Resin Infusion - Materials

[Gareth - UK]

HI - Im currently in the process of doing comparisons between Hand lay up and resin infusion - Im am looking at the potential in weight and cost savings.......

I have a lay up schedule but on 2nd glance at it, it has a large amount of Chopped strand matt in it - Ideally I need a replica lay up schedule that is suitable for the Infusion process. (with woven, uni dir or Bi axials) Can anyone suggest one a good one or know where I can get hold of. In an ideal world be great to have a replica of an actual boat or as close to it as possible....

Also does anyone have any experience with you of contiuous strand matt which is apparently now suitable for resin infusion???

Any help would be greatly appreciated.

cheers

Gareth.

[cristofa]

Gareth

To respond to your question, we need more information - what size is the boat, for example, what is your current layup, and how many boats are you producing?

BTW, I would put the elimination for styrene emissions, and greatly improved working conditions, above 'weight and cost saving' when looking at the advantages of resin infusion - but soon you will have no choice, anyway.

[BTScow]

Gareth,

I did resin infusion for three years on our boats. In that time period we experimented quite a bit with different materials - continuous strand mat - 1.5oz mat - woven and stitched fabrics - combi mat. There is no set formula, I would be happy to share my experiences. With regards to cost/benifit analysis, hand lay up will be less expensive by virtue of there being no consumables (vaccum bag, resin lines etc.) As far as quality, resin infusion is the way to go.

Good Luck -

Crayke

[Splint]

Hi,
It sounds like your trying to find an ideal laminate shedule for your boats but it got me thinking but the questio got me thinking. I was under the impression that when comparing properties between a hand layup and an infused componant of the same core/laminate shedule there should be an expectation of difference as a couple of factors come in to play.

Firstly, the thickness and rigidity of an infused cloth will be less than that of the same cloth in hand layup due to the vacuum drawing off any excess resin, resulting in a more compressed but flexible final product(but also less suseptbile to fracturing).

Secondly, in an application of sandwich core theory, a thinner infused laminate will have a slightly lesser effect than a thicker hand lay up because its' outer surface will be closer to the nuteral axis.

I suspect the differences here would be fairly subtle but in a design where the weight and strength are as low as possible, the use of infusion without reviewing the laminate shedule may be a source of structural problems.

Is anyone able to comment or share experiences on this?

Splint

[BTScow]

Hi Splint,

You are spot on with your first point. But, let me add something if I could. With resin infusion you get a higher glass to resin ratio because you are compressing the reinforcing fabrics in to a smaller area than if you were to hand lay the same schedule. Comparing the two panels - one that was infused and one that was hand layed - the infused panel will be between 15% - 35% thinner than the hand layed panel.

To your second point. Absolutly, as with any laminate schedule, whether hand laid or infused, if it is not carefully reviewed it well let go under load. In fact, at IBEX, I attended a seminar that was all about failed laminates and water ingress into the core. There was one slide in particular that made a very strong case for sticking with woven roving and not going with exotics or infusion. The laminate schedule of the boat was made up of stitched fabric not roving. I don't remember what happened but, the fibers of the stitched fabric let go from stem to stern. The individual strands got pulled back - as if peeling a banana. The argument was this; had roving been used, the overlapping nature of the fabric would have prevented the peeling suffered by the stitched fabric.

Something else with infusion - and why I am such a proponent - is its ability to insure a void - free bond with core. Instead of the lengthy and messy process of bedding core with putty and vibrating rollers, one uses vacuum pressure to pull the resin through the system pushing the air out. This is gross oversimplification - but it works well. Also, that is not to say infusion is not with out its problems.

Hope I didn't ramble,

Crayke

[beturassitsglas]

Do you have any more info on this seminar. I attended IBEX but missed this seminar.

[BTScow]

The seminar was several years ago. But, it was given by Bruce Pfund of Pro-Boatbuilder.

[randbow]

fiberglast.com has plenty of product and info for all kinds of glassing infussion and so on not to mention books and dvds

[rxcomposite]

Originally Posted by Gareth - UK

Also does anyone have any experience with you of contiuous strand matt which is apparently now suitable for resin infusion???

CSM's likes to have a lot of resin content to build up bulk and rigidity. Bulk=rigid. WR's and Uni's is much better when there is very little resin.

It is counterintuitive to resin infuse CSM although CSM counts a lot as a flow medium.

It is a happy combination of both. Tough outer skin of Unis or WR's and bulky inner layer of CSM's. Better still, use foam core.

Rx

[Gareth - UK]

Hi Guys.

many thanks for all of your comments, they have been greatly recieved and taken on board-Just for the case of experimenting and getting the process right I have got a very basic but suitable laminate made up of WR and a 12mm divinycel core..........I built the test panel to a size of 500 x 500 and place the core in at 350 x 350 (restricted in the size I can achieve) The panel has actually come out very well considering its the first time we tried this. Its seems however that underneath the core is a little dry, but the majority of fibres seem to be pretty good.
To insure we get full consildation we are going to increase the diameter of the resin in tube by a few mm keeping the vacuum at the same level.........does anyone have any thoughts on this????