In short: a measuring wheel slips on hot, scaled steel, and every slip means a crop cut in the wrong place or a coil that is longer than the order. A laser velocimeter measures speed and length without touching the strip, to 0.05 %. BTGC supplies KELK sensors for Saudi steel and aluminum mills.
In a hot strip mill, precision is profit. The crop shear cuts the head and tail of each transfer bar; cut too much and good steel goes to scrap, cut too little and a defective end reaches the coiler. The coil is sold by weight and ordered by length; every metre over the order is given away. Both decisions depend on one measurement: how fast the strip is moving and how far it has travelled.
Why contact measurement fails
A measuring wheel pressed against the strip slips on scale, water and vibration. The error is small per metre and large per shift. Wheels wear, bearings fail in the heat, and the sensor sits in the harshest spot in the mill.
How a laser velocimeter works
A laser Doppler velocimeter projects two laser beams onto the strip surface. The moving surface scatters the light; the frequency shift between the beams gives the speed directly, with no contact and no slip. Integrating speed over time gives length. The sensor sits away from the strip, behind an air purge, and survives heat, steam and dust.
| Measurement | Contact wheel | KELK laser velocimeter |
|---|---|---|
| Speed and length accuracy | Degrades with slip and wear | Better than 0.05 % |
| Maintenance | Wheels and bearings | Optics cleaning only |
| Position | Touching the strip | Stand-off, air-purged |
| Effect on yield | Crop loss and length giveaway | Exact crop cuts, coils to length |
KELK from BTGC
KELK, a Vishay Precision Group brand founded in Toronto in 1953, is the measurement standard of the world's rolling mills. The range BTGC supplies in the Kingdom covers:
ACCUSPEED non-contact laser velocimeters for speed and length
ACCUBAND stereoscopic width gauges that measure strip width even when the strip vibrates or tilts
Rollmax roll force load cells, hermetically sealed and forged from a single block of steel
Applications in the BTGC catalogue are hot strip mills and plate mills at Hadeed and SULB, and aluminum rolling. See our page for KELK in Saudi Arabia and the full machinery and measurement offer.
Thickness and flatness too
For thickness and profile, BTGC supplies IMS Messsysteme X-ray and isotope gauges, so a mill can source its force, speed, width and thickness measurement through one partner. Together they feed the automatic gauge control that holds strip tolerance.
BTGC support in Dammam, Jubail and Yanbu
BTGC supports the metals and steel plants of Jubail and the Eastern Province from branches in Jubail and Dammam. For a quotation send the mill type, strip speed range, stand-off distance available and the mill automation system the sensor must feed.
Questions buyers ask
Can a laser velocimeter replace an existing wheel one for one? Usually yes; it needs a mounting position with a clear view of the strip and an air purge.
Does scale on the strip affect it? No, the Doppler measurement reads the surface whatever its condition.
What about calibration? The measurement is absolute; verification is by a length check against a known cut.
Contact BTGC
Email info@btc-ksa.com or call +966 13 856 0528. Branches: Dammam, Jubail and Yanbu. Request a quote.