Summary

In composites, vacuum bagging is the next step up from an open-cured wet layup, and it comes with some significant advantages. In this webinar, we'll talk through all the foundational knowledge for vacuum bagging and outline the practical steps to bag your own parts.

00:00 Hey team, Connor here from HPA.
00:01 Welcome to another one of our webinars.
00:03 This week we're going to be having a bit of an introductory look into vacuum bagging for our composites work.
00:10 So, we're going to start off by just having a quick discussion of what vacuum bagging is and why it's done and a few of the different applications or different ways we might do it.
00:20 And then we're going to do a bit of a practical demonstration as well to look at what's involved in vacuum bagging, wet layups, the materials involved and what the process looks like.
00:32 So, we'll get straight into it and we'll first just talk about what vacuum bagging is and why do we use it for those of you who are pretty unfamiliar with the process.
00:42 So, essentially what it means is we are enclosing our layup in a sealed vacuum bag and that allows us to then pull a vacuum on it.
00:53 You might be familiar with you know packing up clothes into sealed bags and you can pull the air out of it and it seals it up nice and compact.
01:01 So, it's a very similar kind of process and you can actually use those bags in some cases as well.
01:07 But basically if we pull a hundred percent vacuum on the bag, so we pull out all the air and everything that's inside the bag, we essentially end up with one atmosphere of pressure bearing down on our layup.
01:20 So, one atmosphere about one bar or 14 and a half psi somewhere around there of pressure bearing down on the layup.
01:29 So, compressing it from really even distribution from all angles and so on.
01:34 So, if we think about a wet layup, which is kind of the the entry level into doing composite work with fiberglass, carbon fiber, carbon kevlar, flax composites, whatever we're talking about in terms of reinforcement, the wet layup or hand lamination is really the the entry level into it where we are wetting out the reinforcement by hand with our resins, and then we're going to put it in the bag.
01:58 So, we're simply going to fill that back up with some insulin and laying that up wet and then allowing that to cure And if we talk about an open cure, so we've got our mold or whatever we're laying up our reinforcement into, an open cure is where that's just you know the the back of the mold is expressed to atmosphere and it's just curing like that.
02:17 The vacuum bag is essentially one tier up from that I guess, Yes, in terms of complexity, accessibility, and then also probably the results that we get out at the other end should be one step better, and if we think about our kind of four key composite processes, construction processes, that would be a wet lay-up with an open cure, a wet lay-up with a vacuum bag, and then resin infusion and pre-preg stuff as well, and we'll get back to that in just a moment.
02:49 So, if we're comparing a wet lay-up open cure to now a wet lay-up with a vacuum bag cure, what we're going to get with the vacuum bag is better consolidation, so that's essentially consolidating our lay-up, or the layers of our laminate as they cure, together and also into the mould surface.
03:10 That's going to reduce the chance of voids in our lay-up, and bridging, if we do everything right as well, where we basically have a bit of a corner, a corner in our mould, and then the reinforcement or the bag or whatever material we're working with is too short to lay into that, and it'll kind of bridge across it.
03:30 If we have the vacuum pressure it helps us kind of drive that into the corner, again if we do it all correctly, but reduce the chance of voids between the layers in our laminate as well.
03:39 And those voids essentially, you know, open spots obviously have no resin or reinforcement, or maybe they've got resin in them, but no reinforcement are basically weak spots.
03:48 And places where our lay-up or laminate will de-laminate and fail.
03:54 In better consolidation we also will end up probably with a slightly thinner laminate as well, for the same amount of reinforcement in it.
04:03 We'll also get a better surface finish, so that as we de-mould it, and pin holes is reduced with the vacuum bagging over an open lay-up, because we're basically again just consolidating that all into the mould surface.
04:20 And then we'll also generally end up with a better fibre to resin ratio.
04:25 And this is kind of one of the ways that the performance, I guess, of a composite, everything else being the same, is measured.
04:35 So, we want a lower fibre to resin, sorry, a lower resin to fibre ratio.
04:42 So, we have less resin in the part for the same amount of fibre.
04:46 If we're talking about a wet layer.
04:48 If we're talking about a lay-up that might look like 60-40, 60% resin, 40% reinforcement by weight.
04:56 If we're talking about resin infusion, we might be looking at 50-50 or down to 40 -60 the other way.
05:03 And then pre-preg parts can kind of drive that as low as 30% resin content for autoclave parts and aerospace at the highest kind of level.
05:15 Essentially, our vacuum bag allows us to achieve a better surface finish.
05:18 A better resin to fibre ratio by squeezing over an open cure, by squeezing out the excess resin into the bag or into a bleeder layer that we'll talk about soon.
05:31 And basically what that means is we end up with better specific mechanical properties.
