Roller construction
Record whether the measuring roller uses a live shaft, dead shaft, pillow-block support, flange mounting or cantilever arrangement. This determines which mechanical load-cell families can physically fit.[2]
Resources / Web Tension Load Cell Selection
How to Select a Web Tension Load Cell
A load cell should be selected from the force that reaches the measuring roller, not from target web tension alone. Define the web path, roller arrangement, tension range, roller weight, mounting, environment and electrical interface before choosing a sensor range or model.
Tension load cell selection guide
Specify the measuring roller before the sensor model
A useful load-cell specification connects the web path and resultant force to the mechanical mounting, usable range, environment, signal conditioning and commissioning plan.
1. Define the measurement zone and roller arrangement
Start with the exact web span whose tension must be measured and the idler roller that will carry the sensing load. FMS describes web tension measurement as an indirect force measurement at an idler roller, commonly using a force sensor at each end of the roller; different roller constructions require different sensor formats.[2]
Number of sensors
Document whether the roller is supported by one sensor or two. A two-sensor arrangement divides the supported resultant between the left and right sides only when the mechanical load is distributed as intended.[2]
Machine constraints
Include roller width, shaft or flange dimensions, available mounting space, bearing arrangement and any need for a customized roller surface or dimension.[1][2]
2. Calculate the resultant load at the measuring direction
Do not equate maximum web tension with load-cell capacity. The incoming and outgoing web angles determine the force components that act in the sensor measuring direction, while the measuring-roll weight may add or subtract force depending on orientation. Erhardt+Leimer expresses the web-force components as F1 = F × cos α and F2 = F × cos β for its illustrated arrangement, with the per-cell resultant derived from those components.[3]
- Record minimum, normal and maximum web tension in one consistent unit.[2]
- Draw the incoming and outgoing web directions relative to the proposed sensor measuring direction.[2][3]
- Add the measuring roller, shaft and supported hardware weight in the installed orientation.[2]
- Calculate the expected resultant for the exact sensor arrangement, then have the selected manufacturer's application method confirm the required nominal range and allowance.[2][3]
3. Choose the mechanical format and usable range together
Capacity alone is not a complete selection. FMS lists roller type, nominal force, web path, roller weight, environment and standard-versus-custom construction as parallel selection criteria. Its documentation also distinguishes nominal force from the lower end of the specified measuring range, so both the highest resultant and the lowest useful operating point must be reviewed.[2]
Highest expected load
Confirm that the complete mechanical resultant remains within the selected sensor's permitted operating range and the manufacturer's application limits.[2]
Lowest useful signal
Check that low-tension products remain inside the sensor and amplifier's specified usable range instead of selecting only for the worst-case maximum.[2]
Environment and mechanics
Specify temperature, moisture, dust, corrosive exposure, washdown needs, hazardous-area requirements, bearing arrangement and anticipated non-measuring loads before final selection.[2]
4. Match the bridge, amplifier and controller interface
Verify excitation voltage, bridge resistance, sensitivity, wiring, channel count and signal-conditioning requirements as one interface. KRD publishes the LB60 as a 10 VDC, 2 mV/V, 350 Ω full-bridge tension detector with four rated-load grades; those values describe the LB60 and must be checked against the proposed amplifier or controller rather than assumed to be universal.[1]
- Confirm whether the receiving device accepts one sensor, two sensors in parallel, separate left-right channels or an external measuring amplifier.[4]
- Check the exact sensor excitation and full-scale signal against the controller or amplifier input documentation.[1][4]
- Record cable length, shielding, grounding, connector and routing requirements from the selected equipment manuals before installation.[4]
5. Plan calibration and acceptance before ordering
The commissioning plan should reproduce the installed force path. The FMS EMGZ321 manual separates offset compensation from gain calibration, calls for offset compensation before calibration, and describes simulating the later material path with a rope and known weight for that specific measuring system. The exact procedure remains equipment-specific and must follow the selected sensor, amplifier and controller manuals.[4]
Zero condition
Define the unloaded mechanical state used for offset or zero adjustment, including the installed measuring roller and bearings.[4]
Known-force check
Prepare a controlled calibration method that follows the real wrap path and measuring direction, using the selected equipment's documented procedure.[4]
Acceptance record
Record left, right, sum and difference values where available, then verify stable readings across the intended product and tension range.[4]
6. Prepare the data package for KRD review
For an LB60 or other KRD tension-sensor review, provide the web material, web width, tension range, measuring-roll dimensions and weight, web-path angles, roller arrangement, mounting drawings, environment, line speed, existing sensor signal and receiving controller or amplifier. KRD can then review the intended load range, mechanical configuration and interface without treating one model as a universal replacement.[1]
Sources & References
- KRD Industrial Solutions. LB60 Series Cantilever Tension Detector Back
- FMS Force Measuring Systems AG. FAQ – Web Tension and Force Sensors Back
- Erhardt+Leimer GmbH. ELTENS Web Tension Measuring System Back
- FMS Force Measuring Systems AG. EMGZ321 Series Installation Manual and Operating Instructions Back
FAQ
Can load-cell capacity be selected from maximum web tension alone?
No. The force at the sensor also depends on incoming and outgoing web angles, the measuring direction, measuring-roll weight, orientation and whether one or two sensors support the roller. Use the exact manufacturer's application method for the proposed arrangement.
Should a web-tension measuring roller use one load cell or two?
It depends on the roller and machine design. A conventional roller may use one sensor at each end, while cantilever, flange and other arrangements can use different sensor formats. The support and force path must match the selected design.
Can any tension load cell connect to any tension controller?
Do not assume compatibility. Verify excitation voltage, bridge resistance, sensitivity, wiring, number of channels, signal conditioning and calibration functions against both the sensor and controller or amplifier documentation.
What information should I send KRD for load-cell selection?
Provide the material, web width, minimum and maximum tension, web-path drawing, measuring-roll dimensions and weight, roller arrangement, mounting space, environment, existing sensor signal and the receiving controller or amplifier model.
Request a web tension load-cell selection review
Share your tension range, web-path angles, measuring-roll dimensions and weight, mounting layout, environment and controller interface. KRD can review the load range and sensor configuration for the real machine.