Scan&Sort: Removal of colour contamination from granulate

Optical defects, such as so-called “black specks”, cannot be entirely avoided in the production of plastic granulate, but yet they can cause considerable loss of value. Even slightly contaminated granules that arise, e.g. through hung-up material released from nozzles, oxidation, wear from extruders, etc., often cause fatal production defects in, e.g. the production of transparent film, optical storage media and other high value applications.

Scan&Sort GmbH from Wedel near Hamburg produces equipment for optical sorting that is able to sort out even very slight contamination as small as 0.1 x 0.1 mm and with 99,998 percent effectiveness, increasing the value of the material to a significant degree.

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The material stream to be sorted is firstly divided on a conveyor belt so that a single layer is obtained. The material divided this way is ejected at the end of the belt, taking on a parable-shaped flight path and, immediately afterwards, passes special high resolution cameras. These detect even minimal colour deviation with a resolution of 16m colours, as well as contamination in transparent material up to a size of 100 µm.

The defective particles detected in this way are deliberately blown out of the material stream by a total of 256 high performance jets. The reaction time of the jets amounts here to less than one millisecond, whereby a total number of 4,000 shots per second can be achieved. The throughput of the equipment amounts, depending on the machinery specification, material and the degree of contamination, to as high as 2,500 kg/h.

The equipment is suitable for, e.g. removal of contamination that occurs from change of colours in silos, through accidental damage, to other types of mixing together of different colours.

Another application area is product monitoring during the production process. Here, a part of the stream is passed via a detection unit and this way its quality monitored online. The data obtained is evaluated and passed via SPS to an overall control system. This enables permanent retention of samples taken from the material stream to be eliminated.

The equipment is used primarily in the plastics producing industry. But it also offers smaller and medium sized plastics processors, as well as recycling companies, the possibility of compounding and revaluing goods that have been bought cheaply and to do this in a gentle and efficient manner.

Scan&Sort GmbH belong to CommoDaS-Holding, a company that has developed applications for practical use in the area of optoelectronic recognition and separation for many years at its location in Wedel. Together with the other companies in the group, both CommoDaS GmbH as well as SSE GmbH have produced and put into operation at final customers a large amount of equipment in the last few years for the widest possible types of application.

Scan&Sort GmbH, Wedel

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