LaserSpeed Auto-tracker

LaserSpeed Auto-tracker - Laser Slab Length Measurement

Laser Slab Length Measurement


There is no doubt that the best method of measuring length in a caster or steel mill is by using a LaserSpeed Doppler gauge. For accurate measurement, the object must pass the laser at the reference distance ±100 mm and for some applications, this is not possible. Typically this problem arises on slab casters where there is a large difference between the narrowest and widest slab or wide roller tables where bars are passing and are not in a fixed location but can wander left or right. LIMAB have developed a turn-key solution to solve this measurement application and it is suitable for use on billet/bloom or slab casters or any roller table transporting hot or cold bars. The LaserSpeed is mounted on a servo-driven positioning mechanism that automatically tracks the position of the bar placing the LaserSpeed at the optimum distance. The information about the bar position comes from a separate laser distance sensor. The system is protected by a special forced air cooled housing which keeps the equipment clean and cool.


Quick Spec

Measuring objects Length accuracy Positioning travel Positioning speed
Hot or cold, slabs, blooms, billets or sections < ± 0.03%


800 mm 256 mm/sec

Operating principle

The length is measured using the principle of dual-beam laser Doppler velocimetry which ensures highly accurate measurement without contact. However, for this technique to function, the material must pass at the reference distance ±100 mm. The Doppler gauge is mounted on a servo operated positioning mechanism that automatically tracks the bar position using a separate laser distance sensor. This ensures the Doppler gauge is at the correct distance for optimum measurement.


  • Speed measurement on slab continuous casters
  • Length measurement on slab continuous casters for cut-to-length control
  • Hot rolled section length control at hot saws
  • Run-out length of hot rolled sections
  • Slab length prior to reheat furnace

LaserSpeed® pedigree

LaserSpeed gauges were introduced to the metals industry in 1984 and are proven technology with thousands of installations worldwide.  Measuring length or speed with LaserSpeed ensures the best accuracy and reliable measurement for all types of applications.

Complete solution

The Auto-tracker system allows applications that would have once been difficult or impossible to accomplish reliably to be done with ease. LIMAB provide a complete turn-key solution including all hardware and software.

Replace water-cooled contact rollers on casters

With accuracy better than ± 0.03%, irrespective of the material grade, temperature, surface condition the Auto-tracker is ideal for replacing traditional water-cooled contact rollers found on continuous casters.  The measurement is more accurate, reliable and due to non-contact technology much less costly to maintain.

Eliminate the need for multiple hot metal detectors or photocells

Traditionally sections lengths are measured with banks of HMD’s or photocells together with a tachometer driven by a contact roller. In the harsh steel mill environment, the position and alignment of the photocells are difficult to maintain resulting in poor reliability and accuracy. The Auto-tracker eliminates all these problems.

Speed range 0… ±19,000 m/min for 1.5 m stand off
Accuracy Better than ±0.03%
Repeatability ±0.02%
Measuring object All metals up to 1100 +C°
Stand off distance 1.0, 1.5, 2.0, 2.5 or 3.0 m
Laser class 3B
Outputs Profibus, RS232, RS422, Ethernet, Quadrature Pulse
Servo travel 800 mm
Servo speed 256 mm/sec
Distance laser type LIMAB XLR30
PLC type Siemens
Cooling Air blower & filter assembly
Cooling air volume 2000 m³ / Hour
Dimensions of housing (typical) 1400 x 600 x 300 mm
Adjustable mounting stand Provided to suit the application

What Our Customers Say…

Accurate length control at the hot saws is critical to our operations, we needed to work with a company that understood our requirements and had know how to deliver an effective solution. LIMAB Ltd exceeded our expectation in delivering a turn-key measuring system that will improve our efficiency.

Marco Damme – Rolling Mill Maintenance Manager