05:37 So, what I mean by specific is mechanical properties per unit mass.
05:42 So, we'll end up with a better strength to weight ratio and stiffness to weight ratio.
05:48 And then we have that better resin to fibre ratio.
05:51 And this is all compared to a wet lay-up.
05:54 But vacuum bagging also forms the foundation behind doing our resin infusion as well as our pre-preg work.
06:04 Because we use vacuum bagging to do a resin infusion and we also use it to do the pre-preg work.
06:09 Even if we're using an autoclave, which is like a big pressure vessel to consolidate our pre-preg stuff.
06:15 We still use a vacuum bag to do the debulk first.
06:19 And the part still goes into cure in the vacuum bag.
06:23 So, if you're just getting into composites, you might do some wet lay-up stuff.
06:28 And then if you want to step it up and do any of those other processes, then this vacuum bagging process is going to be vital.
06:36 Whether you're doing a wet lay-up, a resin infusion or any pre-preg work.
06:40 It's really a fundamental skill that you need to have to be able to do any kind of higher performance composite work anyway.
06:47 But it's quite easy and accessible depending on how you do it.
06:52 So, we talked a little bit about what exactly it is.
06:56 We're enclosing our lay-up in a vacuum bag.
07:02 And there's two different main ways we can do that.
07:04 One would be with an envelope bag.
07:07 And that, as it suggests, is we make an envelope out of the bag.
07:12 We slide our lay-up in it.
07:13 So, typically we have our part laid up maybe in a small mould.
07:17 We slide that in the bag.
07:19 We seal that up.
07:20 Just like you would with those clothing vacuum bags that we mentioned at the start.
07:25 That would be an envelope bag.
07:27 And then the alternative and what's more so used in...
07:31 So, that would typically be used in a wet lay-up.
07:34 Depending on what we're doing.
07:35 And also pre-preg parts for an envelope bag.
07:38 And then the alternative, which would be something we do a lot of the time with resin infusions and so on.
07:43 Is called a tool sealed bag.
07:45 So, that's when our mould has a flange surface around the edge of it.
07:50 And then we seal the bag against that.
07:52 So, the bag and the mould basically form the enclosure.
07:57 And what we're going to look at doing today is essentially a tool sealed bag.
08:01 So, let's move on from there and just talk about the materials that we use for the vacuum bagging.
08:09 Or in other words or also known as the vacuum bagging stack.
08:13 In some cases because we're stacking up the material.
08:16 So, what I have under my computer here is a bit of melamine.
08:20 And essentially just wood with a kind of vinyl coating on it.
08:26 And we can use this as a mould for making nice flat carbon fibre sheets.
08:35 You can also use other flat pieces of metal or mirrors or pieces of glass or things like that as well.
08:42 Typically if the surface texture of the mould is going to be transferred to that of the part.
08:48 Which can be polished and flat afterwards.
08:50 But it's nice to have a nice smooth glossy finish to start with.
08:57 But we could be talking about the mould surface being anything here.
09:01 So, if we talk about a traditional mould.
09:04 That would be a fibreglass mould with a gel coat surface or something like that.
09:08 But the mould is essentially you know the negative of the part.
09:11 That we're creating.
09:13 So, we have the mould surface and then next up on the mould surface.
09:17 Not really a material but if we just look under the overhead here.
09:23 This is Meguiar's Miracle Gloss Wax.
09:26 So, we'll have a release agent that we apply to the surface.
09:30 Like this is kind of the traditional approach using a mould release wax.
09:35 And what that's going to do is prevent the material or the cured laminate.
09:40 From sticking to the mould surface.
09:42 And it means after it's cured we'll be able to release it.
09:45 And remove our part from the mould.
09:48 This is one of the options like I said the kind of traditional approach to use wax.
09:52 But we can also use alternatives like chemical release agents.
09:59 Which are semi-perms as well.
10:02 So, basically we can apply them to the surface in lots of layers.
10:07 And maybe just top it up with wax.
10:10 One layer each time because they kind of last.
10:12 And we can get multiple pulls from the same release agent.
10:17 Or the other alternative that's often used is PVA parting film.
10:21 So, that shouldn't be confused with PVA glue.
10:25 Naturally they work almost opposite to each other.
10:27 But that's a parting film that we basically brush or spray onto the surface.
10:33 And it kind of dries and creates a film barrier again.
10:38 Which helps us release the parts.
10:40 Apart from the mould surface.
10:41 So, that's our release agent.
10:43 Again, not really a material.
10:45 But the next thing onto the mould surface.
10:50 So, next typically for a wet lay-up we wouldn't use a gel coat.
10:55 So, we'll kind of skip that for now.
10:57 The next thing would be our reinforcement.
