A new article by Laboratory Testing Inc.’s NDT Manager, Rich Goodwin, is spotlighted in the October 2014 issue of Quality Magazine. This article, titled “Choose the Most Reliable MPI Method for Your Business”, provides readers with information about three different Magnetic Particle Inspection (MPI) methods and compares the level of detail in their test results when performed on the same test piece.
Magnetic Particle Inspection identifies surface flaws in metal products that can be magnetized. This type of nondestructive testing has been performed by Nadcap accredited Laboratory Testing Inc. for thirty years.
The three techniques outlined in Goodwin’s article are:
• Visible dry powder with an alternating current (AC) yoke
• Visible dry powder using full wave direct current (FWDC) in a horizontal bench unit
• Fluorescent wet by full wave direct current (FWD) in a horizontal bench unit.
As noted by Goodwin,“Magnetic Particle Inspection can be performed a number of different ways and oftentimes any of these methods are acceptable under the specification called out for performing the test.” His article explains that these methods not only vary in terms of ease and time to perform, but also in the level of detail provided in the test results. “Since safety and reliability are priorities for anyone in a position responsible for quality, when given an option, it makes sense to choose the MPI method for your finished products that will provide the most dependable results,” suggests Goodwin.
By choosing the three different Magnetic Particle Inspection methods, Goodwin was able to compare the effects on the test results of different electrical currents (AC versus full wave DC) and types of medium or particles (visible dry powder and fluorescent wet suspension) used during testing. The findings led to the conclusion that when the MPI test method is not specified, the fluorescent wet method is more effective and accurate than either visible dry inspection.
Rich Goodwin oversees ultrasonic testing, magnetic particle inspection, liquid penetrant testing, hydrostatic pressure testing and X-ray inspection as the manager of the Nondestructive Testing Department at Laboratory Testing Inc. Quality Magazine is a monthly publication that serves the quality assurance and process improvement needs of manufacturing professionals.
About Laboratory Testing Inc. (LTI)
Laboratory Testing Inc. (labtesting.com) is an independent, accredited testing and metrology laboratory in business since 1984. The company specializes in metals and plastics testing, material analysis, nondestructive testing, failure analysis, calibration services, dimensional inspection, specimen machining and certified reporting of results. The lab is accredited by PRI/Nadcap and A2LA and certified to ISO/IEC 17025, which complies with ISO 9001 and ISO 13485. Testing services include mechanical testing, chemical analysis, metallurgical testing, corrosion analysis and nondestructive testing such as ultrasonic testing, magnetic particle inspection, liquid penetrant inspection, X-ray inspection, visual inspection and hydrostatic pressure testing. Chemistry services are available for metals, powdered metals, ores, ferroalloys, composites, ceramics and plastics. The company’s metrology division performs dimensional inspection and dimensional, pressure, force, torque, electrical, temperature, mass and vacuum calibration services traceable to NIST (National Institute of Standards and Technology). Field calibration, repairs, new instruments and replacement parts are provided.