or is this something that is hard wired into these machines.
Yes its hard wired but for your machine to "react" to it, there has to be something in the "parameters". Otherwise, it would be no more than a on/off situation.
Most machines have a parameter or a bit you can force to "ignore" the door interlocks. FANUC doesn't create this (other than on their own equipment), but they provide an avenue for the OEM to use. So, with that said, its just a matter of reading your electrical books. It's all in there. Find the circuit, follow the ladder, find the bit that's looking for it. No need for a lasered key, sheet metal key, cut off the wires, dangle the interlock from the door while being taped together, etc, etc. Keeps everything "legit".... and keeps the operators from screwing around on the machines. If I see them with a door key, I know its not ours and I destroy it.
The thing to watch for is making sure of the interlock you're shutting off. Some interlocks are specific to a single door, some are for a number of doors, some are for all doors.
Other than that, do as alot of places do... cut the wires, make a sheet metal key, unbolt the key and attach it to the interlock so it doesn't come out, etc, etc.
It's just a part..... cutter still goes round and round....