Case Study: Precision Bearing Seal Integrity — Eliminating Thermal-Drift False Rejects at Line Speed
Industry: Automotive | Hardware: LD Series Differential-Pressure Leak Tester + LT-D02 External-Clamp Quick Connector
| Specification | Value |
|---|---|
| Test Pressure | 12 kPa |
| Leak Threshold | ≤ 0.1 kPa pressure decay |
| Cycle Breakdown | Charge 4 s / Stabilize 5 s / Measure 4 s / Exhaust 1 s |
| Total Cycle Time | ≤ 14 s |
| Detection Method | Differential pressure |
Problem
Sealed bearings for automotive drivetrain and electric motor applications require 100% end-of-line leak testing at 12 kPa — a pressure level at which thermal expansion of trapped air (ΔT = 1 °C produces ΔP ≈ 0.04 kPa in a small bearing cavity) directly competes with the ≤0.1 kPa acceptance window. Traditional direct-pressure methods generate chronic false-reject rates of 3–8% on high-volume bearing lines due to thermal drift during the stabilization phase.
Solution
The LD Series differential-pressure tester uses a reference-chamber bridge to achieve real-time thermal drift compensation. Any temperature-induced pressure change affects the DUT and reference volume identically, canceling in the differential measurement. This reduces the effective noise floor to < 0.01 kPa, providing a 10:1 signal-to-noise margin against the 0.1 kPa acceptance limit. The LT-D02 external-clamp connector seals the bearing OD in a single-hand operation, providing consistent seating force across operator shifts.
Result
- ≤14-second total cycle time — inline capable at typical bearing assembly line rates of 200+ pcs/hr
- Thermal-drift false-reject rate reduced from 3–8% (prior direct-pressure method) to < 0.1%
- ≤0.1 kPa leak limit enforced with 10× measurement margin
- Poka-yoke output signal (PASS/FAIL + data logging) compatible with inline SPC systems