11:00 So, I've just got two sheets of carbon twill here.
11:06 But again this could be a non-woven.
11:10 Something like a non-woven material.
11:11 Something like chop strand mat.
11:12 Fiberglass.
11:14 It could be carbon kevlar.
11:17 It could be straight kevlar.
11:19 It could be flax.
11:19 Whatever we're talking about.
11:21 We have our reinforcement in there next.
11:23 And typically we're going to be building up multiple layers of that reinforcement.
11:27 It doesn't need to be two layers of the same twill like we have here.
11:31 It could be a layer of twill on the surface.
11:34 Or spread toe.
11:36 Or a plain weave.
11:37 Or something like that.
11:38 And then typically followed by something like a unidirectional or biaxial backing layer.
11:44 Which doesn't look as good but provides a lot of the mechanical properties we're after.
11:49 So, we have our reinforcement.
11:50 And naturally if we're doing a wet layup that'll be wet out with resin as well.
11:55 So, the typical kind of process like that is once our release agent's down and cured and all that's done.
12:01 And our mould surface is ready.
12:03 We would brush our resin onto the mould surface.
12:08 We would lay up our first layer of reinforcement.
12:12 And wet that out.
12:13 And then lay down the kind of consecutive layers of reinforcement.
12:17 Wetting them out as we go.
12:18 And that's the general idea behind a wet layup.
12:21 There are other ways to do it.
12:22 But that's the kind of main process.
12:24 So, we've got our reinforcement down.
12:26 And it's wet out.
12:27 Then the next layer would be our peel ply.
12:31 So, the peel ply is like a nylon.
12:38 It's a nylon woven sheet.
12:39 So, it's a very kind of fine weave here.
12:42 And what the peel ply, the main purpose of the peel ply is to stop the next layers that are going to come from bonding or of kind of impregnating themselves in our reinforcement.
12:54 And it means that afterwards, after it's cured, we can peel the peel ply back off the surface along with the rest of the consumables.
13:03 I'll just skip ahead slightly to our breather layer.
13:06 So, this is breather material or bleeder here.
13:08 And you can imagine this is kind of a non -woven mat.
13:12 If this got wet, got wet out with resin and was forced into the back of our or just in contact with our reinforcement, that would kind of embed itself in there and be a real pain to remove.
13:28 Probably not impossible, but it would leave a lot of this material in the back.
13:33 So, that kind of peel ply creates that back.
13:36 The peel ply also serves a couple of other purposes.
13:43 The main one, like I said, is to kind of stop things from bonding it to it and allow us to tear the consumables away from the part at the end.
13:52 But it also will leave like a nice, consistent textured surface on the back of our part.
14:00 So, typically, if we do, for example, our wet layup and then it cures, open, we'll kind of get quite a rough texture on the back.
14:09 And the peel ply on that surface will essentially create a really even textured surface to the back that one, looks a lot better.
14:19 And two, it's actually really good if we're then bonding other parts to the back of the surface because it's kind of has this nice texture or keyed surface to it.
14:29 So, that's one thing.
14:31 And then we'll talk about another material here as well, kind of at the same time.
14:37 But one of the purposes of the peel ply, because it is kind of a breathable fabric material, so it has a lot of little gaps in it.
14:46 What it will do is it will allow resin and air to pass through it.
14:50 So, as the vacuum bag compresses the layout and squeezes it, the excess resin will be able to flow out through the surface of the peel ply.
15:05 And also pull those kind of air bubbles and voids out of the layout and get better consolidation.
15:13 The other material that I have here, which can be used in conjunction with this or at the same time over top of it for a little bit kind of better control, but this is a perforated release film, as you can see by the title or the writing on the bag here.
15:30 And it's essentially a plastic film and it has, you might be able to see just slightly the kind of texture on the surface there is lots of really small holes.
15:41 So, it essentially does a similar thing.
15:44 The purpose of this is not to prevent that bonding and be able to peel away, but this is more for getting better control over the flow of air and resin through that kind of boundary layer and then into the bleeder.
15:58 So, we could use one of these.
16:00 We have no perforations to stop that flow of resin or bleeding out of the the layout or we could use one with like more holes, for example, to really promote that.
16:14 But that's kind of the purpose or the difference between a release film and the peel ply.
16:20 So, you can do if you're doing a lot of stuff of the same parts, you can kind of use these with each other and different types to kind of tailor the.
16:30 Performance of that bleeding function from the the layout.
16:36 You do not need this in every case, but it can be used as well.
16:43 It just depends kind of what you're trying to do for a really cheap and quick layout.
16:48 I'd kind of recommend the reinforcement, the peel ply and then skipping this and moving on to the next layer.
16:55 So, the next layer would be our breather or bleeder.
