BOOK_CONTENT
From Vacuum Deposition onto Webs, Films, and Foils

Overview

Winding webs in vacuum is different from winding webs at atmospheric pressure for the obvious reason that in vacuum there is, in effect, no air. The effect of this is that there is no boundary layer of air to be dragged along by the web to act as a lubricant when the web travels over rolls. There is also no air to become entrained as the web is rewound into a roll. Without this air layer, the rewound roll will always be harder wound in comparison to air wound webs. This is true even with only a small amount of tension used on the web during rewinding. Also without this air, acting as a lubricant, there is the opportunity for micro-scratches to be put into the web or coating as the web travels over rolls in hard surface-to-surface contact. The lack of air and hard roll will mean that, once rewound in vacuum, any web profile problems will become clearly apparent.

It has often been said that a good winding system can help minimize the problems caused by poor quality film whereas a poor winding system is likely to add additional winding problems.

23.1 System Design

In general, the manufacturer building the vacuum system will design the winding system. The vacuum system will often be separated into two separate zones, the winding zone and the deposition zone. One aim tends to be to minimize the chamber volume and so the winding system will be made as compact as possible.

Copyright William Andrew, Inc. 2007 under license agreement with Books24x7

Products & Services
Web Cleaners
Web cleaners are designed to remove dirt, dust, chaff, loose fibers, additives, or powders from sheets, panels, rolls or webs.
Web Winders, Rewinders, and Unwinders
Web winders, web rewinders and web unwinders are used for winding, rewinding, and unwinding webs made of paper, film, foil, nonwovens and textiles.
Core Shafts and Mandrels
Core shafts and mandrels (air shafts) are used to handle winding reels in the processing of web-fed materials.
Metal Coil Winding and Unwinding Equipment
Metal coil winding and metal coil unwinding equipment is used to process continuous lengths of metal, or metal wire, sheet or foil in converting, coating, sheeting, and manufacturing applications.
Web Dryers
Web dryers are devices which dry webs, rolls, and other continuous materials.

Topics of Interest

24.1 Metallizers If one looks back at metallizers of ten or twenty years ago and then at the current design of metallizers, it is possible to extrapolate the progress and hence it is possible to get...

Chapter List Chapter 8: Substrates Surface Quality, Cleaning Adhesion and Adhesion Testing Chapter 9: Surface Treatment of Webs and Foils Chapter 10: Nucleation, Coalescence, and Film Growth 8.1...

Have you ever needed to measure or control tension on multiple strands of web as they are being wound onto individual winders or takeups? A typical example is the case where a wide web of delicate or...

21.1 Drum Surface Roughness The drum surface roughness determines the number of contact points per unit area. The greater the number of contact points, the greater the heat transfer. Typically, a 1...

Chapter List Chapter 19: Machine Specification and Build Issues Risk Analysis Process Chapter 20: Heat Load on the Webs/Foils Chapter 21: Process Variables Chapter 22: Mechanical Design Chapter...