Tension control system registers label success

Edited by the Engineeringtalk editorial team Nov 27, 2003

Custom label manufacturer Skanem has recently started retrofitting ZF hysteresis units to its Gallus printing machines to match changing industry demands.

Custom label manufacturer Skanem has recently started retrofitting ZF hysteresis units to its Gallus printing machines to match changing industry demands.

The precise tension control provided by the ZF system allows multiple layers of material to be passed through seven printing and cutting operations at a speed of 50m/min, with a standard of repeat accuracy high enough to eliminate wastage.

"We fitted the first ZF hysteresis brake and clutch system 12 months ago after consultations with Bedfordshire based systems specialist, DJ Automation", explains Peter Coutts, Maintenance Engineer at Skanem Cardiff.

"A customer had asked for a special peal-and-seal type label which required us to feed an extra layer (web) of film into one of our Gallus machines.

When you take into account that the Gallus is capable of producing over 3000 colour labels a minute from a 2km roll, precise tension control becomes a priority in the retrofit design".

"Following the success of the first conversion we have installed the ZF system on three different types of presses all offering both ease of set up and integration", continues Coutts.

"We traditionally used a friction based control system, but this did not have the accuracy and flexibility needed for the complex upgrades".

Depending on the type of label being produced, the Gallus machine will perform between four and seven different operations, including the application of seven colours, hotfoil and rotary cutting processes.

Making sure that webs are fed into the machine with an even tension can make the difference between a highly efficient set up and large amounts of wasted time and materials.

David Levett, Sales Manager at DJ Automation explained that: "The rolls of film are 20cm wide and fed through the machine at a rate of 50m/min.

This required us to specify an EBU brake on the "off" wind and an EKU series clutch for the "on" wind operations with both controlled by a ZF ERM unit.

The beauty of the system is that, once it has been programmed, it acts as a standalone unit, facilitating set up and minimising maintenance".

"We also supplied a customised motor gearbox for the rewind", he continues, "and installed Honnigman sensors in the roller end shafts, allowing the ERM unit to precisely monitor speed and adjust tension accordingly.

The system is one we recommend for a broad range of tension control applications from manufacturing computer cables to medical dressings, and due to its non-contact operation, has proven itself in a multitude of other clean-room applications".

The noncontact operation of ZF's hysteresis brakes allows for an extremely long service life and avoids the creation of dust particulates, making them ideal for test rigs and production environments where levels of air-born contamination have to be minimised.

The ZF range of brakes includes a high power series that offers (continuous) slip powers from 250 to 2000W and peak capabilities of twice these figures.

ZF's range of hysteresis clutches are especially useful for winding-on applications in paper or food packaging industries and the four different versions available cover most requirements with torque capacities ranging from 0.08 to 520Nm.