Cover Screw Torque
Tightening the cover screws of an outdoor receiver to the manufacturer's value and in a way that spreads the seal pressure evenly at every corner. Too little torque does not compress the seal fully and lets water in; too much torque strips the thread seat in the plastic enclosure or warps the cover, which again opens a leak.
Cover sealing relies on the seal being compressed evenly all the way round. If one screw is tightened more than the others, the cover bends slightly; at the opposite corner the seal pressure drops and water gets in exactly there. That is why the screws are tightened not in sequence but in a diagonally opposed pattern, in two passes: first all of them just to contact, then to the final value.
- Sign of insufficient torque: moisture inside the enclosure after rain, and the seal leaving no clear imprint along the cover edge.
- Sign of excessive torque: the screw spinning free, whitening or hairline cracks in the plastic enclosure, permanent flattening of the seal.
- Practice: on plastic enclosures the values are typically low, on the order of 1 N·m; if the manufacturer gives a value, use a torque screwdriver, if not, even it out by hand feel and in a diagonal sequence.
A cracked enclosure does not carry the IP declaration no matter what the code says; the cover screw is therefore a permanent item on the maintenance list.
The context in which this term is used: Wireless Crane Remote Control Selection Guide