I was in an auto manufacturing plant many years ago. Got a close look at a 1000 ton forging machine for making CV joints. The press cycled about 1/second, and it sounded like a heartbeat you could hear and feel in your feet, throughout most of the plant.
The progressive dies were held in place by large hex head cap screws, at least 1" in diameter. They replaced all the bolts every 6 months or so, because they couldn't torque them tight enough to meet the bolt manufacturer's torque spec. I don't remember the exact number but it was well north of 1000 ft*lbs. The problem wasn't torqueing the fasteners, but rather that they'd warp the steel dies and mounting plates enough to warp the forging cavities and the parts made by the equipment. So they left the bolts "loose". This would all some movement which would fatigue the bolts. After more than 6 months in service, the hex heads would start popping off the bolts. Some time prior to my visit one of the factory guys got clipped in the head when one of the bolt heads popped off. He was wearing a plastic bump cap; which saved him from having his head split open. That's what started the factory replacing the bolts every 6 months.
