Open-Loop or Closed-Loop Tension Control?

So, you need a new tension control system, however, do you know which one is the right choice for your needs? From open-loop, to closed-loop control and everything in between, there is a range of systems available, and the choice can be both confusing and overwhelming. This blog will explain to you the difference between diameter calculation and direct load cell feedback control systems, so you can choose the best system for your application.

Dover Flexo Electronics are leaders in the tension control field, offering open and closed-loop tension control systems that are automatic. Their products suit a range of budgets so you can find one to suit your web processing, converting, or printing needs. Their EasyWeb Torque Controller is an outstanding open-loop system, as you can directly control the torque whilst adjusting the web too. Alternatively, their SteadyWeb 6 Tension Controller is its closed-loop counterpart. However, what is the difference? It quite simply is the difference in how each of these systems feedback.

Closed-loop controllers use feedback tools to be able to measure the variable and put that value into the control, through the technology of a comparator circuit. It tells the controller to adjust its tension for the web throughout the output, so it’ll match what your desired tension input was as it works.

Open-loops work slightly differently, using a continuously adjusting the tension, but this time working from the calculated difference in roll diameter, during its unwinding, as gets smaller or larger. This can come from a variety of means, like encoders, ratios, and sensors, it needs a variable apart from its direct tension measurement. This isn’t as precise as closed-loop systems, but this is accurate enough in certain applications and scenarios.

Therefore, the benefit of closed-loop systems is that they’re the most accurate compared to open-loop controllers, as it reacts to the system and its changes immediately even with the amount of noise it makes in some cases! Closed-loop controllers are ideal for machines that have a low tolerance to waste, and when you’re using expensive materials. However, one of its downfalls is that they are more costly than open-loop systems which is something to consider. So, depending on the job and accuracy you require a closed-loop system might not be needed, if a bit of tension deviation is okay, an open-loop system might be the better choice.

Here at Swallow Machinery, we supply a range of Dover Flexo Electronics products, from tension transducers and load cells to torque controllers, tension indicators, and amplifiers. They’ve got high-quality products that perform specific functions. Click here to take a look at our range. Our team can work with you and your requirements to find the right solution and system for your needs, contact us here!

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