Process Cycle

1. Billet Entry / Magnetisation

process cycle billet entry

The billet is fed into the system by conveyour (not scope of supply BUCK) and clamped with the two contacting carriages.
Those carriages serve two purposes: to transport the billet through the system and to provide the magnetizing current for the longitudinal crack detection.
Magnetizing current is provided by a motor-generator unit.


2. Reference Marking

process cycle ref mark

After clamping, a reference mark (very small grinding mark) is made to identify the four billet faces (round billets are divided into four sections) for the downstream grinding process. Crack indications will not be visible on the billet surface after the magnetization source has been turned off, but the crack coordinates are electronically stored and retrieved for grinding.

3. Powder Chamber

process cycle powder on

The magnetization current is then turned on and the billet is moved first into the powder chamber where the process powder is sprayed onto the billet surfaces. Cracks on the surfaces lead to a disturbance of the magnetic lines and subsequently to a flux leakage where the special magnetic process powder will accumulate. The result of that process step is a crack indication on the billet surface not visible to the human eye.

4. Blow Off Chamber

process cycle powder off

To refine and enhance the crack indications, excessive powder not sticking to cracks is blown away in the blow-off chamber. But as the billet surface will not be completely smooth, some powder particles will stick to the surface generating the ‘starry sky’ effect necessary for the detection of the proper powder application, an important feature of the process supervision.

5. Optical Fault Registration

process cycle ofrs

Having very clear an detailed crack indications on the billet, it is then run through the OFRS (Optical Fault Registration System) where pictures of the four billet faces are taken in segments. Those pictures are then sent to the computers where the pictures are analyzed, cracks are detected and the crack coordinates calculated and stored.

6. Billet Exit

process cycle billet exit

The billet is then clamped by the billet brake and the two contacting carriages release the billet.