The Importance of Monitoring the Tension of Fibers

Posted by Maureen Redmond on Sep 28, 2020 3:14:04 PM

In upstream composites production processes, it is often necessary to control a fiber 

or a band of fibers to an optimum tension value. However, identifying the correct tension is often overlooked, and production processes still utilize tensioning systems which were developed decades ago without much consideration.

If the starting tension at the creel is not controlled properly, then the final product may be constructed of fibers with varying tension. As a result, it will not fully utilize the strength of all fibers equally. This can degrade the mechanical properties of the final product.



In other cases, we often see applications where tension on fibers is so high that it causes filament damage. This can also degrade the quality of the final product.

To avoid these issues and understand the optimum tension for each application, we often recommend the DTH tension sensor, a mounted low-cost fiber tension sensor that allows you to monitor the tension in fibers or web material.


How a DTH sensor helps

The DTH tension measurement can be used to control or monitor the tension for any type of fiber, including carbon fibers, glass fibers, aramid fibers, ceramic fibers, and fiber optics.

In production scenarios where it becomes too costly to incorporate a tension sensor for each fiber to control tension, the DTH can be used to simply monitor the tension. The DTH is compact, so moving from tow to tow for individual tension verification is also an easy task. Once the optimum tension setting is determined, a lower cost mechanical tension control system with the correct tension control range can be incorporated to improve the final product.

For routine maintenance or tension monitoring, we recommend the mountable DTH, since handheld tension meters can be dependent on the operator’s skill or experience.


Application Examples

Below are some examples of applications where we’ve seen firsthand how the DTH sensor made a difference:

Carbon fiber weaving: Weaving creels for carbon fiber are typically mechanical systems. We have seen DTH tension sensors used to periodically check the tension of each position as they fluctuate over time.

Carbon fiber production: DTH sensors can be incorporated into the PAN precursor creels to monitor and control tension at the start of the carbon fiber production process. This helps keep the resulting carbon fiber quality consistent. The DTH output can also be used to alarm operators of a tow break or high tension.

Unidirectional prepreg manufacturing: Incorporating DTH sensors in the creel enables adjustment of positions to generate consistent tension throughout the web for a uniform sheet output. In some cases, the edges require differing tension, and the DTH sensor enables the monitoring and adjustment required to accomplish this.

Towpreg manufacturing: The DTH can be installed in let-off creels for towpreg manufacturing to provide accurate tension measurement of the beginning of the process. The consistent tension among tows allowed for consistent wet-out and width of the fiber.

Pultrusion manufacturing: The DTH enables precise monitoring and adjustment of the let-off creel. This contributes to consistent tension among fibers, which helps improve the mechanical characteristics of the final pultrusion.

Carbon fiber friction coefficient: The DTH has been used in laboratory systems to calculate the friction coefficient of the carbon fiber.



The DTH Tension Sensor offers a wide selection of options:

Roller widths from 2.5mm to 610mm, Capacity from 50grams to 20000grams



                Narrow roller DTH                                Wide roller DTH                                              Web DTH                          


Can be supplied as sensor only for utilization of analog output signal and incorporation into existing PLC for control or into chart recorder for monitoring, or can be used in combination with TAQ data transmission modules which we produce..

Some of the TAQ data transmission modules available are shown below, or other custom solutions are available based on your requirements.


TAQ3000 - Digital display only

Available in single position units as well as multiple position units.  The display is compact and monitored tension can be seen local to the sensor, making it convenient for measuring the fiber tension in a process.


TAQ4000U - USB to PC

These units display and log tension to a PC, a dedicated HMI, or USB stick.


          PC data logging example                                               Single HMI for multiple sensors


For further detailed information on the DTH and TAQ systems, please visit this page. Download the DTH/TAQ datasheet here.

If you have any questions about this product or would like other expert recommendations for your fiber production process, give Izumi International a call at 864.288.8001 or contact us online. We’d love to help you find the most effective equipment for your business!



Topics: Carbon FIbre, Tension Control