FluxMap® 3D Nondestructive Testing

The FluxMap® measurement equipment was developed for displaying three dimensional magnetic field distributions with high resolution. This new invention makes sible to produce monochrome or colorful “photos” about the magnetic field.

This equipment consists of the high sensitivity magnetic image sensing mouse, portable computer and data acquisition software with 3D displaying capabilities. The most important features of the system are the portability, easy to use, the fast measurement capability, the high spatial resolution and the high magnetic resolution. The FluxMap® was designed with special regard to the on the spot applications. Therefore it is light, durable and battery operated.

One of the important applications of the magnetic field mapping is the nondestructive material testing (NDT). The conductive and/or magnetic materials can be tested this way. During the test, the inspected specimen is placed into alternating magnetic field. If the tested specimen is not homogeneous due to the presence of any flaw inside, it results magnetic perturbation, which can be mapped over the surface as well. In contrary to the traditional electromagnetic NDT techniques, which require sophisticated scanning mechanics for the inspection changes of the magnetic filed distribution over the tested specimen surface, the FluxMap offers easy to use and hand operated solution in order to obtain the digital 3D magnetic “photo” of the inspected area.

SUPER PORTABLE HAND OPERATED DEVICE

The soul of the FluxMap® measurement equipment is a special computer mouse. This mouse contains a Fluxset® magnetic field sensor, which has high sensitivity and high spatial resolution, as well. The sensor can measure one or three components of the magnetic vector field at its location, while the computer mouse senses the position and orientation. The device is equipped with exciting coil system too. These coils can generate adequate magnetic field at the actual position of the mouse, which field can be used for exciting the inspected specimen locally. Therefore, the mouse can be operated in passive, but in active way too.

The active mode of the operation is useful when the tested sample has no own magnetic field (these are the conductive but paramagnetic materials, like some steel alloys, the copper and the aluminum) or the global magnetization of the specimen can not be realized in well defined way. The excitation signal (its amplitude and frequency) is controlled by the computer, which results extraordinary versatile device. By changing the excitation field frequency, the penetration depth and consequently the depth of the investigation can be adjusted in case of eddy current testing. Therefore, the 3D investigation of the conductive materials can be realized this way. The passive operation mode is for the inspection of ferromagnetic objects, when the distribution of the remaining magnetization should be studied or external (i.e. global) magnetic excitation can be applied on the specimen. There is a very special application of the passive mode, when coupled effects can be investigated, like the mapping of the magnetic field variations (like the “Lüders bands”), which are the result of the mechanical strains and/or the magnetostriction.

The computerized data acquisition system combines the data of the actual magnetic field that comes from the magnetic sensor and the data of the sensor location and orientation that is reported by the mouse, and stores them with time values in database. Therefore, the magnetic field values in space, at each position of the mouse, can be identified. The user only has to scrawl all over the surface of the tested specimen, and the FluxMap® can produce immediately the colorful 3D image or “photo” of the magnetic filed distribution can be found inside the investigated area. The most important advantage of the FluxMap® measurement equipment is that it is really fast. First of all, it is not required to scan systematically the whole surface of the tested specimen in the practice, just the critical or suspicious areas are interesting for the user. These problematic areas of the specimen can be recognized easily and quickly, because the applied magnetic sensor can sense the magnetic field perturbation even from a few centimeters distance, due to the fact that the perturbations have spreading. Consequently, the user has not to scan the whole surface with high spatial resolution, but he can concentrate his efforts just on the recognized problematic areas only. On other hand, neither the systematic scanning of the critical surface areas is required. It is, because the FluxMap® can produce usable photos even when some points or scan lines are missing form the database. In case of need, the magnetic field values at the missing locations can be predicted on the base of the Maxwell’s equations and continuality laws.

The FluxMap® measurement equipment offers on the spot applicable quick and efficient way of the inspections. It reduces dramatically the required time for the specimen investigation in case of Non-destructive Testing, while it produce useful and informative 3D magnetic photos of the magnetic filed distribution over the problematic areas.