Automatic magnetic particle testing system DIO5000 – application

- An Automatic System for Defect Detection on Train Wheels during Magnetic Inspection
- Non-contact method

High safety standards required in the management of railroad lines demand the inspection of train wheels directly after production in order to detect the presence of surface cracks that could seriously affect the integrity of the train, and therefore passenger’s safety.

System overview
During the last year, STARMANS company have been developing an automatic system for surface defect detection on train wheels. The main goal was to develop the highly reliable system based on image processing algorithms that gives an warning of surface flaws to prevent possible future accidents.
The system is based on magnetic inspection where the train wheel is put into the magnetic field and the cracks cause a magnetic stray field. By this technique the cracks are visible and they can be easily recorded using high speed digital camera, also developed in STARMANS company. In the developing stage, we simulated the magnetic field to find out the optimal position of train wheel in magnetic field for the best defect visibility.

During the magnetic inspection of train wheel, the surface is scanned by digital camera. The recorded pictures are promptly evaluated of our proposed image processing algorithm. Whole surface and different sizes of train wheels can be inspected.
The proposed algorithms can be briefly described in two main steps:

Noise reduction
The picture is corrupted with relative high noise level and detection process is more difficult - hardware part.

Defect detection
Defects have to be recognized from scratchy surface of train wheel. Only the flaws have to be detected - software part.

Both noise reduction and detection algorithms are based on simple mathematical equations and implemented in our developed digital camera. It means that the pictures are processed on-line, during inspection.



Summary
The presented automatic system DIO5000 for defect detection on train wheels was completely developed in STARMANS electronics company. With this system it is possible to detect the surface flaws on train wheels. The digital camera with adequate resolution was developed for the surface scanning and proposed digital image processing algorithms are implemented both in hardware and software parts. In case of flaw detection, it is possible to detect the flaws in length of 1 mm and thickness of 0.3 mm. The proposed system is fully automatic and it is able to successfully detect and classified flaws. The system can be modified for special desired industrial application