Magnaflux® Nickel Chrome-Plated Test Pieces are ideal penetrant sensitivity comparators and come in four types: flaw depths of 50μ, 30μ, 20μ and 10μ. These panels allow ‘‘in use’’ penetrants to be compared against fresh ‘‘unused’’ penetrant to determine if the product is performing properly. For visible (Type II) penetrant, panels with 30μ and 50μ depths are typically used. Fluorescent (Type I) penetrant can be used with any flaw depth.
The panels are made by plating a brass plate with nickel to a desired thickness (10μ, 20μ, 30μ, 50μ). Tension is then applied to the panels to create linear, fine cracks. A crack created over the plate layer stops at the boundary surface with the brass plate, thus the crack depth becomes equal to the thickness of the plated layer. The plates are then divided in half with a very thin layer of chrome as a protection film. The flaw pattern on the two pieces is highly symmetrical. This feature makes it possible to make side by side comparisons.