Evaluation of the Performance of Magnetic Indicators for Magnetic Powder Control of Railway Rolling Stock Parts

Abstract

Purpose: To evaluate the performance of various luminescent magnetic suspensions on the example of individual small-sized parts of railway transport, differing in geometric shape, color, surface roughness and the presence of paint coating. To show the need to test magnetic suspensions, including ready-made ones, in aerosol cans on tuning (control) samples, taking into account the color, the presence of a non-magnetic coating, and other characteristics. Methods: Comparison of the obtained magnetic powder indications during wet magnetic powder control under conditions of magnetization of rolling stock parts by the applied field method using the MD-12PSH flaw detector. In practice, identical conditions have been maintained for magnetizing components at the center of the solenoid, uniformly applying magnetic suspension through aerosol can and sprayer to the surface, as well as inspecting for the presence of accumulations of magnetic powder particles under both daylight and ultraviolet irradiation. Results: The experiment has shown that the technical characteristics of the magnetic indicator stated in the passport by the manufacturer shouldn’t be fully trusted and relied on. At the same time, the use of one or more standard or tuning (control) samples with a huge range of control objects is not enough. Practice shows that, taking into account the fact that surfaces of parts differ, it is necessary to conduct a comparative analysis of magnetic suspensions for the brightness of powder glow, contrast, measured length of the magnetic indication on parts with artificial or natural defects with exactly the same surface. Practical significance: The article shows that it is necessary to use for each control object its own tuning or control sample. Only those objects of control that are identical or comparable in size, shape, color, roughness, and other characteristics fall under the exception. Therefore, only one sample can be used for them.