Product Data Sheet – ETB Series

Demagnetisation Unit with Conveyor

Demagnetisation units of the model series ETB are used primarily in connection with automated systems, where demagnetisation is to be done externally due to a testing issue, i.e. after a visual check. The test objects can be placed manually on the conveyor or with the aid of manipulators. Where the test objects are large and have to be placed on the conveyor with an ejector, the system can be supplied as a reinforced version. Optional lateral guides can allow for exact alignment along the entire length of the conveyor.

ETB demagnetisation unit with conveyor

Product Properties and Part Numbers

Standard model Reinforced model
ETB 250 ETB 350 ETB 450 ETB 550 ETB 250 ETB 350 ETB 450 ETB 550
Field strength (kA/m) 9 8 6.5 5.4 10 10 8 6.2
Mains connection (V) 230 230 230 230 400 400 400 400
Current consumption (I (A)) 5.5 10 14 16.5 4.4 8.5 11 12
Power consumption (kVA) 1.2 2.2 3.1 3.6 1.8 3.4 4.5 4.7
Frequency (Hz) 50 50 50 50 50 50 50 50
Measurement A* 390 480 580 680 390 480 580 680
Measurement B* 250 350 450 550 250 350 450 550
Measurement C* 390 475 577 695 390 475 577 695
Measurement D* 173 339 330 332 173 339 330 332
Measurement E* 160 260 360 460 160 260 360 460
Measurement F* 200 300 400 500 200 300 400 500
Part number 103250 103350 103450 103550 103255 103355 103455 103555

*See diagrams below for measurement references.  All measurements are in millimetres (mm).

Diagram - ETB

Demagnetisation is an important component of electromagnetic crack testing. Residual magnetism in test samples is an issue for many users and the industry demands increasingly better demagnetisation values.

Where workpieces are subjected to a magnetic field due to a magnetisation process – as part of a testing method, processing, or from magnetic lifting equipment – a residual magnetic field will remain in the component after the fieldgenerating source has been disabled (remanence), which must be neutralised. Eliminating this magnetic residue will help avoid negative effects during later processing or when using the workpieces.

The demagnetisation of AC-supplied spools that have a frequency of 50 Hz, occurs by way of the slow retraction of the test object from the field-filled space of the demagnetisation spool, in direction of the spool axis.

At the start of demagnetisation, the field strength must be at least equal to the field strength of the magnetisation. Similarly, the entire area for demagnetisation must be captured. While a field saturation depth of approx. 2mm can be expected in magnetic particle testing with alternating magnetic field, for components that were manipulated with lifting equipment, the entire cross section of the test object must be covered. In the latter case, demagnetisation is achieved with an increased field saturation depth, whereby the field intensity is decreased with low-frequency AC or reversing DC current.

The most important basis for achieving good demagnetisation results is:

  • for parts that were AC-magnetised: demagnetisation at 50 or 60 Hz AC or low-frequency AC.
  • for parts that were DC-magnetised: demagnetisation with low-frequency AC only (e.g. 16 2/3 Hz).

User Recommendations

NDT Method
Magnetic Particle Testing
Accessories Low-frequency generator 16 2/3 Hz:

AC 230V / 50Hz; Out AC 230V (part number 10700)

AC 400V / 50Hz; Out AC 400V (part number 104710)

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