Mastering Web Tension: A Technical Guide to Brakes in the Paper Industry

In the high-speed world of paper manufacturing, consistency is king. From the initial unwind stand to the final rewound roll, maintaining precise web tension is one of the most critical factors influencing product quality and operational efficiency. Inconsistent tension leads to costly problems like web breaks, wrinkles, and registration errors. The unsung hero in this process is the industrial braking system, which provides the control and reliability needed to master web tension.

This guide explores the vital role of brakes in the paper industry, focusing on how modern pneumatic braking technology offers the perfect solution for demanding tension control applications.

The High Cost of Poor Tension Control in Paper Mills

When the tension on a paper web fluctuates, the consequences can halt production and create significant waste:

• Web Breaks: Sudden tension spikes can snap the paper web, leading to costly downtime for re-threading the machine.
• Wrinkling and Creasing: Insufficient tension allows the web to wander or sag, causing wrinkles that render the final product unusable.
• Telescoping Rolls: Inconsistent tension during rewinding can cause layers to shift, resulting in “dished” or “telescoped” rolls that are difficult to handle and process further.

The Unwind Stand: The Heart of Tension Control

The primary point for tension control is the unwind stand, where the large parent roll is unwound into the processing line. A braking system is mounted on the roll’s shaft to apply a continuous, controlled “back-torque.” As the roll’s diameter decreases, its rotational speed must increase to maintain a constant web speed. The braking system must dynamically adjust its torque to ensure web tension remains perfectly constant throughout the entire roll.

Pneumatic Caliper Brakes: The Industry’s Choice for Finesse and Power

For paper industry applications, pneumatic caliper disc brakes have become the industry standard. They offer a unique combination of features perfectly suited for tension control:

• Proportional Control: The braking force is directly and linearly proportional to the input air pressure. This allows for extremely fine and responsive adjustments via a simple pressure regulator, easily integrated into a closed-loop PLC system with tension sensors.
• Excellent Heat Dissipation: The open design of a caliper and disc system allows for superior air cooling, efficiently dissipating the heat generated by continuous braking. This prevents brake fade and ensures consistent performance.
• Modular & Scalable: Multiple calipers can be mounted on a single disc, allowing for a wide range of torque outputs to handle different roll sizes and machine speeds.

Engineered Braking Solutions for Your Paper Line

We offer specialized pneumatic brakes designed to optimize your paper processing line’s performance and safety.

For Dynamic Tension Control: CQP & QP Series Pneumatic Caliper Brakes

Our CQP and QP Series brakes are the workhorses of web tension control. Their modular design and responsive performance make them ideal for the dynamic demands of unwind stands.

• Linear Torque Response: These brakes provide a braking torque that is directly proportional to the supplied air pressure, typically within a range of 0 to 7 bar. This linearity is crucial for precise PLC-based closed-loop tension control.
• Scalable Performance: A single disc can be fitted with 1 to 4 brake calipers, allowing the maximum torque to be precisely matched to the machine’s requirements.
• Easy Maintenance: Pad replacement is straightforward, minimizing machine downtime.

Discover the technical specifications for our high-performance tensioning brakes on the CQP & QP Series Pneumatic Brakes product page.

For Safety and Holding: SP Series Pneumatic Fail-Safe Brakes

While tension control is primary, safety is paramount. The SP Series provides this critical safety layer with its fail-safe design.

• Fail-Safe by Design: These brakes are spring-applied and air-released. In the event of an air pressure loss or an emergency stop signal, powerful springs instantly engage the brake, safely stopping the web and holding the roll stationary.
• Critical Applications: Ideal for emergency stopping systems and for securely holding rolls during splicing operations or maintenance, preventing accidental unwinding.

Ensure the safety of your machinery and personnel. Learn more about our SP Series Pneumatic Fail-Safe Brakes here.

Quick Selection Reference Table

Conclusion

Investing in a high-quality braking system is not an expense; it’s a direct investment in the quality of your product and the efficiency of your operation. By selecting the right pneumatic brakes for your paper line, you can significantly reduce waste, minimize downtime, and produce consistently high-quality rolls.