3D Surface Inspection of Hot Steel – Steelinspect® 3D



Steelinspect® 3D inspects hot steel using three dimensional surface reconstruction. Surface defects are detected reliably within the process. At the same time, the area and depth of the defects are measured precisely.


Steelinspect® 3D solves different major problems in surface inspection of hot steel:

  • Steelinspect® 3D can inspect surfaces with temperatures over 1200° C. Steelinspect® 3D is the first system capable of performing surface inspection within the continuous casting process. It allows for monitoring of the hot continuous casting surface, which was previously impossible. The earlier defects in steel production are detected, the lower the resulting costs. Furthermore, Steelinspect® 3D Mobile allows defects to be traced across different process steps, in order to analyse their impacts. The data and knowledge gained this way can be used to permanently improve the efficiency of the continuous casting and rolling process.
  • Unlike conventional 2D surface inspection methods, Steelinspect® 3D also captures and analyses the depths of the defects in the steel. Classification solely on the basis of 2D contrast properties of the defects is typically complex and prone to error. The depth information provided by Steelinspect® 3D is a major improvement on these methods. The pseudo error rate, often quite high for 2D inspection methods, is reduced to a minimum. Raised areas such as scale on top of the surface can be distinguished clearly from inclusions or broken-out pieces of scale.
  • Profile information such as oscillation marks or entrainments can be precisely measured with Steelinspect® 3D.


Steelinspect® 3D uses three dimensional image capture to inspect strip and rolled steel: A laser line is projected onto the hot surface. It's course is tracked and recorded by a high speed camera. The movements of the line on the steel are used to reconstruct a fully three dimensional, digital model of the hot surface. Material speeds typically range from 1m/min to 20m/s and higher. Multiple Steelinspect® 3D inspection heads can easily be placed in series for flat steel products.

The VisionCheck software by Automation W+R automatically evaluates the recorded surface profiles of the material being inspected. Defects such as cracks, oscillation marks, entrainments and inclusions are detected reliably. The captured raw data of the surfaces is stored and can be reviewed or analysed further later, in order to optimise the system by modifying parameters.


Steelinspect® 3D is used for process optimisation at various locations, from the continuous casting line to the rolling mill. The system can be used for the inspection of all surfaces in steel production. Ingot slabs, billets, heavy plates, pipes, wire and profiles can be inspected. In addition to cracks and edge defects, the system also detects and measures defects such as inclusions, oscillation marks and periodical defects in the steel.