17:01 So, I guess if you're this is not used in a resin infusion, but it is used in vacuum bagging or debulking of prepreg parts.
17:11 So, the breather, as the name suggests, is kind of a path for airflow.
17:17 So, as we are pulling air or pulling a vacuum on our bag, the air is will flow through this layer and to the vacuum.
17:29 So, basically, our vacuum port needs to be in contact with this, and we'll see that soon when we kind of lay this all up together.
17:41 The other function for it is to work as a bleeder layer, and that's more specifically just for wet layups.
17:50 So, what that does is as that excess resin comes through the peel ply here, this is basically just catching it and absorbing it.
17:59 So, this is getting wet out and reducing the kind of resin content in the part.
18:07 Hey guys, sorry about that.
18:08 Just had some technical troubles.
18:10 We'll just pick up where we left off.
18:12 So, the last layer was that breather or bleeder layer.
18:15 And then next, we have our vacuum bagging film.
18:18 So, there's a few different types of vacuum bagging film, but this is the typical one.
18:23 It's essentially a nylon kind of based film.
18:28 And this one doesn't have much flexibility to it.
18:33 So,me are sold with that flexibility, and that kind of helps with their ease of use.
18:38 Although in some cases it does obviously reduce the amount of force that that then is putting on the part as it kind of consolidates it.
18:47 So, it's a bit of give and take there.
18:49 But we have our vacuum bagging film used to create our envelope bag or our tool sealed bag.
18:55 And then the other part that goes along with that.
18:59 Is, I don't mind my deformed roll of tape here, but our bagging kind of gum tape.
19:08 So, again, very gummy kind of stretchy tape that's great for sealing to surfaces and to our bag.
19:18 So, we'll be using all of that in just a moment.
19:21 And we'll get into a bit of a practical demonstration of the process.
19:28 So, if you have any questions that have come up during this or during the next kind of stage, feel free to ask them in the chat and I'll do my best to answer them at the end.
19:38 Anything kind of composite related or specifically related to today's discussion.
19:43 Cool.
19:44 So, we have our stack down here already.
19:46 Got our peel ply covering all our reinforcement.
19:49 We'll assume I've wet this out with resin.
19:52 A little bit tricky to do that, you know, with a mask on and the microphone and everything live.
19:57 And while the resin is going off.
19:59 We have this kind of time pressure.
20:01 But we'll assume that's all wet out here and we're making some flat carbon fiber sheets.
20:05 We've got our peel ply down.
20:07 We might have our perforated release film on top of this.
20:10 And then we have our breather layer here as well.
20:15 So, the next step, what we're going to do for our tool sealed bag.
20:21 If we're doing an envelope bag, we'll probably kind of cut up a bit of an envelope of film.
20:27 A lot of the films come in what's called lay flat tube.
20:30 Which is essentially a tube of bagging film where it's already kind of joined on two edges.
20:38 And then we only need to seal two of the other edges.
20:41 Makes the process a little bit easier.
20:44 But we're just doing a tool sealed bag in this case.
20:46 So, the bag is sealing to our tool or our mold.
20:50 Just get this computer out of the way.
20:54 So, what we're going to do is start off by taping down the perimeter of our tool.
21:00 And that's just in this case going to be just outside the consumables here.
21:05 Outside the breather layer.
21:07 But this might be to the kind of flange of our mold and so on.
21:12 And the process is a lot simpler when you have a circular roll of tape.
21:20 That's not...
21:24 being squished to one side.
21:26 We're just going to lay that down to the flange there.
21:29 And then when we get to a sharp corner like this.
21:32 There's kind of two options.
21:33 One is to just tear the tape slightly like that.
21:37 And then the... tear the backing paper rather.
21:42 And then the tape will bend like that around the corner.
21:49 Then we can lay that down.
21:51 The other option.
21:53 Which I'll show you at this back corner here.
21:56 It's a little bit... You can just tear this.
21:59 But it's a little bit easier to cut it.
22:01 Is to cut it and then we just pull back the backing paper slightly.
22:06 And then that next layer can just go straight on over that.
22:11 And as long as we press that down nice and firm.
22:13 That will seal to itself.
22:17 And come along the side here.
22:21 And then again.
22:23 Just tear the backing paper slightly.
22:26 Turn that 90 degree corner.
22:32 And come up to the top here.
22:38 Pull back the backing paper slightly.
22:42 And just overlap that.
22:44 And then...
22:46 I'll just cut that.
22:48 As well.
22:49 And what we want to do is press that down nice and firm.
22:53 To the flange.
22:54 Or the mould.
22:57 There.
22:58 We'll come back around and probably do this a couple of times.
23:01 Because it's really important that that seals really well.
23:05 Down there.
