Analysis Of Causes And Solutions For Busbar Slippage And Misalignment in Heat-Shrink Tubing Under High-Temperature Cycling Conditions

As new energy vehicles, energy storage systems, and high-voltage electrical equipment evolve toward higher power densities, busbar connection systems are frequently subjected to environments characterized by high currents, thermal cycling, and mechanical vibration. While heat-shrink tubing serves as a critical insulation and protection component for bars-enhancing electrical safety and mitigating short-circuit risks-issues such as slippage, axial displacement, or edge lifting can occur during prolonged thermal cycling. Displacement of Heat Shrink Tube Copper Busbar Connection under high-temperature cycling conditions is typically linked to material properties, surface treatment, installation techniques, and structural fixation methods; addressing these issues requires systematic analysis and the implementation of improvement measures.

The repeated sliding and misalignment of heat-shrink tubing under high-temperature cycling conditions primarily stem from the combined effects of multiple stresses. Improper material selection or substandard installation practices further exacerbate these sliding failures. The specific causes can be categorized as follows:

• Accumulation of cyclic thermal stress: During equipment operation, busbars undergo continuous temperature cycles-heating up when energized and cooling down when de-energized. Long-term, repeated thermal expansion and contraction exert persistent tensile stress on the heat-shrink tubing. If the tubing material has a low elastic modulus and insufficient creep resistance, it will gradually loosen and shift, leading to progressive sliding issues.
• Insufficient interfacial friction/adhesion: Residual oil or dust on the busbar surface, or a substrate surface that is too smooth (lacking effective roughness), significantly reduces the interfacial adhesion of the heat-shrink tubing after shrinking. Because the tubing cannot fit tightly against the busbar substrate, it is highly susceptible to loosening and misalignment under conditions of fluctuating temperatures and slight vibrations.
• Defects in the heating installation process: Uneven heating, localized overheating, or incorrect heating sequences during the shrinking process lead to an imbalance in the internal stress distribution of the tubing. Upon cooling, issues such as stress rebound and localized lifting occur, gradually causing the tubing to shift overall and ultimately resulting in persistent sliding and misalignmen failures.

To thoroughly resolve sleeve slippage and ensure long-term, stable adhesion, the application of customized heat-shrink tubing for copper busbars must strictly follow a standardized, multi-step process involving substrate pretreatment, precise selection, controlled heating, and mechanical securing. The specific operational steps are as follows:

• Substrate Cleaning and Pretreatment: Thoroughly remove oil, dust, and other impurities from the busbar surface using anhydrous alcohol. Sand down oxidized areas to restore a smooth metal surface, allow it to dry completely, and eliminate any contaminants that could compromise sleeve adhesion.
• Precise Selection of Specialized Tubing: Prioritize the use of irradiation-crosslinked heat-shrink tubing featuring a shrink ratio of at least 3:1, a long-term temperature rating above 135°C, and axial shrinkage variation controlled within ±5%. The use of standard, low-temperature-resistant PVC tubing is strictly prohibited to avoid material-related issues such as thermal expansion/contraction and loosening due to aging.
• Standardized, Uniform Heating: Apply heat using a heat gun, strictly maintaining the temperature between 120°C and 140°C. Heat the tubing evenly from the center outward toward both ends; avoid localized overheating to prevent internal stress rebound and uneven shrinkage.
• Mechanical Reinforcement and Positioning: After the heat-shrink process, install limiting structures-such as insulating clips or specialized mounting brackets-at key points at both ends of the tubing. These physical restraints counteract axial displacement forces caused by thermal cycling, thereby fundamentally preventing the sleeve from slipping or shifting out of position.

To effectively prevent slippage over the long term, strict standards must be established for material selection and acceptance; Heat Shrink Tube Copper Busbar Connection must be selected to provide a safety margin relative to the equipment's maximum temperature rise. Recommended specifications include a temperature rating of -55°C to 135°C (or higher), with an upper temperature limit at least 20°C above the busbar's peak operating temperature. The heat-shrink ratio should be no less than 3:1, and axial shrinkage must be controlled within ±5%. The material requires a tensile strength of ≥8.0 MPa and minimal degradation of mechanical properties following long-term thermal aging. Final acceptance criteria require the tubing to fit tightly without air bubbles, wrinkles, or edge lifting; the installation is deemed合格 (compliant) if it shows no significant displacement when subjected to manual pulling.

Battery busbar specifications vary according to voltage and power ratings; please feel free to contact us for professional technical guidance if you require a customized heat-shrink tubing solution for copper busbar connections tailored to high-temperature cycling conditions.