Can I make this? (Carbon/Aramid, PrePreg, Inflatable Bladder, Aluminum Inserts)

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Can I make this? (Carbon/Aramid, PrePreg, Inflatable Bladder, Aluminum Inserts)

Author	Message
morepower	morepower posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 242, Visits: 1.2K	Not the best photos but the way these are made is the same way as you could make your parts. The last two below were test parts and the internal bag was at its maximum so they were not perfect but good enough for the purpose of test fitting.
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Fasta	Fasta posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	I think that a split composite mould will be plenty strong enough with the rough circular shape that it has. Just lay it up thick, 8mm or more thick should do it. Fastacraft Facebook page Edited 11 Years Ago by Fasta
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iso9001	iso9001 posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 26	Vacuum understood. Smart tooling link also interesting. My product requires very specific outside dimensioning, do wrapping a mandrel definitely is out. And I'm very supervised a wrapped bladder will expand at all, seems like the composite thread doesn't have that much stretch to it. I'm liking the idea of a silicon or latex plug undersized to the mold. Lay up both clamshell halves, insert plug, combine and lock down, then bake. Seems very clean and straightforward. Does anyone have a video of this anywhere? Issue: I don't think silicon core is going to work :/ It seems the people using this method are also using very strong molds as the silicon exerts a tremendous amount of pressure on the molds. I saw one reference to aluminum molds (outside of my budget/reach) and even then bolting it together and putting that inside a press! I'm looking at composite/wood/plastic molds, so maybe balloon at least would allow for being able to customize the pressure? Edited 11 Years Ago by iso9001
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Fasta	Fasta posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	To do this with vacuum you need to run a tubular bag though the moulds and also a bag over the outside of the mould too. The bags are taped together at the ends. Fastacraft Facebook page
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emillion45	emillion45 posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 2, Visits: 28	http://smarttooling.com/ Take a look at this.
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iso9001	iso9001 posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 26	Fasta (23/02/2014) Even simpler is to use a solid silicone intensifier or core. So you would need to cast the silicone less the skin thickness in your mould using CSM or sheet wax. Silicone expands a lot with heat and makes good pressure so no need for bags, bladders, pumps or compressors but you will need an oven for pre preg. You may need to form some kind of extension to the silicone so you can grip it to remove. If you wanted you could also cast it with a metal tube down the centre simply to reduce the silicone since it is expensive. Maybe the tube could be withdrawn and then the silicone would also release/remove even easier? I have made small yacht parts like this and it works great. You don't happen to have pics and/or a silicon product link do you? I like the idea of undersizing the silicon. And using wax sheets seems like a good way to get the thickness I want/need. I COULD cut a foam mold for the silicon, but if I don't have to cut two molds, then all the better! Not having to keep positive pressure throughout the baking seems like a plus. But I agree with the idea that I might want to stengthen the mold halves as much as possible. Good thought on the metal tube as well. Someone above wrote on CNC and my budget. I have Free CNC. That is, I do all the CAM and run the CNC router at my work, after 5pm it might as well be mine, unlimited use. To everyone else, I'm actually still not understanding how this could be done with a vacuum...?
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Fasta	Fasta posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	Even simpler is to use a solid silicone intensifier or core. So you would need to cast the silicone less the skin thickness in your mould using CSM or sheet wax. Silicone expands a lot with heat and makes good pressure so no need for bags, bladders, pumps or compressors but you will need an oven for pre preg. You may need to form some kind of extension to the silicone so you can grip it to remove. If you wanted you could also cast it with a metal tube down the centre simply to reduce the silicone since it is expensive. Maybe the tube could be withdrawn and then the silicone would also release/remove even easier? I have made small yacht parts like this and it works great. Fastacraft Facebook page Edited 11 Years Ago by Fasta
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morepower	morepower posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 242, Visits: 1.2K	iso9001 (22/02/2014) I don't want to side track my own thread but... How couldn't this part be made in a vacuum? And what is the difference between evacuation a bag and filling a balloon in terms of constant pressure if I fill the balloon and "tie" it off? You will need a bladder which does not want to burst out of the ends of the moulds. It has to be flexible so therefore it will expand out on every direction. You risk it popping if it is not contained. Using a vacuum there is no risk of the bag bursting unless it is bridging a large area or you make a mistake bagging it... Yes you can hole the bag like any part but you are more likely to get it to work with a vaccum. You can get quite cheap vacuum pumps as mentioned. plus if you use positive pressure and want to run autoclave pressures to get a good result you would need very strong bolts to hold it together and even quite low positive pressure could be quite dramatic if you get a failure. Pre-pregs need heat to cure and adding heat to a bladder will increase pressure anyway. To get an idea how how much air expands even at quite low temp take an empty plastic bottle and fill it with hot water from your domestic tap.. Put the cap back on tightly and see how much it distorts.... With a vacuum you do not have expansion due to heat and the bag seals against itself so there is no risk of a dramatic failure when it heats up... Even polyester resins exotherm so there is always going to be added heat one way or another...
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combustioncraig	combustioncraig posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 26, Visits: 46	It certainly can be made with a bladder mold if it is closed off like morepower said. I think it would be a million times easier to use prepreg and vacuum pump. If you dont want to fork over a lot of money for a vacuum pump. You could use a refrigerator compressor for 20-30 bucks but then again you are talking about cnc parts so I would just pay for a $50 pump (don't know where you are located but here is a link to 3cfm unit). Plus by having a vacuum pump this will allow you to explore rtm and vacuum bagging if you wanted in the future. You will have higher cost of materials per part with prepreg but it will be a lot easier. But there are many ways to skin a cat. Good luck in which ever method you choose.
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iso9001	iso9001 posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 26	I don't want to side track my own thread but... How couldn't this part be made in a vacuum? And what is the difference between evacuation a bag and filling a balloon in terms of constant pressure if I fill the balloon and "tie" it off?
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