1. Application of heat shrink tube in automotive wiring harness
effect
Insulation protection: To prevent short circuit of wiring harnesses, especially in high voltage systems (such as new energy vehicle batteries, motor wiring harnesses) is crucial.
Mechanical protection: wear resistance, tear resistance, to avoid wire harness damage due to vibration or friction.
Sealed and moisture-proof: The joint is sealed by heat shrink to prevent water vapor and corrosive liquid from invading (such as door harness and chassis harness).
Identification management: Color or print heat shrink tubes facilitate the identification of wire harness partitions.
Typical application
High voltage wiring harness: battery pack, charging interface and other parts, need to use high temperature (above 125℃), flame retardant (UL94 V0) heat shrink tube.
Sensor harness: such as oxygen sensor, ABS harness, oil resistance, chemical resistance.
Contact protection: insulation reinforcement of wire harness branches or welding points.
Key points of selection
Material: Common PE (polyethylene), PVC (polyvinyl chloride), cross-linked polyolefin (XLPE) in high pressure environment.
The contraction ratio (e.g. 3:1, 4:1) must match the harness diameter.
Temperature class: the engine room needs to withstand high temperature (-40℃~150℃), and the passenger cabin can be slightly lower.
2. Application of bellows in automotive wiring harness
effect
Physical protection: anti-pressure, anti-impact, protect the wire harness from gravel, metal scratches (such as chassis, near the hub).
Flexible wiring: The corrugated structure facilitates flexible installation in complex Spaces (such as instrument tables, seat harnesses).
Heat dissipation diversion: Open bellows can promote wire harness heat dissipation.
Typical application
Chassis harness: wear-resistant nylon bellows are required for exposed parts.
Engine room: PA6 (nylon) or PP (polypropylene) material is selected for high temperature area.
Door harness: need flexible bellows to adapt to frequent opening and closing.
Key points of selection
Material:
PA nylon: high strength, high temperature resistance (-40℃~140℃), suitable for engine compartment.
PP Polypropylene: Chemical corrosion resistance, low cost.
PE polyethylene: good flexibility, suitable for low temperature environment.
Structure: split mouth type (convenient for later maintenance) and closed mouth type (higher protection).
Flame retardant: Engine bay wiring harness to ISO 6722 or LV 112-3 standards.
3. Cooperative use of heat shrink tube and bellows
Composite protection: in extreme environments (such as high-voltage wiring harnesses of new energy vehicles), first set bellows to provide mechanical protection, and then seal both ends with heat shrink tubes.
Cost balance: the bellows can be used separately in non-critical areas, and the heat shrink tubes can be superimposed on key nodes.
4. Industry standards and trends
Standards: To comply with ISO 19642 (road vehicle harness), SAE J1654 (high voltage cable), etc.
Lightweight: thin wall bellows, low density heat shrink tubes reduce weight.
Environmentally friendly materials: halogen-free heat shrink pipe (such as EU RoHS requirements).