MAGNETIC PARTICLE PATTERN IN RADIATING FORM NEAR CORNERS OF A KEYSLOT ON WORKPIECE SURFACE

摘要

The objective of this study was an explanation of the reason causing the magnetic particle pattern in radiating form near corners of a keyslot on workpiece surface in theory. An item analysis was conducted on the distribution of magnetic charges along the convex edges of a discontinuity on the ferromagnetic workpiece surface at magnetization and the magnetic force acting upon a magnetic particle near the corners. The principle finding of the item analysis was that around a large square hole, a parallelogram slot and near corners of a keyslot on the workpiece surface there sometimes will appear magnetic particle pattern in radiating long straight lines starting from the corners of them and spreading out along the 45° lines. On the basis of these findings the deduction mentioned above was verified not only by a magnetic particle testing experiment made in the summer of 1995 by the author etc, but also by some experiences of magnetic particle inspection in production.