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Silane-crosslinked polyethylene  (XLPE) cable compounds are a type of thermoset insulation used in electrical cables. They are produced by chemically crosslinking polyethylene molecules using silane compounds, which transform the linear molecular structure of polyethylene into a three-dimensional network. This process enhances the material’s thermal stability, mechanical strength, and electrical properties, making it suitable for various applications, from low to high-voltage power transmission to automotive systems.

Processing challenges and solutions for silane crosslinked XLPE cable compound materials

The manufacturing of silane-crosslinked polyethylene (XLPE) cable compound materials faces critical technical challenges, including pre-crosslinking control, thermal shrinkage optimization, crystallinity adjustment, and process stability. Recent advancements in material science and production methodologies are addressing these hurdles, significantly improving product quality and processing yields.

1. Pre-Crosslinking and Scorching Mitigation

 Challenge: In the Sioplas process, moisture exposure during blending and extrusion of Parts A and B can trigger premature hydrolysis and condensation reactions. This leads to uncontrolled pre-crosslinking, resulting in higher melt viscosity, poor flowability, rough surfaces, and compromised insulation properties like lower breakdown voltage.

Solution：

Lubricant Additive Integration: Incorporating silicone-based masterbatches, such as SILIKE’s silicone-based processing additive LYPA-208C, effectively improves melt flow, reduces melt adhesion to screws and dies, and effectively prevents pre-crosslinking without affecting the final crosslinking quality.

Silicone additive LYPA-208C has strong anti-pre-crosslinking performance without affecting final crosslinking quality.

Silicone masterbatch LYPA-208C eliminates surface defects like “shark skin” and enhances surface smoothness

Silicone-based additive LYPA-208C significantly reduces extrusion torque and prevents motor overload

Siloxane Additives LYPA-208C boosts extrusion line stability and output rate

Temperature Gradient Optimization: Implementing segmented extrusion barrel temperatures between 140°C and 180°C helps minimize localized overheating. Reducing residence time in high-temperature zones further decreases the risk of premature crosslinking

Two-Step Processing: Employing a two-step method, where silane is grafted onto polyethylene prior to extrusion, alleviates the pressures associated with in-line grafting, thereby reducing the likelihood of pre-crosslinking during extrusion compared to single-step approaches.

2. Thermal Shrinkage Performance Optimization

Challenge: Excessive insulation layer shrinkage risks structural deformation and electrical failures, linked to crystalline orientation and cooling dynamics.

Solutions:

Multi-Stage Cooling Systems: Utilizing a sequence of hot, warm, and cold water cooling stages slows crystallization rates, effectively managing thermal gradients and reducing shrinkage.

Extrusion Parameter Adjustment: Using high length-to-diameter ratio extruders (≥30:1) extends melt retention time, suppressing unwanted crystallization. Employing compression dies for smaller cables (≤6mm²) minimizes orientation-induced crystallization, further controlling shrinkage.

Material Selection: Adopting two-step silane-crosslinked polyethylene allows for finer control over crystallization behavior, contributing to improved thermal stability.

3. Balancing Crystallinity and Mechanical Properties

Challenge: High crystallinity causes brittleness, while insufficient crystallization undermines thermal resistance.

Solutions:

Melt Temperature Control: Elevating melt temperatures to 190°C–210°C with extended dwell times reduces crystal nucleation, though careful management is necessary to prevent premature crosslinking.

Catalyst Masterbatch Design: Utilizing twin-screw extrusion ensures uniform dispersion of organotin catalysts, optimizing the interplay between crosslinking and crystallinity to enhance mechanical properties.

4. Enhancing Process Stability

Challenge: Sensitivity to process fluctuations triggers extrusion pressure instability and surface defects.

Solutions:

Equipment Upgrades: Implementing dual-cone drum mixing systems ensures homogeneous dispersion of silane additives, with mixing durations exceeding 2.5 hours to achieve optimal consistency.

Real-Time Monitoring: Continuous monitoring of screw current and rotation speed allows for prompt adjustments to temperature settings and mold cleaning protocols, maintaining stable processing conditions.

Industry Trends and Future Outlook of XLPE cable manufacturing

The integration of two-step processing combined with functional additives, such as silicone-based masterbatches, has emerged as a leading strategy to overcome processing challenges in XLPE cable manufacturing. These innovations have reportedly increased production yields by over 10~20% in pilot applications, enhancing the reliability of XLPE cables in power transmission and automotive sectors. Looking ahead, manufacturers are focusing on research and development of adaptive cooling technologies and intelligent process controls to further refine XLPE material performance, meeting the growing demand for high-performance cables

By embracing these advanced processing strategies and material innovations, manufacturers can significantly enhance the efficiency and quality of XLPE cable production, ensuring the delivery of superior products that meet the evolving demands of modern electrical applications.

For the method to optimize XLPE cable processing and surface performance, contact SILIKE Tel: +86-28-83625089 or via email: amy.wang@silike.cn, or visit the website  www.siliketech.com to learn more. Chengdu SILIKE Technology Co., Ltd – A pioneering Chinese silicone additive specialist with many years of expertise in  wire and cable compounds.

Unlock higher productivity and cable performance—choose SILIKE Silicone Processing Aids for your XLPE Cables compounds solutions.
Whether you’re aiming to optimize production efficiency, prevent pre-crosslinking in XLPE, eliminate surface defects like “shark skin” , enhance surface aesthetics, or reduce downtime, SILIKE Silicone Masterbatches provide the performance edge your XLPE cable line needs.