Core Material and Infusion

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#21

Hello,

have you degased your resin? If not the airbubbles can not go ahead and will be enclosed in the soric and durface layer. I always use a flow media, even with soric. The print through can be reduced by a lower vf that can be realized very easy with the MTI hose. But the vf depends on the application.
The airbubbles can also be produced if you have less resin in your part, don’t clamp to early.
Wich vacuum level do you have? Your vac level should be 20 mbar / 0.006in hg absolut
Use flow media and let it end 1" / 2cm before the MTI hose. Place the MTI hose direct to your part and clamp resin feed when the resin reaches the MTI hose.
Soric does work as flow media, but not very good.

#22

Soric is a flow medium, but you need to make sure the resin can enter the Soric. What is a highway worth, if you cannot enter it?

I suggest infusing from the perimeter inwards, use infusion mesh at least 10 cm overlapping with the Soric (that is 4"). Use (plugged) MTI hose in the middle, where the resin front meets.

This will probably cut your infusion time to 25-30% and leave the edges somewhat more resin rich.

#23

I once infused a canoe using soric and a silicone omega feed channel to feed. The feed channel was only about 4mm wide feeding onto the laminate, needless to say it didn’t do too far, well it got half way and just re-infused it.
If you have a square panel and put the feed line (say spiral wrap) diagonally across with a piece of infusion medium under that (about 100mm wide) you will get a good amount of surface area to feed the laminate. Don’t use a perforated film between the infusion medium and the peel ply as this just slows things dramactically. Laying the feed line diagonally gives you the longest feed channel onto the laminate so there’s less laminate to feed as the panel infuses.
There are many ways to do this successfully as you can see, just whatever works for you.

#24

I do engine guards with 20layer kevlar 180gr 5mm soric 2layer glass 200gr 5mm soric and 7layer carbon 200gr, peelply and infusion mesh all acros the laminate. I use 2 paralel feed lines along the laminate and one vac transverse to that. Guards are over 1m2 in size but it gets done in 35min… So i think flow medium over soric is a good thing to do.

#25

Thanks for the help guys, I do appreciate it.

The parts I’m making are bodywork for a racing car so print through isn’t really in issue, just as long as the parts are properly infused.

You can see what I’m making is a strange shape, here’s a finished infusion:

The feed line is around the edge on the left hand side, 6mm Id spiral wrap on top of mesh.

I think I might stick to a similar type of feed/mti hose layout but use infusion mesh more generously.

What do you think to that approach?

#26

What material is the mould made from? I would use flow media over the whole part like I described. Take a bigger resin inlet, inner diameter 8mm, as spiral tube you can use the inner spiral tube from a used MTI hose, that has 8mm inner diameter.
I think Infusion should not take longer than 15 min with flow media.

#27

It’s epoxy topcoat with csm & epoxy backing.

I have some 8mm spiral handy, I will use that next time, maybe tomorrow if I find the time.

I’m thinking about infusing from the outside towards the centre for this part now, using MTI. I think that with a part shaped like this, it’s quite a logical thing to do as it will minimise vacuum drop across the part.

If I’m infusing like that, will I suffer with print through from the vacuum line onto the laminate?

#28

I would use flow media instead of infusing from the perimeter inwards. That often makes problems with the flow front. I never infuse by that way.
Make sure that your mould is 100% tight, your resin degased correct, your vac lever about 20mbar abs, a tight bagging film and the temperature at about 20°C
Then infuse like I told you. It will work. If not I will send you new MTI hose for free.
Pictures from the failed infusion/part will be helpful.

#29

I am surprised DD never infuses from the perimeter inwards. MTI hose is the perfect product for doing that.

About all VARTM parts are produced that way. Infusion time is cut at least in half, without loss of quality.

Print from the MTI hose in the middle of the part is an issue. Try placing it on a strip of hard infusion mesh, this really helps.

