semi conductive cable compounding
Medium-voltage (MV) and high-voltage (HV) cable insulation is enclosed between two concentric semi conducting layers to homogenize the electrical field in the insulation material. These layers generally comprise ethylene-based polymers like EVA, EBA or similar, with a high content of conductive materials such as carbon black, graphite, or carbon nanotubes to effect semiconductivity.
The process requirements for semiconducting cable compounds are very demanding. Conductivity values must be dependable both at room temperatures and at higher operating temperatures. Highly structured carbon black must remain unchanged and be distributed extremely homogeneously to form the required conductive network. The polymers used must be degraded as little as possible. The surfaces of the coextruded layers must be very smooth and uniform. Usually peroxide-based cross-linking is required.
XINDA Co-kneader is ideal for Semi conductive cable compounds processing:
1, the high content of carbon black can be fed into different barrel sections
2, the mild shearing doesn't break the carbon black
3, the white oil (subject to formula) can be injected to barrel by hollow pins
SJW XINDA Type Cascade Three Flights Co-Kneader Compound Extruder for Semi conductive Compounds
The XINDA SJW Three flights compouding system,each spiral is broken by 3 gaps per revolution to locate the kneading flights, 3 rows of kneading pins,which are individually inserted in the barrel per 120 degree. The reciprocating wobble-box synchronizes the shaft rotation and oscillation so that each revolution of the screw is accompanied by one full stroke forward and backwards.This ensures optimal distributive and dispersive mixing with minimal energy consumption.
Advantages of the XINDA Co-kneader
The Co-Kneader, a mild-shear rotating and reciprocating single-screw extruder, is designed for shear and temperature sensitive compounds. The flights on the screw are interrupted and interqct with three rows of stationarv kneadina pins located in the barrel wall. The interaction between the moving flights and the stationary pins provide dispersive and distributive mixing simultaneously. Axially opened split barrel guarantees ease of cleaning. Those splined, segmented screw elements and pins can be changed easily according to different processing techniques. In addition, some pins are hollow inside, thermocouples can be inserted to get the accu- rate temperature of the materials inside the barrels, so as to liquid additives injection. Different from other extruders, the kneading process is achieved radially and axially at the same time. All in all, Co-Kneader has outstanding kneading, mixing efficiency and high degree of self-wiping. It is the most suitable for compounding purposes.
Cascade two-stage co-kneader system for semi conductive Compounding: Co-kneader and discharging extruder build up two stage compounding system.
Advantage of the compounding system:
--Lower energy input, lower melt temperatures
--Extremely homogeneous mixing, no shear spikes, equal treatment of polymer matrix
--High degree of self-wiping and have no dead spot
--Dispersive mixing without destroying delicate fllers
--High volumetric loadings of fllers and additives
--Efficient blending of liquid components
--Broad application for compounding without changing hardware
--Axially opened split barrel guarantees ease of cleaning and fast maintenance
--Replacement parts, such as screws, barrel lining and pins can be changed individually
Semi conductive Compounds:
--For MV cables
--For HV cables
Details Images
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