One-sentence answer: The sealing of a servo drive housing affects the reliability of power devices and circuit boards in oil mist and metal dust environments. With the CTS Sentinel I28 multi-function leak detector, two types of tests—housing air tightness and cavity isolation—can be run sequentially (in-series) at the same station, first judging leakage and then judging air duct cross-communication.
Potting voids and terminal feed-throughs are typical leak points; liquid ingress destroys power devices
If the partition between the cooling air duct and the circuit cavity is poorly sealed, oil mist and dust will be carried by the airflow directly into the power device area, and testing overall air tightness alone cannot detect this.
The bonding interfaces between the potting layer and the housing and terminals are independent and easily overlooked, and defects are often averaged out in whole-unit testing.
The gaskets or O-rings of multi-pin terminals can lose sealing locally under assembly deviation.
Sealing locations: housing parting surface and end cover, terminal feed-through mating surface, potting surface and pouring port, and the partition seal between the cooling air duct and the circuit cavity.Consequences of leakage: intrusion of oil mist and metal dust causes creepage, short circuits, and drive failure; cooling airflow carries contaminants directly into the power device and busbar area; failure to meet the protection rating limits operating conditions.
Why multiple methods in series are essential here. There are two types of problems with different natures on a drive: one is external leakage at the housing, end cover, and terminal feed-through, which is a sealing issue; the other is loss of sealing in the partition between the cooling air duct and the circuit cavity, which is a cavity isolation issue. The latter is almost invisible in an overall air tightness test—both sides of the partition are inside the enclosure, so no external pressure drop is generated when the whole unit is pressurized. But once the seal fails, the cooling airflow will carry oil mist and metal dust directly into the power device area, with consequences as serious as water ingress. Therefore the criteria must be separated: pressure decay judges external sealing, and mass flow judges whether there is an unwanted path between the air duct and the circuit cavity. The potting surface is an independent sealing path formed later in the process, and the bonding interfaces between the potting layer and the housing and terminals also need to be judged in a separate program segment.
In an air-cooled structure, airflow passes through the enclosure. If the partition loses sealing, contaminants are carried by the airflow directly into the power device area. The I28 uses a mass flow segment to judge this path separately, preventing an overall air tightness test from masking the problem.
The potting surface is an independent leakage path and must be judged in a separate program segment, and controlled together with potting layer curing process parameters and visual inspection. Relying only on whole-unit pressure holding tests tends to result in missed judgments and repeated re-testing.
Yes. The I28 supports storage of multiple test programs, saving parameters and test sequences separately by housing model. During changeover, simply call up the corresponding program—there is no need to readjust instrument parameters or fixture cycle time, making changeover faster.
Yes, and it is a critical one. A failed partition seal does not generate an external pressure drop, so an overall air tightness test cannot detect it, but the cooling airflow will carry oil mist and dust directly into the power device area. The I28 uses a mass flow segment to specifically confirm whether the air duct and circuit cavity communicate, screening out this type of hidden risk separately.
The key point for servo drive housings is the separate judgment of air tightness and cavity isolation. The multi-method sequential (in-series) testing and multiple program capabilities of the CTS Sentinel I28, together with dedicated fixtures for terminals and air ducts, are suitable for batch factory sealing inspection of servo drives.
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