Talk Composites - The Forum for Advanced Composites

Front wing

http://www.talkcomposites.com/Topic33486.aspx

By SHaas - 8/3/2019 4:06:21 PM

Hey everybody,

I want to build a front wing depending on the original part with Prepreg. For sure it has to be a two part mould. My problem is how to get the two parts bonded because the edge line will be only about 1mm and so it is too small to make a bonding. I have some ideas and hope to get some input:

1. after making the two parts I go for a smaller version. I make a second carbon part using the first carbon Part as „mould“. This way I get a smaller part which can be used as connecting part to bond the two main parts together.

2. I lay up the two moulds with a little overlap on one part, put them together, insert a bladder and make a small hole on the downside to inflate the bladder. But actually I have never tried this technique. I get it in theory but I do not now what to use as bladder and how much pressure is necessary.

3. same as number two but using a silicone plug which should expand with heat and produce enough pressure for the Prepreg. In this case I would be happy to get some tips about how to make the silicone plug, especially where to get the right material.

4. last idea: filling each mould with polystyrene foam and use the foam to produce pressure. But I do not know if the foam will produce enough pressure and how to fix the flaps.

So you See, lots of questions :] perhaps some of you understand what I try to do and give me some input.

Have a nice Weekend!
By SHaas - 8/14/2019 9:12:03 AM

 
MarkMK - 8/14/2019 6:53:06 AM
If you've already made both top and bottom parts of the mould, then you could use a narrow strip of sheet wax all the way around the lip of one half of the mould, assuming that there is enough vertical depth to do this? 

If so, the wider the wax strip the better, as this will give you the recessed lip in the part to bond the other half to and a thickness of 1mm should be about right, or as close to the expected part thickness as possible. 

This should work as a 'one-off' solution to getting a joining surface, but it will depend upon the part's depth being sufficient to allow for the joggled edge.


I already thought of something like extending the mould with a lip but I do not yet understand how to use the sheet wax in this context. When I use wax, I will not be able to use prepreg on it.