In the complex electrical systems of modern automobiles, wiring harnesses act like "neural networks," running throughout the vehicle and connecting various electronic control units, sensors, and actuators. As a key component for fixing, guiding, and protecting wiring harnesses, the performance of plastic cable racks directly affects the reliability and safety of the entire vehicle. Especially in areas prone to rain, condensation, and car wash moisture, such as the engine compartment, chassis, and doors, cable racks must maintain structural integrity and functional stability under prolonged humid or even high humidity and temperature conditions.
1. Excellent Moisture Resistance and Low Water Absorption
The core material of plastic cable racks is typically engineering plastics such as PA6, PA66, PBT, or PP. These materials have extremely low water absorption rates—for example, PA66 has a water absorption rate of approximately 2.5% in a saturated state, while PBT can be as low as 0.1%. Low water absorption means that the material will hardly swell, soften, or deform due to moisture penetration in humid environments, thus ensuring that the dimensional stability and mechanical strength of the cable rack are not affected. Even under conditions of continuous high humidity or alternating temperature changes, it maintains a firm grip and precise positioning of the cable harness.
2. Superior Chemical Resistance and Mold Resistance
Automotive environments not only contain water but may also involve contact with chemicals such as antifreeze, brake fluid, washer fluid, and de-icing salt. High-quality cable racks use engineering plastics optimized for chemical resistance, resisting the corrosive effects of common automotive fluids and preventing material embrittlement or cracking. Furthermore, in high-temperature and high-humidity environments, ordinary plastics are prone to mold growth, leading to surface powdering or a decline in mechanical properties. Automotive-grade plastics typically contain added mold inhibitors or use intrinsically anti-mold formulations, passing anti-mold tests such as ISO 846, ensuring no biodegradation even with long-term use in tropical or coastal areas.
3. High Mechanical Strength and Creep Resistance
Humid environments are often accompanied by temperature fluctuations. If the material has poor creep resistance, it will slowly deform under continuous stress, leading to loose clips and bracket breakage. PA66 with 30% glass fiber reinforcement is a common choice for cable racks. Its tensile strength can reach over 180 MPa, and its heat distortion temperature exceeds 250℃. Even after aging at 85℃/85%RH for 1000 hours, it still retains over 90% of its mechanical properties. This high rigidity and creep resistance ensure that the cable rack firmly secures the wiring harness under the combined effects of vibration, impact, and humidity, preventing friction wear or connector loosening.
4. Flame Retardancy and Electrical Insulation Safety
Automotive wiring harnesses carry current, and a short circuit can potentially cause a fire. Therefore, cable racks must possess excellent flame retardancy. Mainstream products meet UL94 V-0 or V-2 flame retardant ratings, are self-extinguishing in the presence of fire, and do not support combustion. Simultaneously, engineering plastics themselves are excellent electrical insulators, with a volume resistivity exceeding 10¹⁴ Ω·cm. Even with a water film on the surface, they can effectively isolate the wires, preventing leakage or short circuits and ensuring electrical safety in humid environments.
5. Precision Structural Design and Sealing Fit
Besides materials, structural design is also crucial. Cable racks typically employ closed cable channels, clips with sealing lips, or mounting holes that mate with rubber sealing rings to effectively prevent moisture from seeping into the bracket along the cable harness. Some high-end models even integrate waterproof plugs at the cable harness perforations, creating multiple layers of protection. Furthermore, chamfered edges and the absence of sharp corners prevent scratches on the cable insulation, reducing the risk of electrical failures due to damage at the source.
Although small, automotive plastic cable racks are "invisible guardians" ensuring the stable operation of the entire vehicle's electrical system in harsh environments. Thanks to their low-absorption engineering plastics, chemical-resistant and mildew-resistant formula, high-strength creep-resistant structure, flame-retardant insulation properties, and precise waterproof design, they successfully overcome the multiple challenges posed by humid environments. With the rise of electrification and intelligentization, automotive wiring harnesses are becoming increasingly complex, placing even higher demands on cable racks.
