For further information on our newest thickness measurement system please check our flyer alpha.ti 2.0.

Contactless online thickness measurement - alpha.ti

The manufacturing of strip-like products requires the measuring of the thickness to keep specified tolerances while guiding the manufacturing process securely. nokra offers measuring systems to be integrated in a production line for a contactless online thickness measurement. These systems measure the thickness continuously without any delay providing the decisive information to improve the manufacturing process and to achieve an efficient quality assurance.

The laser measurement is based on the principle of laser triangulation. The laser measuring systems of nokra are specified and inspected on the basis of established national and international standards as well as on the guideline „Measurement System Analysis“ of the international car manufacturer and supplier industry.

The key component of a thickness measuring system are laser triangulation sensors for the measurement of distances. The thickness is determined using the synchronously measured distance values from the top and bottom side of the strip-like product.

Principle of thickness measurement with laser triangulation sensors (s = sheet metal; R = rolling stand; LS1 LS2 = laser triangulation sensors)
Real time visualisation

Material independent measurement

Laser thickness measurement is capable to measure various kinds of materials, such as metal, foam, plastics, mineral rock wool, nonwoven fabrics, elastomers, wood, paper. Thereby, the properties of these materials vary in a wide range: from metallic glossy surfaces to surfaces with scale layers, from white to black, from smooth to rough, from cold to red-hot, from opaque to translucent. The laser measures the thickness of the material independent from the specific material density. This is valid for red-hot steel as well as for porous foam. A knowledge about the composition of the material is not necessary.

An aerodynamically optimized air wipe unit keeps the sensor’s optical window free of dust and rolling oil
Automatic adjustment of thickness gauge during production
Typical laser thickness gauge for metal sheets

Highest precision

The laser sensors of nokra applied for thickness measurements offer a significantly improved precision in comparison to conventional sensors. nokra laser sensors are based on a new method gaining an enlarged information from the measuring radiation.

Technological advantages

Feature Laser measurement Tactile probe Radiometric measurement
Contact free + - +
Fast reaction on thickness changes + - -
Small measuring spot + + -
Low maintenance effort + - -
Harsh operating conditions + + +
High availability + - +
Eco-friendly technology + + -
Measuring object Laser measurement Tactile probe Radiometric measurement
Sensitive surfaces + - +
Independent to density variations + + -
Independent to changes of the material composition + + -
High temperatures + - +
Porous surfaces + - -

Technical data

Feature alpha.ti/6 alpha.ti/12
Measuring principle laser triangulation laser triangulation
Measuring range of upper sensor/distance to passline 25 mm/115 mm 80 mm/265 mm
Measuring range of lower sensor/distance to passline 8 mm/35 mm 8mm/35 mm
Thickness of measured material max. 6 mm max. 12 mm
Diameter of measuring spot 0,05 mm 0,1 mm
Velocity of material to be inspected 5-2000 m/min 5-2000 m/min
Surface/Material properties no restrictions, examples: metallic glossy, scale layers, dark, porous, coloured no restrictions, examples: metallic glossy, scale layers, dark, porous, coloured
Sample frequency up to 50 Hz up to 50 Hz
Integration time 1-1000 ms 1-1000 ms
Accuracy of thickness measurement +/- 0,001 mm +/- 0,003 mm
Adjustment automatic adjustment procedure automatic adjustment procedure
Window protection system An aerodynamically optimized air wipe unit keeps the sensor's optical window free of dust and rolling oil An aerodynamically optimized air wipe unit keeps the sensor's optical window free of dust and rolling oil
Laser    
Laser class 1 to 3 R 1 to 3 R
wavelength visible visible
Ambient temperature for measuring operation -5 to +60° C (if ambient temperature is > +45° C, external cooling is needed) -5 to +60° C (if ambient temperature is > +45° C, external cooling is needed)
Humidity not condensing not condensing
Output signals analog, profibus, profinet, TCP protocol, output frequenzy adjustable analog, profibus, profinet, TCP protocol, output frequenzy adjustable
Input signals incremental encoder, trigger signals, profibus, profinet, ethernet (TCP/IP protocol) incremental encoder, trigger signals, profibus, profinet, ethernet (TCP/IP protocol)
Protection class of C-frame IP 65 IP 65
Life time of laser modules MTBF=80.000 hours MTBF=80.000 hours
  B=400-1250 mm B=400-1250 mm
  C=150 mm C=350 mm
  D=mind. 190 mm D=mind. 190 mm