When infusion goes bad!


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FLD
FLD
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After many years vac-bagging and avoiding infusion I was tempted to try it after some gentle persuasion.  Freakin' awesome!  Not hard and great results.  Yay!

However, I recently made a booboo.  Infusing a 1.2m x 0.2m part; 4x200g with 6x200g in places; peel ply, mesh, bag.  I opened the inlet clamp and it seemed to stick.  A little jiggle and the resin shot through, not all the way but a good chunk was done in about 20 sec.  Bugger!  Let it flow at a more sensible rate to finish up.  I let a little more flow in on completion but as expected its pinhole-tastic on the fast bit.  Is there any contingency for things like this, ie should I have let more resin flow through or is it a once the damage is done thats it?

If there's a fix it would be good to have a list of problems and solutions.
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wozza
wozza
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For me one of the main attractions of infusion is the ability to control and fine tune the process. I always start my infusions off slowly, just opening the clamp enough to allow a steady flow of resin. Once the resin has traveled the entire length of the spiral I begin to open the clamp a little at a time. The flow rate will decrease naturally the further the infusion advances. On smaller parts I may never open the clamp fully.
On laminates that vary in thickness or have strategic areas of reinforcement a slow infusion is necessary to allow these areas time to fully wet through. The resin will always take the path of least resistance and thicker areas can be left starved of resin if the infusion is too fast.  On hard points for example I try and decrease the size of the reinforcement slightly on each subsequent layer. This produces a tapered edge for the resin to feed into rather than suddenly hitting a wall of reinforcement which it will try and go around rather than through. Doubling up on flow mesh in these areas can help also.
Also with a slow infusion if some drier areas appear you can massage these areas to manipulate the resin into the reinforcement. With a fast infusion the resin has reached the outlet before you have even noticed them. 
I don't feel there is any greater chance of air bubbles in the resin being trapped in the laminate in fact I think the opposite is true. Its just with a fast infusion you don't have time to notice the air as much.
Rather than stopping the flow mesh short of the vac outlet I prefer to place a small piece of breather cloth under the vac outlet to act as a resin choke.
Stopping the flow mesh short reduces the air path to the laminate which can lead to air being left in the reinforcement when vac is pulled.
I don't degas but in the colder months I stand the resin pot in a bath of hot water whilst mixing. The heat not only makes dispersion of the hardener easier/quicker but will cause any air to rise to the surface, self degassing if you like.

As with many things individual set up will determine what works best for you. Smile

Warren
  

Carbon Copies Ltd
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