Extrusion International 2-2025

34 Extrusion International 2/2025 MEASUREMENT TECHNOLOGY, QUALITY CONTROL 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 speci c 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 ef cient, continuous produc - tion and also makes PP recyclable. However, PP has a higher degree of contamination, especially by metal- lic 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 nal product. Impurities such as metallic particles af - fect 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 tech- nology to real-time detect and sort out contaminated pellets such as metallic particles, black specks and yel- lowing. This ensures that material quality is continu- ously 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 mate- rial. Depending on the customer's requirements, it is possible to de ne which contaminants are tolerable. Small, light black specks can be removed with a smaller air-blast unit, thus reducing the by-catch. Critical con- taminants, 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. Impurities such as metallic particles can affect both XLPE and PP. The PURITY SCANNER ADVANCED detects the smallest contamination in the material – before they enter the extrusion process The PURITY SCANNER ADVANCED for the inspection and sorting of XLPE and PP pellets