Use a clear adhesive tape (for example, Scotch brand 191, 471 or 600 series) to hold the QQI in place. Tape
should be applied to all four edges to insure good contact (no air gap) and prevent the particles from getting
under the QQI. Make sure the tape does not cover the area of the QQI where the indications will form.
Super glue can provide a fixed bond, although it may be later removed by soaking in acetone.
Conduct the inspection and observe the results under the appropriate lighting. Note that the QQI was
designed for the continuous method and the indications may disappear when the applied field is removed.
Also note that the QQI will not indicate background. The actual part must be examined to determine the
amount of background present.
System Effectiveness Check.
The importance of this process control step is second only to having an adequate inspection procedure. The
intent is to use a test specimen or set of specimens to assure that the system, i.e. equipment and materials,
are capable of producing an adequate magnetic particle inspection. There is no Department of Defense
standard specimen for this requirement; consequently there are a variety of ways to fulfill the requirement,
each with its own applicability. It is the responsibility of each laboratory NCOIC to establish the
effectiveness check that best suits the requirements for their laboratory. The following information is
presented to assist these individuals in this task.
To use the Ketos ring see Figure 1-9, for the system effectiveness check, first check the ring for residual
magnetism. Apply the magnetic particle bath, wait at least 60 seconds for any indications to form, then
examine the ring. If any indications are present on the outer edge, the ring must be demagnetized and the
check repeated until no indications are formed. Next, inspect the ring using the wet continuous method with
circular magnetization applied using the current listed in Table 1-4 through a one-inch diameter central
conductor. Inspect the ring to insure the minimum number of holes listed for a given amperage is visible.
Lack of this visibility may indicate a malfunctioning magnetic particle unit, a low particle concentration, or a
ring that is not in the annealed condition. The cause of the malfunction SHALL be determined and corrected
prior to performing additional magnetic particle inspections with the deficient system.