Parker Research Notch Defect Test Bar
NA-16 Notch Defect Test Bar allows the user the opportunity to detect small surface defects. This ensures that the user's magnetic particle equipment and consumables are up to standard and being used properly.
The NA-16 Notch Test Bar complies with the requirements of old MIL-STD-271 E and F (ships) paragraph 126.96.36.199 and NAVSEA-TB-T9074-AS-GIB-101-271. The requirement reads as follows:
188.8.131.52 Procedure: Magnetic particle inspection shall be performed in accordance with a written procedure which has proven ability to detect the smallest rejectable surface dects, artificial or natural, in a test spectrum.
The yoke and prod methods shall have the proven ability to detect a 1/16-inch long by 0.006-inch wide by 0.02-inch deep notch (maxmimum dimensions) oriented 90° to the magnetic flux. The notch shall be cut in a ⅜-inch low alloy metal steel plate and it shall be filled flush to the surfaces with a non-conducting material, such as epoxy, to prevent the mechanical holding of the indicating medium.
Each activity shall certifiy the prodedure in accordance with this standard, and upon request by the Government inspector, shall make the prodedure available and demonstrate its validity by performing inspection on the test specimen.
Place the yoke or prods upon the test side of the NA-16 test bar, indicated by the unpainted circle. Energize the magnetic field and apply the inspection medium
The test defects as described above are located within the circle. One notch is oriented 90° to the bar parallel for yoke tests. The second notch is located longitudinally with the bar parallel for prod tests.
NOTE: Unless specified otherwise, tests should be performed with the yoke or prods in AC mode. Furthermore, if prods are used it may be necessary to remove paint from the test bar at contact points.