Cracking observation is a visual assessment, and the standards treat it that way: the specimen is examined at the bend after reaching the specified angle.

What the machine contributes is that every specimen reaches that angle the same way, over the same roller spacing, at the same rate. Without that, two operators can reach different verdicts on the same material.

The recorded force and angle curve gives the objective record alongside the visual result. The angle and the mandrel the examination is made at come from the method itself, most often ASTM E290 or ISO 7438.