Quantitative quality indicators (QQIs) are often “thin steel shims with etched patterns in circular and cross shapes” that are used in a variety of inspection situations within magnetic particle testing to “demonstrate both field strength and direction within a part” (Magnaflux 2018).
Among other uses, QQIs can be utilized for performance checks of equipment and setting up magnetization parameters and multidirectional fields (Magnaflux 2018). Handling thin shim QQIs is oftentimes difficult, as maintaining their pristine condition is paramount.
For this reason, they are often coated with a slick corrosion inhibitor—this will have little or no affect on the test results, but may require a methodology for handling prior to any production testing. They can be difficult to get out of the plastic sleeves that they are often packaged in, especially when there is a slick corrosion preventive fluid on your gloves or on the actual QQI.
Then there is the problem with mishandling them and bending them and returning them back to their original configuration. This is a real concern, as they are usually used to validate the equipment and the process or technique.
A simple solution I have found is to store your QQIs in one of those weekly medication organizers (see photo). QQIs fit perfectly in them, they protect corners from damage, and you can add a little lubricant vehicle to the container to prevent corrosion.
The cost of these organizers is minimal when you consider the aggravation avoided or the replacement cost of a lost QQI. They can be found at any pharmacy or retail store that sells over-the-counter medicine.
Author
Zachary Staniewicz is currently Senior NDT Technician at Lockheed Martin Aeronautics. He is an ASNT NDT Level III in both MT and PT. (zstan3@aol.com)
Reference
Magnaflux, 2018, “QQIs,” Product Data Sheet, magnaflux.com, accessed at magnaflux.com/Files/Product-Data-Sheets/Accessories/Quantitative-Quality-Indicator-Test-Pieces_Product-Data-Sheet_English.pdf on 12 March 2019.
This article first appeared in Volume 18, No. 2 of ASNT’s The NDT Technician. Photo courtesy of Zachary Staniewicz.