Tension control in narrow web labelling machines

Andantex has launched a new range of EMP brakes equipped with the most comprehensive range of cooling systems - necessary components to achieve higher linear speed.

Resolving web handling problems (slack web, product stretching, loss of registration, product breakage etc) by improving tension control is a cost-effective way to refurbish existing equipment or to enhance the performance of new equipment.

It allows an increase in linear speed, production quality and flexibility, and reduces waste.

To do this, Andantex, with Merobel, have launched a new range of EMP brakes equipped with the most comprehensive range of cooling systems - necessary components to achieve higher linear speed - and a new digital tension controller, the DGT 300.

How can people be so confident that EMP technology is still the best solution for applying variable torque in tension control?.

The reason is that EMP brakes and clutches are more reliable (wearless) and easy to implement (constant torque) than friction systems and more cost-effective and easy to maintain than shaftless systems.

Andantex claims this new range is the most reliable and widest on the market.

The global reliability of the Merobel EMP brake and clutch comes from a combination of many different design improvements introduced in the last decades.

These improvements include factors such as specifically developed wearless surface treatments, magnetic properties of the chosen steel quality, powder composition, ball bearing optimisation to resist to high temperatures, sealing quality and thermal resistance.

As an example, the company's knowhow of thermal capabilities has been dramatically improved by the computerised thermal models of the brakes given by specialised CAD software.

Because of the new opportunity that allows simulation of the exact working conditions on computers, the technical office is now in a better position to finely define the temperature level in any crucial part of the brake.

The best solution in terms of cooling system (cooling fins, axial fan, radial fan, or water jacket cooling system) can then be chosen from known machine working conditions.

The new EMP brake and clutch range is the widest on the market.

As the versatility of narrow web label machinery has become more important, so the available global range of torque, from 2 to 1000Nm has also become more crucial when considering the application needs.

First, the web diameter ratio between full and empty is usually about 1:10 and the width ratio can be 1:4.

Secondly, the material range which can be processed on the same machine, leads to a wide product tension variation.

For example, looking for printing from 12um bop to 600um cardboard on the same press means a typical material tension variation from 1:20.

The capability for the EMP brake and clutch technology to offer the widest available continuous torque range is one of its key features.

This capability relies on constant research and development for solutions to decrease the drag torque, as well as for the internal magnetic field optimisation to allow a better linearisation of the characteristic curve.

This range is offered with the widest choice of cooling systems: cooling fins, axial fan, radial fan, or water jacket cooling system.

The most innovative system is, without doubt, the axial fan: more compact, this system is easy to fit, increasing the heat dissipation power from 125 to 2000W.

The new EMP brake and clutch range is environmentally friendly.

Of course it is dustless by design, as the magnetic powder is sealed inside the unit.

For food and pharmaceutical processing and packaging, this technology is particularly suited and widely used, as well as adhering to the ISO14000 regulation needs.

The sealing quality is now considered as a 100% reliability target, and specific improvements were recently applied on this specific design key point.

Particular attention was also paid to customers need for quiet operation.

Specific surface treatment characteristics, as well as exact powder composition helps to improve the natural noiseless trend of the EMP technology.

Even using the world's best brake, a tension control system must also include controllers and sensors in order to reach its goal: a guarantee of different, accurate and consistent tension levels on any of the product that the application may require (up to 1% precision).

The DGT300 offers all the special features required to deal with the application parameter variations: web elasticity, bobbin rotational inertia, continuous or stop and go running processes, range of diameter variations, and many more.

These are the main issues that demand different sets of regulation parameters in order to keep the system stable at any time.

This latest generation of Merobel's digital controllers from Andantex has been developed with all these needs in mind.

Designed for both closed loop and open loop tension control, the DGT family of controllers is the up-to-date turnkey solution for unwinding, rewinding and intermediate tension control applications.

Allowing 100% setting up through its user friendly Windows PC interface, or through its front panel keyboard, these devices include all the requested web tension control specific functions: E-stop proportional to the set point, soft start, hold and release, taper tension and no-stop splice turrets.

Advanced regulation features are also offered, such as automatic PID coefficients variation, open loop plus closed loop control mixed together, inertia compensation, Smooth starting up with programmable slope as well as motors and drives specific algorithm.

Compatible with any usual position sensors, ultrasonic sensors, and any kind of load cells technology, the design of this product family gives the benefit of fully digital calibration procedures.

In addition, direct control of EMP brakes and clutches is available through the built-in power amplifier and motor drive control can be made with a standard analogue output.

This system offers the advantage of easy tuning through a simple Windows PC interface and has better flexibility to change production batches.

For maintenance teams, wherever they are in the world, this is, of course, an important issue as it is crucial to be able to read and modify all the parameters, and to make data records of the I/Os for easier troubleshooting.

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