Tension Control 101

Tension control and web handling are general terms.  This blog is about the basics of tension control. 

There is a simple formula: Tension = Torque / Radius

The Tension is the force of the material as it goes through the tension zone.  The Torque is the force applied to the roll or spool.  The Radius is half the diameter of the roll.  On an unwind, as the roll get smaller (the radius is decreasing), you must decrease the torque proportionally in order to maintain a constant tension.

There are three types of tension controls: manual, open loop, and closed loop. 

Manual System Control

On a manual system, the torque is constant so the tension will rise as the diameter of the roll decreases.  The control could be a power supply for a magnetic particle brake, a regulator for a pneumatic brake, or a leather strap or mechanical brake with a thumb knob.  For some applications, this works fine.

Open Loop Control

On open loop control, there is a measurement for the diameter of the roll which can be achieved in a few different ways: diameter sensor (either laser or ultrasonic), follower arm, or a calculation from tachometer input from spindle and line speed.  The diameter input is utilized by the control to send an output to the brake (torque) via an amplifier or current-to-pressure transducer.  There is no feedback from the material which classifies the control as open loop.  It automatically adjusts the torque as the roll gets smaller in order to maintain a fairly constant tension.

Closed Loop Control

There are two types of closed loop controls: dancer and load cell.  In dancer control, the feedback comes from a potentiometer on the dancer arm.  The proper way to load a dancer is with an air cylinder.  The force on the dancer sets the tension.  The control tries to maintain the position of the dancer arm.  It will increase the brake if the dancer lowers and decrease the brake if the dancer rises.  Dancers are great for intermittent motion, badly out of round rolls, and splicing on the fly.  However, this type of closed loop does not allow for a read out in tension which is vital for precise tension control.

Our Favorite

By far the best tension control is utilizing closed loop load cell (tension sensors, tension transducers…) control.  The load cell signal is utilized by the control to provide output to the brake via an amplifier or pneumatic converter.  As mentioned previously, this is controlling the torque of the brake.  The load cells will monitor the tension of the material which gives the operator a pound’s tension value to determine how the process is running.  The control will maintain the set point tension by reducing the output to the brake as the roll gets smaller. 

The Reasoning

Because of the set point and feedback from the load cell, this is the most stable and repeatable system for controlling tension on a web handling or continuous processing line.

Remember, this is tension control 101.  There are many factors to determine the correct solution for each application.  Luckily, Grosel Industrial Sales has over 40 years’ experience to assist.  Please contact us with any questions.

Tags: Tension Control, Web Handling, Converting, Closed Loop Tension Control, Load Cells, Tension Transducers, Tension Sensors, Application Expertise, Grosel Industrial Sales

Reliable, Durable, and Long Lasting: RDL Coatings

Ray and Donna Lopez, owners of RDL Coatings, first met in 1996 while working together in the surface enhancement/plasma spray coating industry.

Ray began his journey in this industry by working as a sand blaster. Within only one year, he quickly advanced throughout the various stages in the production process.  His technical expertise paired with his hands-on knowledge laid the foundation for him to go into Technical Sales. Here, he earned many awards and continued to grow his talents.  Heading up special accounts and complex applications, he earned the title of Regional Sales Manager. 

Meanwhile, Donna led the customer service department as Supervisor.  She spent a significant amount of time in the plant learning the process and going onsite to customer locations. These experiences fostered her deeper understanding of the various production problems across different industries.  Having a thorough understanding of every facet of the coating industry, Ray and Donna eventually opened their own coating company in 2016. 

RDL Coatings is an applicator of industrial plasma/thermal sprayed coatings.  They offer an extensive line of surface coverings to combat various production problems such as sticking, build up, slippage, wear, tracking, web snags, and more.  RDL’s protective coatings offer a more long-term solution as opposed to utilizing tape, cork, and other temporary “fixes”.  The commonly coated parts include:

  • Rolls (Idlers, Pull, Guide, Nip)
  • Fingers
  • Pans
  • Guide Rails
  • Shafts
  • Plates
  • Mandrels
  • Tubes
  • Chutes

RDL’s extensive history within the industry has guided them to diagnose and remedy most production problems quickly and efficiently.  Being a family-owned company, the workforce at RDL is bound by trust, dedication, and common goals.  The pride they take in the relationships they maintain with their customers is at the forefront of their business model. For more information, please contact us or click here to find out how you can “Arm Yourself with The Best!”

Tags: RDL Coatings, Paper, Converting, Rubber, Adhesive, Non-woven, Plastic, Printing, Plasma Sprayed Coatings, Traction Coatings, Release Coatings, Thermal Spray, Grosel Industrial Sales

Tilt-Lock Increases Capabilities

Tilt-Lock is your one-stop headquarters for a wide selection of roll handling equipment. They provide lifting devices that seamlessly incorporate simplicity and functionality to deliver the best long-term results.

Their focus is offering reliable, cost-effective solutions. These solutions feature roll handling equipment that will prevent injuries, increase productivity, save time, and reduce product damage. Tilt-Lock products are designed, engineered, and built with you, our valued customer, in mind.

Customers realize that off-the-shelf products are not a good fit for some applications. Tilt-Lock specializes in custom products to provide the optimal result for each project. Our goal is to understand the customer’s needs and provide a material handling solution to improve the process.  Please contact us or click on the link below for more information:

Tilt-Lock Custom Material Handling Capabilities

Tags: Tilt-Lock Roll Handling, Custom Material Handling, Grosel Industrial Sales, Roll Handling, Converting