In flexible plastic film converting, web tension is one of those topics that looks simple from the outside.

You set a value, the machine runs, the film moves from unwind to rewind.

But anyone who has spent time near a converting line knows the reality is different.

A few Newtons too much, and the film starts stretching.

A little instability, and wrinkles appear.

Poor control during acceleration or deceleration, and roll quality starts to suffer.

In thin films, even small tension changes can become visible on the final product.

That is why DMS Converting do not see web tension only as a control parameter. We see it as one of the key engineering points that directly affects production stability, material waste, roll quality and operator confidence.

There is no single tension control method that is perfect for every application. The right solution depends on the film type, thickness, machine speed, roll diameter, process sensitivity and the final product requirement.

In our converting machines, we generally work with several different tension control approaches.

1. Loadcell-Based Direct Web Tension Control

This is one of the most precise methods because the web tension is measured directly.

Loadcells continuously read the actual force on the web, and the control system adjusts the brake, motor or drive accordingly.

For applications where stable and repeatable tension is critical, loadcell control provides a strong advantage.

We usually consider this method for high-quality rewinding, wide web applications, thin films, sensitive materials and processes where roll quality must be consistent from the first meter to the last meter.

The biggest advantage is simple: we are not estimating the tension. We are measuring it.

2. Dancer Control

Dancer systems are very useful when the process needs a mechanical buffer.

The dancer absorbs web speed variations and helps maintain stable film flow, especially during acceleration, deceleration or intermittent motion.

One important point is that dancer tension is adjustable. By changing pneumatic pressure, cylinder force or mechanical settings, the system can be adapted to different films and production conditions.

In some machines, the dancer does more than control tension. It also gives the machine a more forgiving behavior. This is very valuable for operators, especially in processes where film behavior changes from roll to roll.

For flexible packaging films, dancer control is often a practical and reliable solution.

3. Servo Gear Control

In some applications, we use servo gear-based solutions where axes are electronically synchronized.

This allows precise speed ratio control between machine sections.

Servo gear control is especially useful when different rollers or units must follow each other with high accuracy. Instead of only reacting to tension changes, the machine can be designed to move in a more coordinated way.

This method becomes important in applications where repeatability, registration, synchronized motion or high dynamic response is needed.

It is not always the cheapest solution, but in the right application, it gives excellent control performance.

4. VFD Closed-Loop Control

For many converting lines, VFD-based systems are still very strong and cost-effective when designed correctly.

In closed-loop VFD control, the system can work with feedback such as speed, torque, current and diameter calculation.

As the roll diameter changes, the required torque also changes. If this is not managed correctly, tension will not stay stable during the roll build-up or roll decrease.

By following diameter and using torque/current/speed feedback, the drive system can provide better control and more stable winding or unwinding performance.

This approach is especially useful when we want a balance between performance, reliability and investment cost.

5. VFD Open-Loop Control

Not every application requires a complex control system.

For some processes, open-loop VFD control can be enough if the machine design, film type and production speed are suitable.

In this case, we can still work with current, torque and speed control logic, together with diameter tracking. But since there is no direct feedback from the web tension, the system depends more on correct calculation, proper commissioning and process experience.

Open-loop control can be a practical solution for less sensitive applications, but it must be applied carefully. The important point is knowing its limits.

A simple system is not a weak system if it is used in the right place.

In flexible plastic film converting, good engineering is not about using the most complicated method. It is about choosing the right method for the real production condition. Because at the end of the day, tension control is not only about keeping the film tight.

It is about keeping the process under control.