23:07 Cool.
23:08 So, what we're going to do next is add some features called pleats.
23:13 Which aren't really necessary for a flat tool like this.
23:17 Although it can be helpful in some cases.
23:20 Depending on what we're laying up inside it.
23:23 So, the purpose of this.
23:24 The purpose of pleats is essentially as you'll see.
23:27 To increase the bagging material that we have for our vacuum bag.
23:33 While keeping the same perimeter around the outside.
23:36 And that might be needed if we're working on a mould with details.
23:42 That kind of sits proud of this perimeter surface.
23:46 Where we have our tape.
23:50 Anything with kind of irregularities in it to be honest.
23:52 Or big cavities into the mould as well.
23:56 If you think about using a bucket for example as a mould.
24:00 And we taped around the top of it.
24:03 And then if we just did our bagging film over that.
24:07 And taped to that surface.
24:08 As we pulled the vacuum.
24:09 It would try to stretch down.
24:11 But it's not going to consolidate right down into the bucket.
24:15 So, what we need is more bagging material for the perimeter there.
24:19 That's kind of an extreme case of it.
24:22 So, every time with our moulds we need to add these pleats.
24:25 To kind of do that.
24:27 So, I'm going to do some relatively small pleats.
24:29 In this case because it's such a flat bag.
24:32 Just to kind of illustrate how that works.
24:37 So, what I'm going to do to start with.
24:39 Is just cut a bunch of these sections.
24:50 At about...
24:53 150mm.
24:54 And that'll be twice what the height is.
24:59 So, we end up with kind of 50mm or 75mm or so of height in our pleats.
25:10 But typically for like a big part in a mould.
25:13 We'd do them much taller.
25:14 So, we have kind of 100mm or 150mm tall pleats.
25:19 It really just depends on what you're working with.
25:21 So, we're going to do 8 in this case.
25:26 And we're going to stick them next to the corners.
25:33 I think that's 8.
25:34 2, 4, 6, 8.
25:36 Cool.
25:39 But something else that we need to consider first.
25:41 Is how we are going to have our vacuum line from our vacuum pump here.
25:46 Coming into the part.
25:48 So, there's a few options here.
25:49 I'm going to show you the most kind of accessible approach that doesn't really need any other specialty parts.
25:55 One option, which we're not going to do.
25:58 Is use a little plastic, you know, through bag vacuum port like this.
26:04 And that just needs to sit on the breather to get the airflow from the part.
26:09 And what we'd do is pierce the bag, poke that through.
26:12 And then seal around it with the same sealing tape here.
26:16 The other option, which is really nice and reusable.
26:19 Is a through bag connector.
26:23 So, they are nice.
26:24 I don't have one here to show you unfortunately.
26:27 But it's a nice kind of metal or aluminium through bag connector.
26:31 With a push to kind of quick disconnect port on it for our vacuum line.
26:39 So, those work really good.
26:41 But the alternative is to grab a bit of breather material.
26:46 And a bit of tape.
26:49 I'll just cut a little bit off here.
26:56 And essentially wrap the breather material around the end of the vacuum line here.
27:07 And then tape around that.
27:13 And this line is just going to pass.
27:17 Through the side of the bag.
27:19 Of the seal here.
27:23 And this little port is going to kind of seal at the same time.
27:26 And as long as that passes on to our breather.
27:30 And that's why we kind of have this here.
27:32 To I guess extend that path a little bit.
27:35 We're going to get flow of air into the vacuum port there.
27:38 So, it's just one way to do it.
27:39 That doesn't really need any extra equipment.
27:47 Or consumables I guess.
27:50 We just wanted to do that first.
27:53 Because what I'm going to do is form a pleat over this little part.
27:59 So, I've just torn the tape there.
28:02 And it's not helping that my vacuum line has just been unrolled.
28:08 But we're just going to hold that down in place at the moment.
28:12 Then what I'm going to do is I'm going to pleat over top of that.
28:15 And what I'm going to do is do a pleat each side of our four corners.
28:18 Which is why we have eight of them.
28:20 And what that means is the corners are kind of the areas where we need that extra material generally.
28:26 And that's kind of the typical approach to do it on any sharp corners.
28:30 And what it also means is for a flat part like this.
28:33 As we pull down the vacuum on the bag we'll be able to shift the bagging material flat.
28:38 So, all the excess kind of comes around the side.
28:41 And we don't have any creases on the back of our reinforcement.
28:44 It's really in some cases unnecessary.
28:46 But it also is kind of ideal if we can keep any... Make it all flat on the back of our part.
28:54 We're going to get the best kind of finish.
28:56 No print through of any weird lines onto our surface.
28:59 So, to make a pleat basically just going to fold that in half.
