CETA tester-based differential pressure leak testing
Leak testing is a common post-machining step stipulated on technical prints for aluminium castings. We first met this type of specification when machining a double housing for a Bosch electric traction motor, which was designed for applications in electric vehicles.
The electric motor housing through which coolant flows must be sealed, so microporosity is simply unacceptable in this application. A fully automatic leak tester is used for this precise purpose – to detect leaks. The device works on the principle of comparing the pressure in a given volume of the component under test and the pressure in a sealed reference volume. Maximum deviation is 0.02 Pa. The measured values are processed in real time. Testing one cavity takes a couple of minutes. Every test includes a device that enables the enclosure of the volume under test in addition to the tester itself.
The illustrations depict the testing of an aluminium casting for ROTAX where an internal bearing housing is being tested. A volumetric seal is created using a special preparation that makes a perfect seal on both sides. The space is enclosed using a pneumatic cylinder.