Running Registered Materials on the Doyen Four Side Seal Machine Maurice Smith - Customer Care Manager, Doyen Group PLC The Doyen Four Side Seal Registration System works by monitoring every registration mark by momentarily increasing or decreasing the speed of the side seal units to keep the pack in register. As such, when registration is switched on, the machine speed is continually adjusted to suit the registration marks that are printed on the material.

With this system of automatic compensation, it is important that the printed positions of the registration marks are maintained within specified tolerance. If the registration marks are not within specification (and in particular if they vary in pitch) the finished pack can be adversely affected in respect of cut-off length, cross seal position and registration of the print to the pack and knife position. The pack quality will also be affected in the same way if the drive system carrying the web through the machine is slipping. If you are experiencing problems of variation in cut off length or pack length described above, then we advise the following:-

1. Switch the registration system off and run the machine. Note the size of the pack that is being produced in comparison to the target and also observe the drift that is being experienced on the registration mark. If the pack length being produced is the correct size, all packs are a consistent length, and there is minimal drift on the registration mark, then it is most likely that variations in the registration mark are causing the pack quality problems.

2. Always increase the target length on the touch screen by approximately 0.5% of the desired pack length - i.e. normally some 0.5mm to 2mm longer than the desired length. With the longer target length programmed, the machine will then always slow to adjust for the registration mark rather than accelerating. Slowing down to adjust is a more stable process and will give improved cut off accuracy, especially if some slipping is also being experienced. Please note it is only possible to set the touch screen in this manner on machines that are fitted with, or have been upgraded to, Allen Bradley control systems with colour touch screens.

3. If, when you switch the registration mark off, the packs produced are significantly shorter than the desired length, then either the rubber drive wheels are grossly undersized, or you are experiencing slipping, or the target pack length (on the touch screen) has been set too short.

4. Regularly maintain and replace the side seal rubber drive wheels and the auxiliary drive rollers. Doyen are now offering an exchange recovering service for these components at a competitive price.

5. Check the registration accuracy on the material by measuring a series of marks. In the worst case, depending upon how many packs are between the registration scanner and the cross seal and cut off station, and the nature of the variation of the registration, the error observed on pack length could be up to twice the amount that is measured as registration error. Poor quality registration will produce poor quality packs.

6. Remember that wear on the rubber rollers will reduce the length of pack being fed. If you are in doubt as to whether or not you have set the machine correctly, try turning the registration off and observing the length of pack that is produced. The length of pack that is produced without registration under these conditions should be the same or slightly longer than the desired length of pack.