In-Line MPT System for Steel Billet (LM)

In-Line MPT System for Steel Billet (LM)

Line-Magna (LM)

This system performs in-line surface flaw inspection of steel billet utilizing fluorescent magnetic particle testing method while the billet being transferred on the V-roller conveyor. All surfaces and corners of the billet is visually inspected and marked by inspectors for removal in the grinding process later.


  • In-line continuous inspection during the billet being transferred
  • Low equipment cost, less installation space
  • Flaw inspection can be done by two inspectors. This is less than one half compared to required number of inspector of Axial electric current magnetization method.
  • Detecting longitudinal, transverse and corner defects simultaneously
Main Specification
Type of steel to be inspectedCarbon steel, Low alloy steel and Special steel
DimensionSquare billet 120-160 mm sq.
Billet transfer speedMax. 15 m/min. (V-roller transfer)
Magnetizing methodCombined magnetization with Yoke coils and Ring coil
MPT materialFluorescent magnetic particle suspension
Defects to be detectedSurface breaking natural flaws (crack, scab etc.)
Detecting accuracyLongitudinal flaw (crack): more than 0.3 D x 10 L mm
Transverse flaw (scab) : more than 0.3 D x 10 dia. mm
Electric powerAC 400/440 V±10%, 3-phase, approx. 150 KVA
AirMore than 0.4 MPa, 5.0 Nm3/min.
Normal consumption : approx. 0.8 m3/min.
WaterService water 100 L/min.
Main Equipment
Suspension spraying equipmentSuspension spray nozzles
Magnetizing equipment(4 sets of Yoke coils and one Ring coil) x 2 sets
Suspension tank500 L tank with circulation pump
UV lightSuper-Light E-40-2 x 8 sets, Mirror units
Control equipmentControl panel, Magnetizing power source panels, Local operation panel

Inspection Procedure