Web Tension Control Systems
A web that isn’t held at the right tension will tell you about it, in wrinkles, breaks, weaving, drifting registration, and scrap that climbs the moment you try to push the line faster. Tension control is the layer between a machine’s individual sections and the finished roll it produces. Get it right, and the line runs at its top practical speed with a consistent, high-quality result. Get it wrong, and you spend years fighting a problem that looks mechanical but usually isn’t.
At AMS, web tension control is an engineering discipline we take seriously from the first site visit to the last tuning pass.
What Is a Web Tension Control System?
A web tension control system regulates the speed relationship between the different sections of a converting line: unwind, process, rewind. That keeps the material at a consistent tension no matter what speed the machine is running, including through acceleration and deceleration. It does this by trimming each section’s speed reference based on feedback from a dancer roll or a load cell equipped tension roll. Dancers stay in physical contact with the web, which makes them well suited to lighter or more fragile products where a load cell alone might miss a web that’s gone slack. Load cells, on the other hand, give heavier, low-stretch products like linerboard a direct, continuous force reading. A good tension control system is a result of the algorithm and the process expertise of the engineer who tuned it. That’s why tuning sits at the center of how AMS approaches every project.
Web Tension Control System Services
Every tension control solution AMS delivers starts with understanding the specific application: the products that will run on the line, the speed range required, the mechanical characteristics of each section, and how the machine behaves during acceleration, deceleration, and steady-state running.
Some tension feedback devices come bundled with a built-in control algorithm designed for general use. We build the control loop ourselves instead, tuned specifically in the PLC or drive controller for that machine and that product. As a result, we have full visibility into how the system responds and can account for that machine’s particular mechanical behavior. A project might call for retrofitting an existing drive and control platform, or building a new system from the ground up. Either way, we understand our tension control systems before we specify them.
Tension Control Systems for Paper and Web Converting
Tension requirements vary widely by product. Linerboard is strong and largely without stretch, wound tight to maximize footage per roll, on winders that can run 5,000 to 6,000 feet per minute. Commercial towel is wound tight for a similar reason: fewer dispenser refills, and might transfer rolls at 1,500 to 2,000 feet per minute while speeding up to 2,500 feet per minute in the middle of the wind. Kitchen towel is embossed and wound looser and fluffier by design. Tissue sits in between, with stretch characteristics that vary by grade, often transferring around 2,000 feet per minute.
A tension control system tuned for one of these products rarely performs well on another without real engineering behind the change. The same principles apply to film and nonwoven converting lines, anywhere a web is unwound, processed, and rewound.
Tension problems often start at the unwind. Unwind tension control has to account for the parent roll, which begins at its largest diameter and highest inertia, and the control system has to compensate as that diameter shrinks and the roll’s inertia drops through acceleration, running speed, and deceleration. When it doesn’t, the problem carries into every section downstream, showing up as breaks, wrinkles, or inconsistent roll density.
Built for the Speed Your Line Needs
Our work on a tension control system begins the same way every project does: with a thorough understanding of the machine, the product, and where tension zones exist across the line. We tune each loop with a full picture of how the machine behaves at startup, at speed, and everywhere in between.
Key Takeaways
- A tension control system is only as good as the engineer who tuned it. Tuning sits at the center of how AMS approaches every project. It’s built around how your specific machine and product behave.
- AMS builds tension control systems for the machine. Every project starts with understanding the product, the speed range, and the mechanical characteristics of each section.
- We build and tune the control loop in-house. That gives us full visibility into the system and lets us account for acceleration, deceleration, and steady-state behavior specifically.
- Product characteristics drive the approach. Linerboard, commercial towel, kitchen towel, and tissue all wind differently. As a result, a web tension control system has to be tuned for the product running.
- The payoff is speed you can use. A well-tuned tension control system means the line can run at its top practical speed. Wrinkling, breaks, and scrap stop eating into the gain.
How AMS Approaches Tension Control
Tension control is a means to an end. The end is a line that runs at the speed it’s capable of, that produces consistent, high-quality rolls, and that your team can trust through every changeover. That’s what we build for.