Frequently Asked Questions

FAQs Overview

• Is contact or laser thickness measurement of metal strip better?

  When using the latest types of contact gauges (e.g. MTP-1302AF or MIA-1001A), contact measurement is the most accurate in the world with regard to real conditions of use in cold rolling mills of metal strips, where it measures without reducing the guaranteed accuracy of 0.5 or 1 μm in very difficult working conditions. Contact gauges do not mind an oily or dirty strip of any roughness, there is no problem changing the height of the strip during measurement in centimetres, changing the tilt or waving of the strip thanks to the floating head that copies the unevenness of the strip. Contact gauges measure materials of any composition very accurately, so they are also used for accurate on-line calibration of X-ray gauges. The materials used for contact sensors and their cooling allow measurements with a temperature dependence of less than 1μm/200°C. The shape of the measuring tips guarantees that even the sensitive surface of the strip will not be damaged, and the service life of the sintered diamond powder measuring contact is decades. With contact gauges, it is easy to check the accuracy continuously - with a value of 0.0 µm on the display after measurement. Thanks to simple calibration using commercially available standard gauges, direct metrological traceability is guaranteed. The advantage of contact gauges is their lower prices and low cost of spare parts, mostly less than 1 % of the meter price per year. Their disadvantage is the limitation of the strip speed below 900 m/min and the maximum depth of measurement from the edge of the strip to 310 mm, which is usually sufficient for connection to the control loop even for wide strips.

  Laser gauges have guaranteed measurement accuracy limited by many conditions, which need to be found in the parameters below the line, where at least some reputable manufacturers state them. For accurate measurement of laser gauges, a clean surface is required, no oil droplets, no emulsion, no fumes, a clean environment without dust, a belt tilt below 1°, a change in the strip height of only a few mm without vibrations. With triangulation measurement methods, the problem is to check the alignment of both sensors to one axis, changing color, roughness and glossy surface of the measured strip. Therefore, the most modern laser gauges (e.g. LMT-750A) do not use triangulation laser sensors, but four-point laser sensors of a new generation, which do not contain electronics, only lenses and connection to the evaluation unit via optical fiber. The electronics of these four-point laser sensors can automatically check the correct alignment of the sensors against each other in one axis, because misaligned measurement will worsen the accuracy of the measurement of the corrugated strips several times over, and the automatic calibration will only hide this measurement error. The disadvantage is the higher purchase price or short service life of cheap laser sensor models. In the event of an accident, for example when the strip breaks, the price of repair is usually many times higher than that of contact thickness gauges, which can usually withstand the strip break without damage. The advantage of laser gauges is the possibility of measuring strips with a temperature above 250°C, their depth of measurement, which can be scanned over the entire width of the measured strip, and the almost unlimited speed of the measured strip.

• What is the space requirement for MTP instruments?

  MTP gauge including travel arrangement width is 180 mm (width of MIA gauge is 73 mm, LMT head has width 80 mm). A base plate is 245 mm under the strip (on request up to 105 mm only). Beyond or ahead of the strip a space must be provided for operating movement of the instrument in accordance to submitted design. Drawing showing the outside dimensions, instrument's travel arrangement and evaluating unit will be prepared and submitted after an agreement on the type of measuring unit required is reached.

• What is included in the MTP instrument delivery?

  Delivery includes the sensor head with positioning system, PLC box, touch panel 7" display and pneumatic distributor with air beneficiation, cables & pipes for interconnections. The client provides the base plate under the positioning system in accordance with the supplied documentation.

• Can automatic zeroing be done at thickness gauge positioned next to the strip?

  Yes, but this "zeroing" is never done automatically due to possible error in subsequent measuring. Deviation of > 0.002 mm from 0.000 value on the display after gauge head is out of the strip would possibly necessitate double check the gauge by operator or service crew. Auto-zeroing have only gauges that are not accurate and stable, to hide measurement errors.

• Is it possible to measure sheet thickness?

  The MTP gauges are used for a continuous measurement of strip thickness, sheets you can mesure by laser strip thickness gauge LMT.

• Is it possible to use parts from old original instruments from other manufacturers?

  No, due to different designs it is not possible to use any part of the old or obsolete devices from other manufacturers.

• How the instruments are priced and what are the purchase requirements?

  As a minimum it is necessary to state the manual and/or automatic option, the required distance of measurement from the strip edge (130; 210; 310 mm), any other special requirements for serial data output and equipment of outputs and accessories (pen recorder, collection of data with report printing tc). Further more, minimum and maximum of strip width and thickness, type of material, speed of the strip and positioning requirement.

• How often is the instrument calibrated, and who does it?

  Once a year, provided by UVB TECHNIK appointed personnel or trained local agent technicians or customer´s metrology representative.

• What is necessary to change regularly on the instruments?

  Air filters must be cleaned or changed regularly.

• Are any special measuring or tools requirements are necessary for common reparations and adjustments?

  For normal - common - adjustments and reparations except digital voltmeter and etalons of thickness for calibration purposes (etalons are part of delivery) no other special instruments are needed.

• Who provides the service?

