Abstract
A print defect of streaking took place in an offset printing machine after ditches of blanket drums collided with those of proof cylinders. The streaking was visible just after the collision. These experimental features suggested that the defect was caused by the vibration of blanket drums and proof cylinders due to the collision of these ditches. This hypothesis was proved by the experiment that the pitch of streaking coincided with the period of the vibration. The experimental results were confirmed by the numerical calculation based on a simple linear vibration model of eight-degree-of-freedom.