29:04 Come down and then have some kind of little legs at the bottom.
29:11 And we just have a little vertical section there of flat.
29:16 So, that is our first pleat.
29:19 And then what I'm going to do is just make some little tears in our backing paper.
29:33 On our tape around the perimeter here.
29:38 And there are different ways you can do this.
29:42 Depending on kind of what you're working on.
29:45 Or whatever works for you.
29:46 This is just kind of a pretty simple and normal approach to it.
29:57 Didn't tape that very good.
30:04 There we go.
30:05 Cool.
30:06 So, now we grab our lengths for the pleats.
30:12 Again, fold them in half.
30:16 Mostly stick them together.
30:19 And leave two little feet at the bottom there.
30:25 Then come around.
30:28 And we just stick those down to the tape.
30:33 Press them firmly for now.
30:35 Give it a squeeze up the length so it's all nice and sealed.
30:38 But we will come back and kind of do that once the bag is on as well.
30:43 And then we'll just work around.
30:45 Add the rest of these pleats in.
30:48 Trying to work quickly to not drag this on for you guys.
30:56 But also do it right so it all works.
31:08 Like I said these are quite short pleats.
31:12 Because we don't actually need any extra material in this case.
31:16 For just doing a flat part on a flat surface like this.
31:21 But just wanted to kind of illustrate the points.
31:23 Because in most cases what we are making is not completely flat parts.
31:28 And we will need some of these pleats in our vacuum bag.
31:32 And they can also be used in envelope vacuum bags.
31:35 We just make a pleat on one side of the kind of seal.
31:40 And then that gives us some extra bag material.
31:45 Or we can just make a bigger bag is usually the actual approach I guess.
31:51 Cool.
31:51 So, now we have those pleats down.
31:55 Eight of them.
31:57 We are just going to move on to the bagging film here.
32:03 So, what we are going to do is just spread that out.
32:06 And you can see I have probably got too much excess here.
32:09 But it is better to have too much bag rather than not enough.
32:14 Because if you kind of do all this and then get to the end and you are short on the bag.
32:18 You have to try to kind of modify it all as you go.
32:22 And it is just easier to have more bag than you need.
32:25 And then just trim it off at the end or just leave it to be honest.
32:30 So, what we are going to do is start at the corner back here.
32:35 And just going to start laying this down.
32:39 So, I will just fold those two pleats over.
32:43 And we basically work around with a bit of a methodical approach.
32:47 And trying to kind of do it as evenly as possible.
32:51 So, the way to get over the pleats.
32:54 As you will see I just pulled back one side there.
32:56 And then I kind of lay that pleat down.
32:58 So, I have just pulled back one side of the pleat.
33:01 Then I want to kind of pull on the bagging material to keep it straight.
33:07 And then lay it down there.
33:09 And you might be able to see on the camera there.
33:11 But you can kind of see where that has adhered to the sealing tape.
33:16 And there is not an air path through that would cause a leak.
33:21 So, that is one side of the pleat.
33:24 And then we just kind of fold it back the other way.
33:28 And then over the top of the part you want to make sure that tape is held down.
33:34 And I am working right on the edge of the camera view there.
33:37 And then peel off the other side.
33:41 And then lay that down the other side.
33:46 So, we have got this nice kind of continuous seal around there.
33:49 That is really important.
33:50 And you will be able to see already that this is kind of bunching up here.
33:54 And that is essentially how we get our extra bag material.
33:58 Cool.
33:59 So, what I will do now.
34:02 So, pull that next section back.
34:04 And then you just want to keep that bag straight.
34:07 So, you don't get any creases.
34:09 That would result in a leak.
34:12 Come over there.
34:15 And then same thing.
34:17 Pull off one side of our pleat.
34:25 And lay that down.
34:27 Without getting any creases there.
34:32 We will come back through and make sure this is all sealed up after we have the bag down.
34:36 And we kind of roll this over.
34:43 Create our crease or our pleat in the bag.
34:46 Pull back that other side.
34:51 Straighten that out.
34:52 On that side.
34:53 Cool.
34:54 We will get this corner here stuck down too.
35:02 Cool.
35:02 So, now we are up to the same point on each side of the flange.
35:07 And we are just going to work that way.
35:10 Doing this kind of evenly.
35:12 So, we don't get the bag all kind of distorted.
35:15 And end up with some strange bunching going on.
35:20 Again, give a nice press on any of those transitions.
35:24 Where we have those two layers of tape.
35:25 As we go just to kind of make sure they are all sealed.
35:29 Cool.
35:30 So... Do this pleat here next.
35:34 Pull that side back.
35:36 Lay the pleat over down on its side.
35:40 Get that side there done.
35:43 Then I will do this side.
35:58 Stand it up.
