Hello,

I wanna make some tubes using prepreg. I tried using shrink tape but unfortunately i didn't manage to roll the shrink tape uniformly and there were some waves on the finished tube.
My question is , can i use heat shrink tube for consolidation? how about battery shrink tubes?
or what alternative solutions do you propose for consolidation?


 




Thank you!

It can work, but leaves a pretty poor surface finish. You also want to be careful, because keep in mind that a lot of heat shrink tubing is design to bond well with epoxy so that harnesses can be sealed or potted. Some don't and will self release ok, but you need to make sure.

Have a look at Soller Composites range of heat shrink tubing, which is specifically designed for composites use. Still leaves a surface finish with a bit to be desired, but does have the advantage of not leaving the ridges that the wrap causes and is of course much quicker and easier to use. For small tubes I still prefer the wrap. For anything over 500mm wide, the tubing is nicer to use.

It may not fix your initial problem either as the waves or ripples are normally caused by not having enough tension on the material in the first place causing it to ruck up when the pressure from the tape is applied; try to ensure the material is really well consolidated, within reason, onto the mandrel before applying the tape or trying with the heat shrink tube.

If you don't debulk your stack of prepreg as you wrap the layers (debulk with pull-tape on the zeros - like every 600-1000g of material) then there will be excess material because loose layers are going over loose layers and the circumference gets unreasonably big.  Then you tape-wrap (or shrink tape) and it gets all wavy because there isn't any place for the materiel to go.  Either that or your tape shrinks inconsistently or has uneven pressure.  Most tape wrapping of tubes is done with non-shrinking plastic tape pulled stretched.  Often this is vacuum bagged for curing - and also often autoclaved.  You could probably put your (any kind) heat shrink tape over a wrapped release film and not worry about it getting stuck.

Check out this tape:  https://www.flexiconpacific.com/composite-tubing-release-films/