I'm having trouble with shipping an electronic enclosure. During the transport the wires get loose from the screw terminals of the PCB due to vibrations. 22 AWG stranded wires and the terminals is here.
Is there a practical way to secure and reduce such possibility rather then giving a lot of torque? Such as glue epoxy etc?
I experienced a similar problem. It seems that trying to compress a bundle of stranded wire in a screw terminal is less than ideal, as the wires spread about and can have high spots where they cross.
I found that they make ferrules for terminating wire ends. They work better because crimping the metal tube captures all the strands and holds them tight. Then the screw terminal only needs to hold the crimped tube.
Sample images taken from Adafruit
The screw terminal's job is only to make a contact, not to fasten the wires and prevent them from flapping around... With vibration, if you don't use some form of strain relief, the wire can either break or get loose.
So... you need to clamp the wires to something, preferably to the PCB since that makes it much easier to take it out of the enclosure without having to disconnect everything. It can be as simple as two holes in the PCB to thread a ziptie through and hold the wires, or a PCB mounted cable clamp...
Random example:
Is there a practical way to secure and reduce such possibility rather then giving a lot of torque?
Ideally you should be tightening those terminals using a torque-controlled screwdriver, per the torque given in the datasheet of the terminal block. That's the starting point to this discussion. Only if that fails you'd be justified in looking for other solutions.
It's hard to be sure that you have tightened those terminals sufficiently unless you use a proper tool.
The terminal blocks themselves must be designed to accept stranded wire. Not all are. The datasheet should specify whether only solid wire or a ferrule is acceptable, or is ferrule-less stranded wire OK as well.
The wire size (AWG or cross-sectional area) must fall within the acceptable wire size for the terminal block. Note that this size range may be different for solid and stranded wire.
So I would say that if the wire gets loose in spite of you using correct torque and correct wire type and size for the terminals, then you should talk to the terminal block manufacturer's customer support, as it would indicate it's a problem with their product. It's IMHO more likely that you're using insufficient (or excessive!) torque, or not a wire type/size that the terminal is rated for.
Most terminal blocks are rated for negligible wire loads, i.e. the wire should be exerting almost no force on the terminal block. If you have long runs of unsupported wire, the inertial forces will exceed what the terminal block was designed for, and the wires may get loose.
You should do an in-house pull-out force test for your terminals to get an idea of what sort of static pulling force the terminals support. The repetitive/cyclic pulling force that's allowed will be much lower than that.
