The Junker Test (DIN 65151 / ISO 16130): How Vibration Resistance Is Actually Measured
Every fastener marketing sheet claims "vibration resistant." The Junker test is how those claims are forced to prove it.
What the machine does
A bolted sample is clamped to a plate that oscillates transversely — sideways relative to the bolt axis — under servo control. Displacement is pushed to the slip limit while a load cell continuously records residual preload. The test runs until preload collapses or a fixed cycle count ends.
Reading the curve
The plot of preload versus cycles tells the story: an unprotected bolt loses 80% of preload within a few hundred cycles once slip begins; a good locking system retains 60–80% through the full run. Beware of reports showing only "cycles survived" without preload axis — the shape of decay matters more than the endpoint.
Using the test in procurement
- Ask for the standard cited (DIN 65151 or ISO 16130), amplitude, and clamp length — results are not comparable across setups.
- Test the real joint: coating, hole clearance and surface finish all shift the slip point.
- Require at least three samples; locking performance has statistical spread.
Topprecision validates its locking inserts and patch screws on Junker benches and supplies the raw curves with test reports, not just pass badges.