  Training of operators and maintenance is a part of installation procedure; mostly operating personnel does the local maintenance, which is not complicated. E-mail or faxed requirements are detailed explained and if necessary our or local agent technicians are available.

• Where is the most convenient place for placing of the instrument?

  The most convenient place is where is the maximum strip tension, with minimum vibrations and strip flutter lesser than ? 20 mm.

• Who installs the instruments?

  Installation, operator's and maintenance training is always done by UVB TECHNIK.

• Can the gauge be connected to PC or a ?superior? system?

  Yes, by serial link PROFINET, PROFIBUS, EtherNet/IP or on request

• Can gauge be connected to regulation loop? What are the outputs?

  Yes, it can. Standard outputs are: thickness deviation 0-20 mA (? 10 V by requirement), nominal thickness output 0-10 V. Gauge MTP is also equipped with serial port RS485.

• Speed of sample taking / measuring?

  MPT gauge measures continually and is possible to order analogue output with 5 ms delay. Digital display shows 200 readings per second (1000 redings per secon on request).

• What is the thickness measuring accuracy?

  Range 0- 2 mm ≤ 0.5 µm, and full range 0 - 9 mm ≤ 2 µm

• What are the minimum and maximum strip widths?

  Maximum width is not limited, although measuring can be done only to a distance of 310mm from the edge. For width of lesser than 40 mm a MTUP (Continuous Narrow Strip Thickness Gauge) gauge should be considered.

• What is the gauging distance from strip?s edge?

  According to gauge type - maximum 130, 210 or 310 mm (MTP-1301, MTP-2001, MTP-3001).

• What is the maximum strip speed?

  Strip speed is not the eliminating factor for the measurement accuracy, but for a lifetime of guiding rolls and operational safety of the instrument. It is recommended that the operational strip speed should be lesser than 900 m/min.

• Is MTP gauge difficult to operate?

  No. Operator only engages or disengages the unit and checks value 0.000 mm on the display after the unit's disengagement. In case of automatic regime everything is done automatically.

• Is it possible to change the height of strip in the line?

  Yes. Measuring head has a vertical guide equilibrating the strip heights in the range of -10 to +30 mm (higher range on request).

• Rolling Oil, Emulsion, dirty strip ? are they detrimental to the measuring head?

  No, inside of measuring sensors is pressure air barring penetration of any impurities inside the sensors. While measuring, due to the pneumatic contacts pressure is foiled surface substance penetrated and will not influence measuring accuracy.

• Is it possible to install more heads to measure in multiple lines simultaneously?

  Due to "gauging head" design not.

• Is it necessary to measure the thickness at the strip centre?

  If we know at least approximately transverse profile of rolled strip (this stays generally the same over the whole strip width) it is not necessary to measure thickness in the middle of the strip. Even on "Wide Strip Rolling Mills" (>1000mm) some producers gauge only 130 mm from the strip edge.

• Is it possible to measure strip thickness at the central line?

  It is possible only at the strip width of up to 620 mm.

• Can the unit be continually moved transversally and gauge the profile?

  Continual movement (without interruption of measuring) while the strip is moving is not possible. Only by steps - sensors and guide rolls must always open while the instrument moves. Exception is "Special Application" instruments for strip width of 180 mm and strip speed of lesser than 6 m/min.

• Is it possible to measure the strip?s transverse profile?

  It is possible to estimate the profile by measuring the thickness at the strip edge and at maximum distance from the strip edge (310 mm). Unit with automatic movement can be moved to position to the edge of the strip by pressing the button and subsequent button pressing at the adjusted transverse stop (to middle of the strip max. approx. 620 mm) or manually to any other position defined by maximum width of measurement (according to type up to 310 mm).

• Can the MTP unit be moved in and out while the strip moves?

  Yes, while the unit is in motion the guiding rolls and sensors are in the "open position" to prevent rolled strip damage.

• What is the difference between manual and automatic side positioning?

  Manual units are positioned by hand gripping the handle from the front or back of the moving strip, the automatic one uses automatic shifting with help of pneumatic cylinder and strip edge detector. In case of automatic shifting the operator pushes the button and MTP is moving toward to the strip - optical sensor checks the strip edge and stop the measuring head in adjusted distance from the edge for variety strip widths.

• Isn?t MTP instrument damaged by strip breakage?

  MTP instruments with automatic guiding have several safety elements minimizing their damage by strip breakage. The sensor head is equipped with inductive sensor checking strip's lift or waviness - if sensor is closed the instrument automatically slips out from the strip. Head is furthermore equipped with an optical sensor checking the presence of rolled strip between sensors and will automatically position the instrument on the side of the strip if strip break is sensed. Head is also equipped with the Micro-contacts checking strip moving to the side - MTP gauge automatically goes out of the strip. If the rolling mill is fully automated, it is possible to use automatic evaluation of coming danger (strip tension lost, values out of limits, sudden change in rolling parameters etc) - could be used for shifting of the MTP measuring unit out of danger / damage zone. Movement is usually done by pneumatic cylinder and shock absorbers softening the end movement at high speed. In case of instrument not reacting in time, unit is finally protected by additional mechanical safety design - security breaking cube, which breaks down due to the accident and frees the measuring head which will hangs on the "kabelshlep" (chain). MTP gauge shouldn't get damaged exception being this cube and it would be necessary to change only this security breaking cube.

