NDTnet 1998 Aug, Vol.3 No.8

Abstract

Due to the well known human shortcomings the probability to find flaws using Magnetic Particle Inspection (MPI) or Liquid Penetrant Inspection (LPI) can be restricted to only 60 - 75 % and the inspection can hardly be called reproducable. Improvements can be achieved by an automation of the inspection process but this requires a good control of the process. To operate the MPI or LPI equipment at stable and always reproducable inspection conditions modern units are equipped with a monitoring system called "Quality Assurance Package" (QAP). Due to increasing requirements in process documentation (ISO 9000) this equipment can be used additionally for inspection documentation purposes. The QAP can monitor and control the features listed in Table 1. Due to the great variety of possible applications and production conditions using the MPI and LPI techniques one of the major aspects in developping the the QAP system was not to restrict the user to dictated inspection conditions. This required the QAP system to perform relative measurements for example in judgeing whether the magnetic particle suspension can be further used or has to be changed. If the inspection equipment can be run under stable and reproducable conditions due to the QAP the basis for using a camera system for flaw detection is given.The camera system itsself has to be self monitoring too which is given by an artificial crack always being processed together with the inspected parts. Additionally the distance between the camera and inspection-surface has to be controlled. The software for flaw detection was developped in a way that enables the camera of measuring different areas of the parts with different sensitivities in a simgle step and to cover areas that not have to be inspected.

Conclusion:
The development of the QAP system for the MPI and LPI technique together with a camera system for automated flaw detection can give the following advantages:


• controlled, calibrated and documentated reproducable inspection conditions.
• objective and operator-independent equipment control and documentation.
• objective and operator-independent flaw-detection and documentation.
• reduction of costs due to lower labour costs.
• user defined adjustment to a great variety of inspection problems.

Table 1: Parameters monitored and controlled by the QAP system

Magnetic Particle Inspection	Liquid Penetrant Inspection
MP-suspension by automated ASTM-bulb	Penetrant (fluorescence, contamination)
Magnetization current by Hall-Sensor	Process times and temperatures
Magnetization time	Function of spraying nozzles, Level of tanks
UV-Light intensity	Flow rates (e.g. washing, water recycling)
	UV-Light intensity

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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