At K 2013 Sumitomo Demag is demonstrating a new peripheral module called activeColourChange. With the product, the group has developed a pigment dosing system which allows extremely short colour change times to be performed when using liquid colours.
The colour is fed directly from a closed system into the metering zone of the melt-filled injection unit. In contrast to colouring with masterbatch, the upstream zones (the feed and compression zones) are kept free of colour, which in theory means that less cleaning is required.
The group is demonstrating activeColourChange on its new Systec SP 280 (producing one litre buckets) with three different colours at K this week. The colour dosing and change system can process with up to five colours. It is integrated into the NC5 plus machine control and is activated and deactivated automatically.
During the colour change process the first liquid colourant is automatically deactivated once the selected product volume is reached. When changing the colour, the screw channel and the front of the screw can be cleaned before the activation of the second colour.
The colour is fed using 'ViscoTainers' - plastic containers with an integrated dosing function, as well as a control and drive unit. To keep equipment clean, all parts of ViscoTainer that come into contact with the liquid are isolated from the rest of the peripheral components.
activeColourChange uses feed pumps which allow reproducible metering of smaller colour doses under high melt counter-pressure. For high homogenization, the metering zone of the screw is equipped with a mixing section.