• What is the lifetime of the measuring contacts?

  Contacts are not from natural, brittle diamantes but from sintered diamante powder with nearly unlimited lifetime. Our oldest gauges are working for more than 25 years without any changes whatsoever.

• Is it possible to measure plastic and other synthetic materials?

  Yes, MTP gauges can measure paper, synthetic materials, rubber, lacquered strips etc. Only condition is that surface of strip is not "semi-liquid". If necessary, please forward your sample for a trial.

• Is it possible to measure a ?strip coating??

  MTP instruments measure only total strip thickness including coating, not the coating only.

• Is it possible to measure aluminium with contact instruments?

  Yes. Although manufacturers of Al strips mistrust usage of contact instruments, the applications had always been highly successful both in continual contact measurements and in the on-line calibrations of contact-less instruments on wide-strip rolling mills - where initially both instruments measure simultaneously and after automatic calibration of X-ray instrument, the contact MTP measuring head is moved out. MTP gauges for aluminium application have not steel guiding rolls coated with chrome-diamond surface, but rather a polyurethane coating which leaves no marks on the strip surface.

• Does the measuring contact leave a mark on the measured strip?

  No - the force on the contacts is regulated by air pressure from about 0,2 N. The actual measuring contact point is neither sharp nor rounded but is actually a flat surface of 0,8 - 1,4 mm diameter with bevelled edge in accordance to application. Thanks to this flat surface there are not problems with trace on the strip surface.

• Is a stepping motor included in the sensing head?

  "Measuring lift" of both sensors is 10 mm and whole range of thickness gauging 0-9 mm is covered without the necessity of sensors mechanical transfer in the head. (both sensors are clamped in a yoke). MTP instruments therefore don't have stepping motors or an adjusting micrometer.

• Is it possible to gauge with one head strips ranging from 0,005 mm to 9 mm?

  All types of MTP instruments have one only range 0 - 9 mm. During actual measuring the strip thickness can move in the full range.

• Is it necessary to set a ?nominal strip thickness? before measuring?

  No, digital display shows absolute value of strip thickness. Only in case where measurement of deviation is requested from required thickness on analogue display it is possible to set up nominal thickness digitally. Lift of both sensors is 10 mm and a complete range 0-9 mm is covered without necessity of mechanical movement of the sensors inside the measuring head (both sensors are clamped in a yoke). Mechanical movement of sensor by means of micrometer bolt installed in instruments of similar designs might be source of additional faulty indications due to wear out of the micrometer's bolt.

• What is Absolute Measuring of Thickness??

  MTP instruments display digital absolute thickness in micrometers; at "off line position" value 0.0000 mm should be shown, enabling easy control of measuring correctness. Thanks to this, MTP instruments can be used for "on line calibration" of contact-less gauges.

• Could UVB measuring sensors be installed into competition units?

  Due to different design unfortunately not.

• Is the head heated in order to lower the errors caused by temperature variations?

  Heating of the measuring head is not necessary, head and sensors are "heat compensated" by material and sensors are cooled down by air. Thanks to cooling the sensors and contacts through the sensor body, strip thickness can be measured at temperatures of 250°C with a temperature dependence of ≤ 1 µm/200°C without need of heating the measuring head.

• Are the sensing heads inductive as those of your competitors?

  No, sensors are coil-less, electronic-less and have no brittle materials. Except few plastic components they consist only of stainless steel materials. Nothing is adjusted in the sensors. They are nearly indestructible except for severe mechanical abuse. Heads are from time to time tissue-cleaned and degreased. Accuracy (linear) is better than 0,01% (at 10 mm rise <1 µm).

• Can ultrasound be used?

  Ultrasound sensing probe must be by suitable intermediate media always in contact with the measured strip, which is difficult to achieve with a moving strip. We don't know of any permanent usage at rolling mill plants.

• Is unit-using contact gauging better than contact-less unit?

  Contact measuring will achieve more precise results cutting off oil or emulsion strip contamination, material composition and hygienic and safety requirements. Contact-less units are preferred for hi-speed (tandem) rolling and at hot rolling. Naturally, at much higher price. Generally, contact gauges are more suitable for narrow strip rolling (< 1 metre width) speed < 900 m/min, for nonferrous metals, alloys and bi-metal strips.

• What is the principle of gauging the thickness of rolled strip by MTP gauge?

  Floating head of the unit holds the moving strip with the help of two guide rolls - following its small deviations. In the head, between the two rolls are two sensors with diamond contacts. Sensor's movement differential values are transferred to signal conditioner placed in evaluation unit, changed to analogue signal and depicted as an absolute thickness in micrometers or as a deviation from required (nominal) thickness.

• What is the difference between types MTP-1301, MTP-2001, MTP-3001?

  The difference is only in the maximum possible depth of measurement from the rolled strip edge. MTP-1301 = 130 mm, MTP-2001 = 210 mm, MTP-3001 = 310 mm.