Infeed Web Tension Control. Full control

Adjustment and control of the web tension is necessary to obtain good colour printing, prevent breaks and to enable the automatic registry control systems to operate correctly.

Machines that were built 20 to 25 years ago for printing in monochrome are still often used today to print in colour. Normally, the web tension can only be adjusted from the reel brake on the reel stand, or in some cases at the input to the folding machine, which is not enough to obtain the precision required for good colour printing.

More modern machines started to include web tension controls to alter the web tension indirectly by adjusting the speed of the take-up roller via various mechanisms, although the response was relatively slow.

Furthermore, even in the most sophisticated printing presses, paper breaks are considered to be normal, especially when printing in colour. It is inevitable that several copies are lost during the adjustment stage at the start, a situation which worsens dramatically when printing in colour with presses that were not designed for this, and where saturation problems are also often encountered.

Description

Ensuring correct and stable values for the web tension in each section is an essential condition for obtaining high production yields, constant high quality and reduced waste.

The FULLCONTROL system described here is the most complete and accurate system on the market. It achieves total control of tension by acting on three levels:

• Tension adjustment (Infeed).
• Tension control throughout the web.
• Simultaneous tension control on a set of webs.

In addition, the FULLCONTROL system has been designed so that all adjustments are made in accordance with the physical properties of the paper currently in use. Therefore, it is the only system which allows different types of paper to be printed at the same time and ensures that values for resistance to breakage are not exceeded.

Advantages

• Ensures high performance of the automatic colour saturation control systems.
• The compact design means it can be used with any type of printing press. There are models for single and double widths.
• Enables the tension to be adjusted and controlled at various points on the web selected by the printing press, in accordance with the print requirements.
• Low energy consumption. Designed so that, in normal operating mode and when braking the web, it acts as a generator and returns energy to the grid.

Benefits

• 80% less paper waste due to reduced breaking.
• Ensures that the machine operates correctly, even with low quality paper.
• Reduces paper waste by over 90% from poor colour saturation due to variation in the web tension during production.