Web Coating Tension Control

Web coating systems are used in the manufacture of various products including labels, tapes, coated vinyl, sandpaper, flexible packaging, paper goods, circuit boards, foil and decorative laminating.

While a wide range of coating methods may be used, generally most processes involve the transfer of a liquid to a flexible web while in motion. A typical coating system consists of a roller design or set of nozzles used to precisely apply the coating to the web, followed by a drying process.

Gravure-Type Coating Process

As the web is pulled through the coating & drying zone, there are many variables that can cause coating problems such as temperature change, drift, coating thickness, vibration, impression roll gap, debris and roll speed.

The ability to control web tension during and after coating is of particular importance. If a web does not have proper tension control, it is almost impossible to maintain a steady speed and lay-down rate as the substrate transits through the coater. This can result in coating defects or problems with the coating’s ability to adhere to the web properly during take-up.

Some benefits of tension control in web coating applications include –

• Uniform Coating Application: Proper tension control ensures the web (e.g., film, paper, foil or textiles) remains flat and stable as it passes through the coating station. This prevents wrinkles, stretching, or uneven coating thickness, resulting in a consistent, high-quality finish.
  
  
• Improved Material Handling: Maintaining optimal tension prevents the web from sagging or snapping. This reduces the risk of tears, breaks, or misalignment, which can halt production and waste materials.
  
  
• Enhanced Speed and Productivity: With precise tension, the system can operate at higher speeds without compromising quality. Stable tension minimizes downtime caused by web breaks or adjustments, boosting throughput.
  
  
• Reduced Waste: Inconsistent tension can lead to defects like streaks, bubbles, or uncoated patches, increasing scrap rates. Effective tension control minimizes these issues, lowering material waste and costs.
  
  
• Better Registration Accuracy: In multi-layer or patterned coatings, tension control ensures precise alignment between layers or sections. This is especially important for applications like flexible electronics or printed packaging.
  
  
• Equipment Longevity: Excessive or erratic tension can strain rollers, motors, and other machinery components. Controlled tension reduces wear and tear, extending equipment life and reducing maintenance costs.
  
  
• Adaptability to Material Variations: Different webs (e.g., thin films vs. thicker substrates) require specific tension levels. Advanced tension control systems can adjust dynamically, accommodating a range of materials without manual intervention.
  
  

No matter the coating application, maximum productivity and minimum waste is the final goal. DFE offers the highest quality tension sensing transducers and controllers to achieve both consistency and reliability in your coating process.

Typical tension control solutions incorporate:
• A closed-loop tension controller such as the SteadyWeb™ 6
• A load cell such as the Tension Roll® Transducer
• A Pneumatic Brake, Magnetic Particle Brake, Clutch or Motor Drive System

Customers integrating tension control with a PLC most often utilize:
• A load cell signal amplifier such as the TA1 TrueTension™ Amplifier
• A load cell such as the Tension Roll® Transducer, a pair of convertible load cells such as the Model C Series Transducers or Under Pillow Block Transducers such as the Model F Series