Web Guiding and Tension
Rollers and Web Tension: A Brief Overview
A
s a perfect complement to tension control equipment in a process line, rollers play a crucial role in maintaining web tension. They provide support, guide and drive the web material as it moves through the process. Rollers can impact web tension in at least four significant ways. Firstly, proper roller placement prevents web sagging, wrinkling or breaking. Secondly, lower inertia rollers accelerate and decelerate faster, reducing tension fluctuations. Thirdly, rigid rollers minimise web deformation, ensuring consistent tension. Finally, the roller’s surface and material affect friction, influencing web grip and tension.
CASE OF STUDY
A few months ago, one of our customers contacted us for technical advice on a project; a 4m wide pressure roller to be installed on a plastic film production winder. As a leader in aluminium low inertia rollers, we first discussed with our engineering department a tailor-made solution based on our Alveotube profile. Indeed, the Alveotube characteristics allowed us to manufacture wide width rollers with low inertia. However, in this specific large plastic production process, wrinkles
remained the ‘bête noire’. To maintain a consistent and adequate pressure during the winding of large plastic films whilst keeping low inertia to reduce web tension, we opted for a different material and designed carbon fiber rollers. Indeed, for this application, we concluded that carbon fiber rollers would be more efficient for web tension in this process line than aluminium rollers, primarily due to their superior strength-to-weight ratio, ultra lightweight and stiffness.
We also offer custom-made carbon fiber rollers. Our only standards are the inside diameter of the roller. We have chosen the filament winding process for different technical reasons. This process provides greater design flexibility, material efficiency, mechanical property and production control. Size and length: Filament winding can produce rollers with large diameters and longer lengths thanks to the continuous nature of the process.
Excellent mechanical properties: Despite being ultralight, carbon fiber rollers show high strength and stiffness-to-weight ratios, making them suitable for demanding applications. All these advantages make them a preferred choice for applications requiring high performance and complex geometries.
Material efficiency: Filament winding precisely controls fiber placement, maximising material utilisation and achieving high strength-to-weight ratios. Consequently, less material is wasted in the filament winding process, as fibers are applied only where needed.
Mechanical properties: With precise fiber orientation and controlled resin impregnation, filament wound components often show high tensile, compressive and flexural strengths. Filament winding can also produce rollers with enhanced impact resistance by varying fiber angles and resin systems. Design flexibility: Filament winding allows for the creation of complex, asymmetrical and varying wall thickness profiles. This is crucial for rollers with specific load-bearing requirements or intricate geometries. Additionally, this process offers greater flexibility in fiber orientation and resin content, enabling tailored mechanical properties for different roller sections. Production control: Filament winding processes allow for real-time monitoring of parameters such as fiber tension, resin content and winding patterns, ensuring consistent product quality. Adjustments can be made on the fly to optimise the winding process based on performance requirements. To conclude, it is important to note that, depending on process needs, productivity and quality requirements, the choice of roller material could be a key issue. Both aluminium and carbon fi ber rollers have numerous common features and are highly benefi cial for reducing tension on a web in a process line due to their lightweight, stiff ness, energy effi ciency and durability. However, carbon fi ber rollers may not be the best choice for every application. They can be more expensive than aluminium rollers and their stiff ness may not be ideal for very delicate webs. Sometimes, on the contrary, it is preferable to use a carbon roller, even at a higher price, but with the assurance of a higher-quality fi nished product and reduced wastes, especially for long length rollers. To be sure that you make the best choice, it is advisable to consult an expert to carry out your project. They will be able to design a tailor-made product to meet your process requirements.
48 September 2024
www.convertermag.com
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