Ensured concentricity

The highest quality, process optimization and cost reduction are decisive factors by which manufacturers of wires and cables as well as hoses and tubes will be evaluated in the global competition – today and in the future. These claims require innovative measuring technology. An important parameter during the extrusion of products is the compliance with specifications such as concentricity of the conductor within the insulation respectively the consistent wall thickness distribution of hoses and tubes. With diverse systems for a precise measurement of the eccentricity, SIKORA creates preconditions for an optimal production.

If a conductor is not exactly centrically within the cable cross section, a reduction of the overall wall thickness to the nominal value namely effects a reduction of material consumption. Nevertheless, single wall thicknesses at different measuring points show strong variations to the nominal value so that, in parts, a too thick or even a too thin insulation is applied to the cable causing unforeseeable consequences regarding quality and safety of the end product.  

Eccentricity measurement of a conductor within insulation

The CENTERVIEW 8000 is based on an optical and inductive measuring method. The inductive measuring circuit, arranged between two optical measuring planes, determines the exact conductor position. The optical system measures the outer wire position. An eccentricity measuring value results if both positions differ from each other. Simultaneously, the optical system precisely detects the diameter and ovality. All required calculations and analyses happen within the measuring system. Measuring results are available via several interfaces for transfer to a display and control system or to a plant computer.

Eccentricity measurement of a conductor within insulation

X-RAY 6120 PRO eccentricity measurement during cable extrusion

SIKORA’s X-ray measuring systems X-RAY 6000 PRO for the use in extrusion lines which manufacture data, automotive and installation cables as well as hoses and tubes reliably detect the eccentricity of products.

Technical basis of the X-RAY 6000 PRO is an imaging method. Two X-ray tubes at right angles to each other illuminate the product crosswise to its axis. Opposite these two X-ray tubes, a line sensor each is positioned. The line sensors are coated with a scintillator, which converts received X-ray radiation into light. Within milliseconds an image of the product is created. Therefore, during the ongoing production precise values are continuously recorded. The evaluation is made directly from the X-ray image. Recording of material with different attenuations, a special analysis and mathematical algorithms result in a visible contrast of the different layers as well as a precise measurement of product dimensions down to micron accuracy. The X-ray technology does not need an adaptation of materials, works without any coupling media, which is required e.g. for ultrasound technique. Furthermore, the technology is independent of the temperature of the extruded material.

X-RAY 8000 NXT eccentricity measurement for high-voltage cables

During the production of medium, high and extra-high voltage cables in CV lines, the eccentricity measurement is done by the X-ray measuring device X-RAY 8000 ADVANCED/NXT. The product is contactless scanned with X-rays by two high-speed-scanners. The measured cable values, including eccentricity, are calculated directly out of the X-ray image. Radiation absorption changes at the layer transitions. The transition points between the different insulation layers are clearly identifiable and the eccentricity is precisely determined.