Making Complex Carbon Fibre Tubes Using a Split-Mould

[Music] in this video we're going to be looking at the tube molding process in detail in the recent video we did making a carbon fiber bike frame some of the fundamentals of this process were lost in the overall complexity of the project so hopefully by using this simple shape we can demonstrate very clearly how the laps work and the two halves join and how to make the tubular vacuum bag this process is best suited to making fairly complex structures whether that's a bike frame or an induction system or a component like this it provides you with a molded outer face and is made using split molds if you're just looking to make a straight or a tapered tube the roll wrapping process might be more suitable we do have a video dedicated to this subject entirely so if you've not done so already do go and check that out the first step as with any new prepreg carbon fiber part is to make a set of templates so we're going to be using masking tape for this and that will give us a rough template that we can refine a little bit later on as the masking tape doesn't unfold and flatten in the same way that prepreg will we're going to oversize this slightly and then we're going to adjust that on the mold and then from there we can make a very precise pattern the first pie is now in the mold this is the pie that's going to be trimmed flush with the flange of the mold so I'm going to do that now but it also saves the offcuts that I get transfer them onto the backing ply and that will then give me a very precise template for exactly how the carbon fiber drakes into the mold so the future parts that I make will be much more precise and won't require adjustment this is the precise template for the surface of the mold so for the side that's going to have the laps that extend into the other one we've got to make the three plies that we're going to be using slightly larger so the first one will be five millimeters larger the second one ten millimeters larger and the third one fifteen millimeters larger to provide that staggered lap into the top so we'll mark goes up and cut those now I've got the three pliers marked out for the extension side so we've got a 5 millimeter 10 millimeter and 15 millimeter extension so that's one side of the mold the other side of the mold we need to reduce the size by approximately three millimeters in this case two which will leave us with a bit of a lap the first play on this side of the mold finishes flush with the flange so to make sure we get a good join between the two sides this one is going to have the extension of five millimeters so I'll lay this into the mold now and it'll be left with a protruding section here which will subsequently I lap on to this ply here on this side making the two halves join with the first plies laid into both halves of the mold we've got this side cut flush and this side with the small extension now that is what's known as a lap and you can see how that works when these two come together that lap goes inside the other mold half and then when the vacuum bag goes on it will apply pressure to that and create a very strong join between the two halves there might be quite difficult to see hopefully you can just about make out the second ply just down from the surface here so that's staggered away from the first and then the third ply which is yet to go in will stagger down a little bit lower again all three pies are now laminated into both mold halves so on this side which starts flush with the flange of the mold we've got the first second and third place staggering down like that and then to pair up with that on the positive side we have these extensions again the one two three layers here which give us the join between the two halves we're now moving on to the vacuum bagging here easy composites we've got a range of tubular bagging films suitable for internal vacuum bagging like we're doing here it's important that you choose a size of vacuum bag which is quite a lot larger than the diameter of your tube that ensures that you've got plenty of room for the bank to expand without the risk of it bridging our tubular bags are self releasing which means they can be put directly against the surface of the prepreg without necessarily having to use a peel ply or a release film they've also got a fold system which means that they can expand very easily sliding against themselves this further reduces the chances of getting bridging prior to closing the mold it's vitally important that you keep these laps folded in obviously you don't want them folding out and becoming trapped between the two mold halves but also it's quite easy for the top half of the mold to catch these causing them to crease or wrinkle and that will compromise the strength of the joint so it's just a case of carefully leaning them in and checking that when they relax they don't open out too far on a small molding like this it's relatively easy to close this without really risking this getting pinched but on large molds it can be quite useful have tools available to just come in through the edge and keep those pressed inwards vacuum bagging internal geometries such as this tube does require a slightly unusual vacuum bag to be made hopefully seeing it on a relatively simple shape like this should make it fairly easy to understand the first thing I'm going to do is wrap this part in breather this serves two purposes the first is that it creates an air path so when the vacuums applied the air can easily escape and the other thing it does is covers up any of the sharp edges and corners reducing the risk of the vacuum bag becoming punctured just before pulling vacuum on this bag we can see relatively clearly now how it's going to work so when we draw the air out of this outer bag it will draw out between the green bag that passes through the center and that will basically suck those two elements tightly together so the inside bag will be being sucked onto the inside of the tube and then the outer bag will be pulling down onto the outside of the mold so that's giving us the consolidation that we need with the cure complete and the park cooled to room temperature the bag can be removed and the internal vacuum bag extracted as this bagging material is self releasing the extraction is usually very easy it's worth mentioning that internally vacuum bag parts like this are most easily and commonly made with prepregs and whilst it might be just about possible to use a wet layup or infusion process the added difficulties that would be encountered would make it impractical for nearly all internally vacuum bag projects after a quick debo and trim the final component is complete if you need a perfect cosmetic finish with no visible flash lines parts can be sanded down with 400 grit wet and dry and painted with a conventional clear coat or lacquer thanks for watching I hope you've enjoyed this video as I mentioned right at the start if you're just looking to make simple straight tubes the roll wrapping process might be more suitable we do have a video covering that topic specifically so that's well worth checking out if you want to see the molding process used in something much more complex on video where we make a downhill mountain bike is well worth a watch if you want to support our channel keep us making more content like this we always appreciate a like and a subscribe and do remember that all of the materials said the X Pro prepregs and the tubular vacuum bags are available on our website you

Channel: Easy Composites Ltd

Views: 2,669,110

Keywords: carbon, fibre, fiber, tube, mould, prepreg, pre-preg, split mould, guide, tutorial, vacuum, bag, internal

Id: bBbOUDDJv4Q

Length: 10min 56sec (656 seconds)

Published: Tue Apr 21 2020