Key takeaways
The first digit of an IP rating covers dust (6 = dust-tight) and the second covers water (5 = water jets, 7 = short-term immersion). IP65 and IP67 use completely different water test methods, executed per the corresponding clauses of GB/T 4208. For automotive parts: exterior body-mounted parts usually require IP67 and cabin-mounted parts are mostly IP65, always subject to the customer specification.
Ingress protection is one of the most frequently quoted figures in automotive electronics tenders, yet the test method behind the three characters "IP67" is widely misunderstood. Start with the conclusion: each digit governs one thing, and each level of the second digit corresponds to a completely different water test.
1. What each digit governs
Under GB/T 4208 (identical to IEC 60529), the first digit covers protection against solid foreign objects and dust: IP6X means dust-tight, verified in a dust chamber with a negative pressure applied. The second digit covers protection against water ingress: IPX5 uses a nozzle jet, IPX7 is short-term immersion at a specified depth, and IPX6 is a powerful jet. Higher numbers mean harsher conditions, but there is no such thing as "IP67 automatically covers IP65" — the two are parallel tests, not a hierarchy.
2. The details that decide the test
The jet test turns on nozzle diameter, water pressure, flow rate and duration, with the sample rotated slowly so every face is wetted. The immersion test turns on water depth and immersion time; controlling the temperature difference between the water and the sample helps expose sealing defects. The post-test inspection matters just as much: no water inside the housing, functions normal, insulation performance not degraded — all three must pass.
3. Why automotive parts fail here so often
The usual failure points: insufficient compression or distorted assembly of the seal, a failed breather valve letting the pressure differential draw water in, poor sealing of connectors and cable exits, and screw holes that penetrate the housing. One IP pre-compliance round during development is far cheaper than reworking tooling and structure after mass production starts.
4. How to choose the level
Look at the mounting location: parts exposed outside the vehicle, in wading or car-wash conditions (inside the bumper, on the chassis, near the wheel arch) are usually IP67; parts inside the cabin under the headliner are mostly IP65. The OEM technical agreement decides in the end — some OEMs layer their own splash and condensation conditions on top of the national standard.
Turnaround time is arranged according to the actual project. You are welcome to state your target date when submitting samples; we will check it against the current schedule, confirm a feasible plan with you, and update you at each milestone.