36:00 Roll over the top so we don't have an air gap.
36:08 Lay the pleat down.
36:10 And slide down the back side there.
36:13 And then...
36:16 Make sure that is all nice and sealed.
36:19 Same thing on this side.
36:21 And it is pretty kind of rinse and repeat at this point.
36:24 But as we get further on.
36:28 And more of the bag is kind of sealed and stuck into position.
36:32 It gets harder to kind of manipulate the bag into place.
36:36 So, it does get a little bit tricky at some stage.
36:47 I might actually do this side here first.
36:56 Pull that side off.
37:17 And then come back to the other side here.
37:21 Try to straighten the bag up a bit.
37:24 Oop.
37:26 Stuck down a bit.
37:31 Because what I don't want to do is kind of pull this tight at this end.
37:35 And then not have enough material to do that back side.
37:38 So, you want to kind of keep that in mind.
37:40 And come up these flanges straight.
37:46 Because if you have to make adjustments.
37:51 I am definitely a little bit off there.
37:54 And I will pay the price when I get to sealing the top.
37:57 But it will be okay.
38:00 So, no creases up those flanges.
38:03 I will just fold this back a bit here.
38:07 And I will come up this side.
38:18 Same thing here.
38:19 Just coming over this one with the vacuum line through.
38:24 Pull that back.
38:37 I would usually turn this around and go on the other side of the table.
38:42 But it is a little bit tricky with all the cameras set up.
38:49 So, that side.
38:50 And then come down the other side here.
38:54 Pull that plate back.
39:01 Down the edge.
39:02 No creases.
39:09 Same thing here.
39:17 I would have a crease if I continued like that.
39:22 Pull that up.
39:26 The bagging film is pretty tough.
39:30 As you would imagine.
39:31 You don't want it puncturing as it stretches over the pad and everything.
39:36 And that can happen.
39:37 But it is a pretty tough film.
39:40 So, you can kind of force it into place if you need to.
39:45 And I will just pull that off.
39:57 Look up to that corner.
40:02 And same thing here.
40:09 Cool.
40:09 Now, I just have to work along this back edge.
40:12 Which is a little bit tricky without rotating this around.
40:15 Or going around the other side of it.
40:17 So, bear with me.
40:22 I can see that I am going to come up a bit short on the material here.
40:28 But we will be alright.
40:35 Lay that over.
40:46 So, now I am just going to do one at a time.
40:48 Because I will probably have to shorten this other plate.
40:52 Here as I go.
40:55 I might actually just try to shorten them both a little bit.
40:58 So, if I reach in here.
41:02 Nah that one is already stuck on there pretty good.
41:09 Now, what we are going to do.
41:14 Is fold that down.
41:17 To about half the size it was.
41:21 And push that all together.
41:23 Because like I said.
41:25 I got a little bit of the bag kind of.
41:27 This one here.
41:28 I should have pulled this side in a bit more.
41:30 Because I have run short on material at the top here.
41:33 But it is fine.
41:34 We have still got some plates there.
41:36 Oh.
41:37 Just pulled that breather out of place.
41:40 That is all good.
41:41 Still covering all the reinforcement.
42:02 Alright.
42:03 Now.
42:05 We have to try to make this glass plate work here.
42:52 That will take a little bit of work I think.
42:55 But that should be ok.
42:57 Alright.
42:58 Just to tidy things up a little bit here.
43:00 I am just going to.
43:06 Trim all this excess bag I have got here.
43:09 Out of the way.
43:26 Ok.
43:27 So, now we have the vacuum bag.
43:29 With our plate sealed up around the perimeter here.
43:33 A little crease here.
43:34 You can just kind of stretch the bag out.
43:37 And then push it down.
43:38 If you do have any creases.
43:40 It is not the end of the world.
43:43 Stretch the bag and press down.
43:45 Because the bag does have some elasticity to it.
43:50 Um.
43:51 Cool.
43:53 So, what I am going to do.
43:54 Is I am going to start to pull a vacuum.
43:56 For this kind of initial draw down.
43:59 Manipulate the bag into place.
44:00 And I expect I will hear a few leaks.
44:03 And kind of try to seal them up as I go.
44:07 Ok.
44:08 I am not sure.
44:09 You can probably see the vacuum gauge a little bit there.
44:13 Um.
44:15 As we go and just kind of monitor the vacuum.
44:18 So.
44:19 Turn the pump on here.
44:21 Before it gets too tight.
44:23 I am just going to.
44:25 Kind of manipulate it to pull the excess material.
44:30 Into these corners here.
44:33 Um.
44:33 So, we don't have any creases on the back of the actual laminate in the middle.
44:38 Um.
44:40 And if we had done the pleats.