#30

Yes, the MTI hose is perfect for that, with a layer of flow media below there is also no print through. Most times you will only habe a print through if you have a low VF. At a high VF >60% the fibres can not be compacted by the MTI hose so that there will be no print.
I think it is a personal preference that I do not infuse from the perimeter. I tested it and it is much faster, but there are some small details I dont like.
If you infuse from the perimeter to the inside the resin the resin meets in an ideal case in the middle where the evacuation medium is placed. The resin flows faster at the top of the laminate so there is always a very small ammount of dry fabrics that is enclosed by resin which has to be saturated by the rest vacuum. This can or will cause very small voids wich you can see in the laminate if you use your laminate as a mirror in the sun.
It does not matter if this part is cut out of the part, but if not I would not do that. Even not at parts where one side is smaller than 1m.
Thats why I infuse from the inside to the outside. And the time only matters if you have to produce a lot of parts.
I would infuse just like he did it, but with flow media. Flow media also degases resin during infusion at the flow front and reduces voids.

#31

So I’ve decided that next time I will infuse from the centre to the outside or the outside to the centre, but I’ve not decided which way round yet.

Below is a picture of a section of the part I was infusing in the image I posted above. You can clearly see the dry spots.

Early on in the infusion I had to stop the resin flow to adjust my resin pot. I did it by clamping the feed line. Could this have caused dry spots too?

To place the fabric in the moulds I’ve been using 3M 77 spray adhesive. I’ve read this is not the best product for this purpose. What else is available to use?

#32

Stopping the resin can be the the reason for the dryspots! If you have a perfect vacuum the resin can degas at the flow front and you will not get the gas out.
If you infuse from the center to the outside use spiral tube for the inlet and place a second layer of flow media below it so you won’t have a print.
And use flow media and perforated release film.

#33

3M 77 indeed is not the best solution, as I have said before, although a lot of people seemingly never had problems.

Get a can of Airtech Airtac 2 (not Econotac) or Aerovac Aerofix 3.

#34

We use many types of cores with infusion, but soric is by far the easiest but take note that it has a "prefered " flow direction along the straight lines being the quickest and slower on the grid lines branching out when deciding on which way you going to lay it in the laminate.

#35

We place a 10cm wide flow meduim on top of our silicone infusion tube to increase the “in” surface area on kayaks so we get v/e resin into moulds quicker avoiding resin stall as it goes off. Depends also on what weave cloth is as we prefer slightly looser weave which also helps flow plus we find it has better resistance to impact delamination especialy with glass onto synthetics.

Without a flow meduim we found resin started to stall at times, also we can gently pull on bag using flow meduim to get resin into certin areas quicker.

Also we if not using a omega shaped silicone tube we dont place spiral infusion tube directly on top of laminate but rap it in flow meduim an an “envalope” in the bag where the flow meduim then goes to the laminate surface. This way there is no tube infusion pressure mark on finished part.

But please dont take this as truth and fact, just the way we do it.

#36

Hello everybody,

my name is Jürgen from western Germany. Im new here to this forum and Id like to share my experiences with the MTI-hose. Since 2003 Ive been spending most of my spare time with the evolution process of my custom motorcycle. One of my ongoing targets is to reduce the weight to the lowest possible point. For that I dug, besides other issues, into the production process of carbon fibre parts. As engineer I always try to raise the bar to achieve the highest possible outcome. But all the parts I´ve produced in the period 2004 until November 2011 were full of defects which required lots of rework. Above all I had problems with pinholes which are not very useful when the parts have to be painted with clear lacquer. Also air bubbles in all kind of sizes often brought me to finish the parts with an additional layer of carbon tissue on top with all the necessary rework. To avoid that, Ive tried various methods, with more or less success. Very frustrating…;-)) Due to the special design of the new parts Ive been working on since December 2010 I decided to delve into the infusion process. I came across the MTI-hose and and carried out experiments with this auxiliary mean. At the end I´m very happy about this decision since it didnt take long to achieve the best results Ive ever reached. In spite of the sharp edge design of the parts, no airbubbles, no pinholes which means no rework. By the use of a special clear-mould coating I could achieve a glossy surface in one step. What Ive learned during this exercise is, that the outcome gets better, the lower the vaccum is (my pump achieves less than 20 mbar). And a tight vaccum bag is also necessary. Unfortunately I was forced to interrupt the production process for a job-related stay in Brasil for 8 weeks. But I`m confident to finish the parts until July 2012…;-))