Braiding machine initial yarn placements

[eatfood]

For braiding machines of ropes or braiding over preforms, how is the initial yarn loaded and held before the braiding process takes place? Is there a yarn puller that you hook each individual yarn from each bobbin to the holder? Is this normally done manually or is there an automated way to load them? Does the initial hookup location of the yarn matter? (i.e. does it become self correcting over time so you just need to bunch them together kinda initially then cut off the bad parts)?

Also, what do you do to the terminal ends of the braids to secure them and prevent them from unwinding?

 

[Compositepro]

The details depend on the design of the machine and what you are braiding. Often one bunches the yarns together and clamp them for start-up. Braids are usually taped with a suitable tape an cut at the center of the tape.

 

[mrsdesign]

Compositepro is correct - tapes are often the simplest method for yarn placement.
The preform or mandrel is often held in the braiding machine using a pin and if you design it with a suitable lead-in then you can use this as an anchor point - if you braid a high-angle initially over this pin in a forward-reverse-forward direction then you get a really well locked braid which should resist slipping. It is advisable to braid some excess material to allow the braid angle to become uniform - a few inches is usually enough - but can be determined experimentally.
If you wish to preserve tension in the braid and prevent the preform from puffing out when cut then you can design some tooling to act as a clamp, this can also give a good edge for trimming and can be used for preform placement in your RTM tool - if this is your preferred method of injecting resin. I have done this pretty successfully in the past.