How does the High Speed Cold Bump Pull (CBP) test procedure differ from the normal CBP test?

Pull testing at high speed also requires a different setup than conventional pull testing. Because the clamping jaws must have contact with the ball, an acceleration distance between the jaws and the sample is not possible. Therefore constant velocity is achieved by accelerating both loadcell and work holder together (the jaws to bump connection joining the two).

Pull Test Procedure:
1. In this test the alignment is identical to conventional low speed testing.
2. When initiating the test, the jaws descend and grip the ball.
3. The jaws then accelerate to the target velocity pulling the sample with them. The acceleration load on the bond is kept slightly negative (compression) during the acceleration by an air driven piston which drives the work holder and sample upwards.
4. In its upward travel there is sufficient height for the work holder to reach the target velocity; the work holder then confronts a hard stop and the jaws continue moving at the test speed pulling the ball as they do so. The test is complete.