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A tension reading can change after a guide roll is moved even though the material is pulled with the same force. Tension sensor selection must therefore include the material path and the measuring direction, not just the maximum tension on the machine specification. For web, wire and cable equipment, establish how the process tension becomes a load on the sensor before choosing a capacity.
Tension sensor selection depends on the material path
Draw the entry and exit directions at the sensing guide, with force arrows acting on the guide. Include all operating positions, especially a moving dancer or a path affected by roll diameter. The vector sum of the material forces determines the guide load; only the component acting in the specified measuring direction contributes as intended.
A small deflection of a nearly straight material path can produce a small radial force even when line tension is substantial. Increasing sensor capacity will not improve that weak signal. Conversely, a larger change in direction can increase guide load and consume measuring range. Confirm the geometry before calculating the required capacity and gain.
Use the actual tensions on each side where friction or drive action makes them unequal. For a supported roller, also include its weight, the bearing reactions and their projection onto the measuring direction. A catalogue capacity is a sensor-load rating, not an automatic permissible line-tension setting.
Match the sensing structure to the machine
| Candidate | Documented arrangement | Question to settle before ordering |
|---|---|---|
| MV-LC0130 | Radial tension sensor with one end fixed and the other loaded; reference range 10-50 kg | Does the guide apply the calculated radial load at the intended location and direction? |
| MV-LC0147 | Through-shaft tension load cell with a bearing-based roller installation | Which shaft, bearing and capacity configuration matches the proposed roller and its supports? |
The MV-LC0130 is documented for yarn, metal wire and fabric-tension applications. Its reference sensitivity is 1.5 +/-0.05 mV/V, with 5-12 V excitation. The listed 10-50 kg range uses the catalogue's load notation; state the process tension in agreed force units and provide the geometry needed to relate it to that rating.
The MV-LC0147 uses a different installation. Obtain the complete structural specification rather than ordering from a family-wide capacity range. Shaft diameter, bearing arrangement, mounting dimensions and capacity must belong to the same offered version. Neither design is automatically a substitute for a clamp-on instrument used to check a stationary steel rope.
One measured support or two?
For a roller supported at both ends, the reaction at one end depends on where the material loads the roller. A narrow web moving sideways can redistribute the reactions without an equal change in total tension. Decide whether both supports must be measured, and define how their outputs are combined.
Do not simply double one reading unless the distribution remains valid across the permitted web positions and operating states. Check the roller and frame stiffness, bearing alignment and thermal movement. If mechanical contact changes after warm-up, an electronic zero adjustment may hide the symptom without correcting it.
For a cantilever guide, check the permitted loading point and the resulting moment. A replacement guide with a longer overhang can change the loading condition even if the material path looks similar. Include the guide dimensions in the enquiry, not just the sensor's threaded mounting size.
Commission the measurement before tuning tension control
Start with a defined unloaded condition and record the individual sensor readings. Apply an appropriate known force through the intended material path using an approved test fixture. Repeat at the relevant guide positions and compare increasing and decreasing loads. The test should establish the conversion from sensor signal to line tension before the controller is tuned.
Then test under the intended machine motion, including the conditions relevant to acceleration and stopping. Keep the measured value and controller command available in the record. Oscillation may involve the drive, roller inertia, friction or signal delay; raising the filter setting is not a diagnosis.
Specify the excitation, amplifier range, update timing and output interface as a complete chain. The cited MV-LC0130 data describe an mV/V sensor, not a native 4-20 mA or Modbus RTU device. The PLC signal guide explains where the required conversion belongs. Ask for timing information for the selected electronics rather than inferring control bandwidth from the sensor's static accuracy.
Questions from line upgrades
Q1. Can the operator zero the tension reading with material threaded?
Only under a defined reference condition whose residual force is known and allowed by the procedure. Zeroing a tensioned web can remove real process load from the indication. Record whether the reference includes roller weight, bearing preload and material contact before enabling automatic adjustment.
Q2. Why did the indication change after replacing a bearing?
Check fit, preload, friction and support position before changing calibration. The replacement may have changed the force transferred to the sensor. Compare no-load and known-force readings with the earlier baseline and re-verify the installed conversion when the mechanics have been restored.
Q3. What makes an enquiry specific enough to select a model?
Provide the material, width or diameter, tension range, speed, guide drawing, entry and exit angles, roller weight and support arrangement. Add the control purpose and receiving electronics through METRAVON enquiries. Identify whether you need sensors alone or also mounting, conditioning and commissioning support so the quotation has a clear scope.
Summary
Calculate the force at the measuring support before selecting the tension sensor. Keep guide geometry, bearing conditions and the electrical conversion under control, then test the installed relationship to line tension. A change to the material path or roller assembly can require re-verification even when the sensor itself is unchanged.
