray is the only possible method of application. First, make sure that the inspected surfaces are clean and dry. For permanently magnetized parts, shake can until agitator rattles; cover surface with spray. When using the continuous magnetizing method, fix the part in the magnetizing unit, cover the surface quickly with 7HF Black spray, and immediately magnetize the part.
Clean Up:
Demagnetize the part, and wipe clean with rags dampened with either water or solvent. Complete removal of 7HF magnetic particle materials will be impossible if the part is not demagnetized.