<snip> that E-stops are not devices intended to provide protection of personnel <snip> since they only provide protection IF they are used. <snip> E-stops do not protect anybody from anything that a panel lock-out can't do much better. If someone is counting on stopping a machine with an e-stop and then intentionally putting themselves in harm's way <snip> If someone is going to argue that hitting an e-stop AFTER someone has already gotten in the way and is being hurt makes it a safety device, that is like closing the barn door after the horse got out. <snip>
E-stops are safety devices.
Case in point: Arm caught in conveyor.
Many conveyors will continue to drag the arm into the conveyor until motion is stopped. The limb does not create enough drag to trip the protective circuits. E-stop cords are provided along the conveyor. They are the only thing the trapped operator can reach and nothing will trip to save them. As a child my arm was caught in compression rollers. It was the E-stop I slapped that released my arm. As it was, the rollers bruised the muscles in my forearm. Had I been slower the rollers would have reached my armpit and started tearing tissues. Just because an accident has started doesn't mean it's finished.
Case in point: Improperly clamped part.
Most machinery does not include a tilt meter like many washing machines include. An improperly clamped part can spin eccentrically until it gets thrown. Attentive operators often notice the problem at cycle start and hit the E-stop. This prevents a thrown part that the machine cannot otherwise detect until after launch.
Case in point: Maintenance
Automated vehicles scan areas in front of them where obstructions are expected. Maintenance people are often in strange positions like pits in the floor or on booms that are not in the scanned area. I've seen two maintenance people hit by such vehicles. One was bumped, the other was trapped by the vehicle. No injuries. I've also seen at least twelve potential incidents stopped by alert people engaging the E-stops.
Case in point: Unknown issues.
Exactly how sure are you that you have discovered all the failure modes of your machine? It's amazing how many times I've often seen operators save people or equipment by hitting the E-stop before damage occurred. Usually the next question asked is "Who would have thought that could be a problem?". And just as often "Who'd have thought someone would be dumb enough to do that?".
Yes, I vote that E-stops are safety devices. NFPA79 says they are safety devices. And I want them as reliable as any other circuit on the machine.