Accurate tension a key to quality

Web tension measurement and control is essential to achieve high levels of quality and productivity. ABB systems are providing the reliability and performance required

Knowing what the tension actually is at various key points in a machine or process line is fundamental to ensuring high quality and efficient operations in all types of web converting processes. Web tension measurement and control are equally important in converting as well as film, foil and textile manufacturing.

Essentially it is the ability to dynamically control the mechanical tension in any material being processed at any point in the process phase while it is accelerating at constant speed or decelerating. It is required in any web handling and converting machinery in order to achieve production with both high and consistent quality; high productivity with the minimum of unscheduled production stops; and to increase the machine speed.

Important requirements for reliable web tension measurement and control include long-term stable sensitivity – the secret to good and reliable repeatability; robust construction in order to withstand real production envirionments; recalibration-free load cells minimising maintenance costs; and user friendly to minimise the time needed for set-up and commissioning.

Improved productivity

Web tension as a process value is measured and controlled to protect machines and machinery and leads to improved productivity and product quality. Tension that is too high can cause damage to deflector rolls and roll bearings resulting in unplanned machine stops; stretching of the web, change in the width and ultimately snapping of the web; in addition to ‘wound roll’ defects such as crushed cores, starring and edge cracks. On the other hand, too low tension often results in defects including web wrinkles where the web isn’t stretched sufficiently over deflector rolls; web skid marks coming from the rolls, usually because the web isn’t able to transfer sufficient torque to idle rolls or pick up torque from driven rolls; poor reel quality causing ongoing problems in the follow on processes and the possibility of telescoped reels. Unstable tension is caused by length and width variations in slitters and sheeters or curled material in laminating processes.

ABB provides high performance systems based on Pressductor technology giving tension measuring options and performance superior to any other technology. To enhance its advantages an updated series of digital tension electronics – the PFEA11Xseries has been released.

Accurate and reliable

Customers have expressed total confidence in the performance of the load cells which has given them the peace of mind from always knowing how the lines are running at any given time.

Many have replaced competitor’s systems with the ABB solution because of the many advantages including the fact that: “the load cells are designed to be installed and left alone to do their job; after two years they are performing flawlessly and we are planning to install further applications.”

In addition, when the web breaks it is not necessary to spend several hours recalibrating the load cells or replacing them because they have failed so the lines are quickly up and running, minimising downtime. The PFEA digital electronics are easy to configure, program and troubleshoot and users benefit from improved data via the display.

Further comments from satisfied customers include: “ABB load cells deliver very stable tension measurement over time; our customers – the end-users – believe in our extensive experience with Pressductor load cells – we can convince them that they are the best; the display is easy to operate and there are many good functions to take advantage of; the robust load cells are working really well in this severe production environment with high humidity and significant differences in temperatures; Pressductor PillowBlock load cells stand for reliable and stable measurement.”

From the paper industry comes this observation: “in this rugged environment you expect that the products and in this case the load cells can take an impact without breaking, for example when the maintenance people climb up and down the machine – you can step on a Pressductor load cell without breaking it – which is a big advantage for us.”

ABB Limited, Force Measurement

T: +44 (0)1925 741 514

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