44:42 You know in the middle of each of these.
44:43 That wouldn't be possible.
44:44 So, just something to kind of keep in mind there.
44:47 Oh yeah.
44:48 We have got some leaks.
44:52 I will just have to.
44:54 Kind of work around.
44:55 And find those.
44:57 This is fairly normal.
45:05 So, I am just checking for all of the kind of.
45:10 Joins.
45:12 In.
45:13 The tape.
45:14 Over the pleats.
45:15 Uh.
45:16 And then wear that lapped over on the corner.
45:19 And just give them that.
45:20 A good kind of press down.
45:22 And then squeeze the pleats together as well.
45:26 This one here.
45:27 Is not great.
45:29 But it is what it is.
45:38 Alright.
45:39 Try again.
45:56 You guys probably can't hear that.
45:59 But.
45:59 You can kind of just hear a bit of a hissing sound.
46:06 Slowly fading away.
46:10 So, we have got.
46:11 100% vacuum on our gauge there.
46:14 And I have still got a leak.
46:16 Because it is just slowly dropping away there.
46:19 Um.
46:21 I will keep trying for a little bit.
46:24 But then we will.
46:26 Probably have to.
46:28 Kind of call it quits.
46:30 Just for the sake of the webinar.
46:31 And get into the questions.
46:33 But the general approach here is.
46:36 Obviously.
46:36 Just going to be.
46:38 Working around.
46:40 Trying to find where that leak is coming from.
46:43 And just giving the gum tape a really good press into place.
46:51 Holding the vacuum.
46:52 Pretty good now.
46:58 You can kind of see that.
47:03 Pretty good.
47:04 It is just dropping.
47:07 By about.
47:08 Point wide of a bar.
47:09 Every 10 seconds.
47:10 So, there is definitely still a leak there.
47:12 That you would want to kind of find and fix.
47:17 Before you obviously were comfortable to leave this to cure.
47:21 You know.
47:22 And leave the vacuum switched off.
47:24 That said for a wet lay up cure.
47:27 You don't need to hold it under 100% vacuum or above 90% vacuum really.
47:34 Anything over kind of 40-50% is going to be pretty good.
47:38 And make most of the difference there.
47:40 But for something like a resin infusion.
47:42 This is kind of completely unacceptable where it is at.
47:45 And you would definitely want to be getting that to a better position.
47:51 So, this is essentially what a drop test is.
47:53 Where you pull 100% vacuum.
47:56 Or as close as the pump will get to it.
47:59 And you would leave it for about 30 minutes.
48:01 And just you basically want to see no drop in vacuum there for a resin infusion.
48:06 Pre-preg would kind of follow the same thing there.
48:11 But yeah.
48:12 That is essentially that.
48:14 So, had we done this wet lay out.
48:18 And didn't have any leaks.
48:19 We would now be leaving this to cure for 6 -12 hours.
48:25 Whatever the kind of cure time is of the resin that we are using.
48:28 And then we can come along at the end.
48:31 Disconnect everything.
48:35 And pull the consumables off.
48:38 And the peel ply off.
48:39 And then de-mould the cured part from the mould.
48:44 And hopefully we have got something pretty good.
48:46 And it will probably just need some kind of finishing touches from there.
48:49 Trimming edges and things like that.
48:51 You can see here that I do have this kind of crease.
48:53 Which would be on the edge of the reinforcement here.
48:58 It's probably not going to create too much of a problem.
49:00 In some cases it's completely impossible to do that.
49:04 You know if you have a complex mould with a lot of pleats and things like this.
49:07 You are going to get that.
49:09 If you can avoid it in some cases.
49:11 Especially on aesthetic surfaces.
49:14 It will kind of make a, it can make a bit of a line in the backing surface.
49:20 But not a major anyway.
49:23 Also if you are using your through bag connector or a little vacuum port like this.
49:29 They have got to be on the breather material.
49:32 But I would avoid having them on the back of the surface of the part.
49:35 Because again you are probably just going to end up with.
49:38 A bit of print through.
49:39 Which is basically where you will get a bit of a witness mark.
49:42 Of this on the front of your mould surface to some degree.
49:46 So, things like that that you want to avoid.
49:49 But we will do some more work on this stuff in the future anyway.
49:53 So, doing some resin infusions and showing the different approaches.
49:58 In some other webinars.
50:00 So, I will just jump onto my laptop here.
50:02 See if we have got any questions.
50:04 Before we finish up.
50:07 Okay.
50:13 No questions.
50:14 Cool.
50:15 All good.
50:15 Well we will leave it at that.
50:17 Sorry about those technical difficulties today with the stream.
50:20 But thank you for joining us.
50:22 And we will be back next week with another webinar.
50:26 So, we will see you then.