One-sentence answer: Electric drive reducer housings rely on sealant applied to mating faces, oil seals at bearing bores, and threaded plug seals to contain gear oil. Broken sealant beads, through-going casting micro-porosity, or poor oil seal lip assembly can all cause oil seepage, leading to a drop in oil level and lubrication failure of gears and bearings. Using the CTS Sentinel A28 differential pressure leak detector to compare a master part against the part under test can largely cancel the reading drift caused by residual heat of the workpiece after sealant curing, making it suitable for 100% inspection on high-volume production lines.
Mating faces are sealed by robot-applied sealant plus bolt preload. Broken beads, off-center sealant lines, and sealant layers squeezed thin after clamping cannot be seen in the finished assembly appearance; they only show up after the oil cavity is pressurized.
Bearing bores and oil seal seats are secondary machined surfaces. Subsurface pores that were originally closed only form oil seepage paths after being cut into, and incoming material inspection at the supplier cannot cover this.
Changing the tightening tool or the torque strategy on the same housing can change the sealing state, so the production line needs test data as a backstop.
After operation, oil temperature rises, and the requirements on sealing faces are higher than under room-temperature conditions. A micro-leak at room temperature is amplified under hot conditions.
The sealing locations are concentrated at:
Consequences of leakage: gear oil slowly seeps out, the oil level drops, and bearings and gears enter boundary lubrication or even dry friction, causing abnormal noise, pitting, and seizure; at the same time, oil seepage contaminates the vehicle chassis and the road surface, triggering OEM requirements for rectification of the sealing components.
The reducer oil cavity is a small-volume, high-volume workpiece, and workpieces after sealant application often carry residual heat. The difficulty in judgment is distinguishing a true leak from temperature drift:
If the same station also needs to test the blockage state (Occlusion) of the breather plug, or needs to run pressure decay and vacuum decay in series within the same instrument, the multi-function single-station model I28 can be selected.
Wait until the sealant reaches the curing strength specified by the process before testing. If pressurizing while the sealant has not set, the gas may push the sealant layer open and cause a false leak, or it may push open the seal of a conforming part. The specific interval should be calibrated through joint trial runs of sealant parameters and test results, and then written into the work instruction.
During testing, use a dedicated plug to temporarily seal the breather plug hole so that the oil cavity becomes a closed cavity before pressurizing, and reinstall the breather plug after testing is completed. The open flow of the breather plug itself is another type of test item and should not be mixed into the same test program as the air tightness judgment.
It is recommended to first perform an overall test on the complete unit cavity. After a failure is determined, use segmented plugging to narrow the range to one of the mating face, shaft seal, or threaded plug, and then rectify that specific location. The multiple test programs of the A28 are well suited to this segmented localization process.
Sealing testing of electric drive reducer housings is essentially about intercepting invisible sealant and casting defects before assembly. The differential pressure comparison structure of the CTS Sentinel A28 can maintain stable judgment under residual heat conditions. Combined with custom plugging fixtures and multiple test programs, it meets the 100% inspection and segmented localization requirements of reducer high-volume production lines.
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