Torque Sensing Control System
What is Extended Range?
Analog in a Digital Age
Torque Sensing Control System™
Open loop tension control is more accurate and precise than ever before
For the first time ever in an open loop control system, you get a precise, reliable tension reference that operators can use to ensure consistent, high quality production runs without load cells or a dancer.
Patent pending technology allows easy integration into existing machines as well as new machine builds.
Customize your TSC™ packages based on your needs and the products you currently have. TSC™ components can include the U4 Tension Controller, V or CS Series Brake, TS Torque Sensor, US4 Ultrasonic Sensor or Proximity Switches, M4 Meter, and an MPC4 I to P Converter
The TSC™ is ideal for applications where:
- The machine cannot accommodate load cells or retrofits (space limitations, costs, etc.).
- There is no defined web path or web is traveling directly from unwind roll into the process.
- The web cannot be contacted after unwind by rollers or requires minimal roller contact (coating, films, foils, etc.).
- Multiple unwind stands that each require cost effective, simple control, and a simple web path (sheeters, laminators).
- Existing open-loop system, but want to improve consistency and quality of your production.
- Utilizing a PLC or similar system and want to control torque with minimal modification and effort.
A customer recently asked us how our load cells compared to other manufacturers that promote “extended range load cells”. These extended range load cells utilize a 10V excitation with the claim that by using a higher excitation you get a more sensitive tension signal. For reference, Montalvo’s load cells utilize a 5V excitation.
So the idea is that for a 100 lb load cell with a 5V excitation, you would get 125 mV of output, whereas with an “extended range” load cell you would get 250 mV of output due to the 10V excitation. The sales pitch is that with double the input, you get double the output and thus have a more sensitive load cell for detecting any changes in tension.
Unfortunately the reality is that this does not affect the sensitivity of the load cell.
Mathematically, sensitivity is equal to Change in Input divided by Total Output (S=CI/TO)
So in our two examples:
Example A: 125 mV / 5 V = 25 (mV/V)
Example B: 250 mV / 10 V = 25 (mV/V)
Increasing the excitation voltage doesn’t change the end result at all. Also note that this value is independent of the amplifier used, so even using a more sensitive amplifier will not have an impact on this.
When choosing the best load cell for your application focus on quality, true performance, and the support you will receive, and don’t be fooled by the myth of “extended range”.
BWC Blog: Analog Meters Still Have Their Place
The benefits of analog in a digital age.
While much machine information today is displayed with digital meters, analog meters still have their place in the industrial world. One such application is the display of tension in a running web.
The tension on the web is affected by many mechanical factors in the process. When unwinding a roll of material, the quality of the roll itself is a major factor. If this roll is not perfectly concentric, which is usually the case, this will cause speed differences which will result in tension differences. The same applies to worn air shaft journals, safety chuck journal seats, as well as worn core chucks.
Other factors can be worn bearings, the web slipping on rollers, vibration due to non balanced rolls, worn gears or unstable drives. Some of these problems are easy to correct but many are not. Many do not have a major impact on product quality.
Since the tension is measured by highly sensitive and accurate load cells, these mechanical issues will be displayed as fluctuations in tension. In high speed applications, the refresh rate of a digital display or the inherent dampening of an analog meter will smooth out these fluctuations and give a good indication of the “average” tension.
In slower speed applications, these fluctuations will be much more pronounced and it can be very difficult to determine what the “average” tension is. One advantage of the analog meter in this situation is that it can be used to troubleshoot the problem. For instance, if the tension fluctuation is in sync with each revolution of the unwind roll, this will obviously indicate where the problem lies. It will then be easy to determine if it is a worn component that can be corrected or a non concentric roll which you may have to live with. Digital meters, on the other hand, will not show an easy to read “trend”.
Another advantage of the analog meter is that it is very easy to dampen. Simply connect an electrolytic capacitor to the connector of the meter. Any value between 100 and 300 microfarad should work. Just be sure to connect the positive of the capacitor to the positive of the meter. See Drawing.