Typical layout of a Coperion SCP semi-automatic strand pelletising system

water, drying, evaporation in ambient air and pelletising. “The difference is that the water bath is replaced by a combination of a chute, flooded by water, and a belt section that can be sprayed with water as well,” he says. “In the belt section there are suction boxes included for strand drying. The end of the belt is always free of water in order to provide time for evaporation of the remaining water vapour to the ambient air. The belt enters the pelletiser directly.” According to Coperion, the difference between the semi-automatic and the automatic systems is that start-up of the SCP has to be carried out manually by an operator scraping the strands at the die. Following from there, strands are transported automatically by the flow of the water and gravity via the chute to the belt and into the pelletiser. Even if strands break during production, they are transported to the pelletiser automatically with no operator required. The ASC system offers fully automatic start-up.

Right: Water pre-separation locations (top image) and suction ports (lower image) on Coperion’s SCP strand pelletisers can be placed to achieve

optimal de- humidification

Coperion has also added new technical features to its pelletising systems. “Bigger throughputs and a more expensive labour force have increased the demand for automation,” says Wygas. “We have added intelligent communication and interaction with the extruder and other components of the production line. In addition, all components can be adapted depending on the line throughput.”

Automation appeal Automation is intended to eliminate the risk of unforeseen events that could result in blocking of the strands. “The machine recognises large lumps and problems affected by that and can inform the operator or stop the process. There is also continu- ous supervision of process parameters, such as water and strand temperature, ensuring that the correct documentation can be produced. Water temperature control is automatically adapted to process demands, and heating as well as cooling can be realised,” Wygas says. Stable processes, good usability and easy maintenance are also increasingly important, he says, adding that the company offers a cantilevered single bearing design for the transportation belt on the automatic strand pelletising system, which ensures an easy change of the belt within 10 minutes. “We have also added ‘shark fins’ between the water chute and belt, as well as brushes or rollers on the belt, in order to stabilise strand behaviour and ensure a good cutting result,” he says. “In addition, because the length of the water chute and the belt are fixed, it is important for customers to be allowed as much flexibility as possible in order to produce a wide range of recipes. Therefore, water pre-separation can be done in different positions on the water chute. Furthermore, the water flow can be adjusted in order to meet product requirements. The belt can also be flexibly cooled down depending on

46 COMPOUNDING WORLD | January 2019



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