Situation

Due to its high potential for automation and the extensive range of applications, non-destructive testing (NDT) eddy current methods is an inherent part of NDT applications. These methods can be applied to any electrically conductive material. Electrical conductivity and magnetic permeability are the relevant physical material properties which influence the test and, therefore, include the information content. These parameters depend on the material‘s quality characteristics such as

•     heat treatment and texture formation,
•     texture differences such as case and nitriding hardness
layers, liquations etc.,
•     mechanic properties such as firmness, hardness,
residual stress etc.,
•     mixing ratio of alloys.

Besides material properties, eddy current inspection is used to detect changes of specimen shapes and material defects. For example

•     surface and near-surface defects,
•     lift-offs and layer separations,
•     corrosion layers, subsurface corrosion,
•     diameter deviation of wires, rods, pipes, balls etc.,
•     thickness of metallic and non-metal layers,
layer thickness of multiple conductive layers and
thickness of interlayers, pipes, sheets etc.

Solution

The inspECT board developed by Fraunhofer IZFP comprises the necessary components of an all-purpose eddy current testing system. The inspECT board is able to operate in single- or multi-frequency multiplex mode, in sensor multiplex mode or in a mode that combines the two procedures. The main features are:

•     Single- or multi-frequency operation with up to
16 testing frequencies from 100 Hz up to 10 MHz.

•     Multiplex sensor operation with up to 16 sensors realized by
an external multiplexer which allows flexible positioning
of the sensor-near electronics. This method enables
the realisation of long testing distances.

•     Setup of multichannel systems by cascading multiple
inspECT testing boards is guaranteed by the modular
customer-adapted concept.

•     High sample rate: 25,000 samples/s in single-
frequency mode,
up to 700 samples/s in operation mode at 16 frequencies
and / or 16 multiplexed sensors.

•     Integrated triaxial coordinate interface
(optional with differential receiver).

•     Real-time accessible inputs and outputs for process control.

•     High-performance hardware enables signal processing
in real-time already on the inspECT board.

•     100 Mbits full duplex Ethernet interface for testing data
and parameters.

•     High-performance software with integrated regression
analysis.