One-sentence answer: Control boxes and PDU housings integrate busbars, relays and fuses inside; a housing sealing failure allows moisture ingress and causes creepage, short circuits and contact oxidation. Using the CTS Sentinel C28WE (C28) leak detector to perform pressure decay or vacuum decay leak testing on the housing cavity as a whole is a general air tightness test solution for new energy control box production lines.
Housings are mostly die-cast aluminum; porosity may only be exposed after machining, invisible to the naked eye yet sufficient to form a persistent micro-leak, with scattered leak locations and poor regularity.
Cable glands, high- and low-voltage connectors, breather valves and pressure relief holes are concentrated on the same panel, each requiring individual plugging; fixture complexity directly determines the false-reject rate.
Once the housing is sealed and the cover installed, disassembly destroys the adhesive layer, making rework labor and material costs both high, and a re-test is mandatory.
Sealing locations: upper and lower parting surfaces (sealant or seal strip), connector panel gaskets, cable glands and harness outlets, explosion-proof breather valves, sealant curing surfaces.Consequences of leakage: moisture and wash water enter the housing, the creepage distance of busbars is compromised causing insulation failure; contact oxidation raises contact resistance; long-term corrosion may cause sudden power loss during vehicle service, which is a safety-related failure.
It depends on the process agreement. Where internal pressurization is allowed and contamination-free testing is pursued, use pressure decay; where components are already assembled or the external moisture ingress direction needs to be simulated, use vacuum decay. The C28WE can switch between the two methods on the same instrument by program, with no need to equip one machine for each process.
Rely on resolution and consistency, not on the absolute value of a single reading. A leak rate resolution of 0.0005 scc/min (a resolution specification, not equal to the minimum leak rate the instrument can detect) combined with automatic calibration using the built-in calibrated leak can reliably judge persistent micro-leaks caused by porosity; at the same time, it is recommended to move die-cast part testing forward to after machining and before assembly.
It is recommended to separate them. Whole-housing testing is the assembly-level gatekeeper; connectors and cable glands can be received independently, and intercepting at the component level first can significantly reduce whole-housing rework rate. Only the two together balance cost and consistency.
Yes, mainly due to temperature not being equilibrated. When there is a temperature difference between the casting and the workshop, the gas enclosed in the cavity continuously heats and cools during the test, and the pressure curve drifts accordingly, which may both mask small leaks and reject good parts as defective. The correct approach is to let the workpiece rest near the test station until it approaches workshop temperature before testing, or to allow a longer stabilization window in the program, rather than simply loosening the judgment limits.
The core of air tightness testing for control boxes / PDU housings is reliable plugging, stable criteria, and traceability. The CTS C28WE, with dual methods, ambient drift correction and 32 programs, adapts to control box housing testing on multi-model shared production lines; together with custom plugging fixtures, it forms a complete line of defense for the sealing quality of control box assemblies.
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