How to eliminate contamination thanks to the latest material sorting
Plastics used for the insulation of medium, high and extra-high voltage cables must meet the highest standards of purity. The two most common materials are XLPE (cross-linkable polyethylene) and PP (polypropylene). Both materials have their specific advantages, but also special requirements that must be considered in the extrusion process. Sikora's Purity Scanner Advanced is an advanced inspection and sorting system that reliably ensures the material quality of both plastics.
Impurities in XLPE and PP - a common challenge
XLPE is a proven insulation material for medium and high voltage cables, manufactured by chemical cross-linking of polyethylene. It offers good electrical and physical properties, but requires long degassing times and is not recyclable. PP is a modern alternative with similar properties, but does not require cross-linking. This enables a more efficient, continuous production and also makes PP recyclable. However, PP has a higher degree of contamination, especially by metallic particles, which can affect the quality of the cable insulation. Regardless of the material used, the purity of the pellets is a decisive factor for the quality of the final product. Impurities such as metallic particles affect both XLPE and PP for use as insulation.
State-of-the-art inspection and sorting system ensures quality
The Purity Scanner Advanced by Sikora is the ideal inspection and sorting solution for XLPE and PP. It combines X-ray technology with optical camera technology to real-time detect and sort out contaminated pellets such as metallic particles, black specks and yellowing. This ensures that material quality is continuously monitored, so that only pure pellets enter the further processing.
The system detects even the smallest impurities: down to 25 µm for black specks and 50 µm for metal particles. An intelligent sorting process, known as “hybrid blow-out”, minimizes the rejection of valuable, clean material. Depending on the customer's requirements, it is possible to define which contaminants are tolerable. Small, light black specks can be removed with a smaller air-blast unit, thus reducing the by-catch. Critical contaminants, such as metal particles, which can impair the functionality of the end product, are sorted out with a larger unit. This highly precise interplay ensures the highest material quality.
In many production environments, space is a limiting factor. The Purity Scanner Advanced has been specially developed for a compact and efficient integration, so that optical and metallic sorting is done by one device. This reduces costs and ensures a smooth material flow.
In order to avoid secondary contamination during the inspection, Sikora relies on an enclosed material transport via stainless steel channels that does not introduce any particles into the material flow. The targeted sorting is carried out by means of purified compressed air, which ensures the purity of the XLPE or PP pellets.
For over 10 years, medium, high and extra-high voltage cable manufacturers worldwide have relied on the Purity Scanner Advanced - now in its fourth generation. Regardless of whether XLPE or PP is used, the purity of the insulation material remains a critical factor in cable quality. Thanks to state-of-the-art inspection and sorting, the Purity Scanner Advanced helps to optimize production processes, reduce costs and promote sustainability in the plastics industry.
