RTM "Like" Process - Need advice

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RTM "Like" Process - Need advice

Author	Message
vasospaz	v vasospaz posted 6 Years Ago Topic Details
v Group: Forum Members Posts: 3, Visits: 22	I am trying to perfect an RTM like process to create a foam core part. My piece is about 4 feet by 2 feet by 1 inch in size. I have a mold for the A side which has a ew compound curves and I am using plexiglass as the B side since the part is flat. My typical layup is a layer of 4 oz and a layer of 6 oz. I am really ting to dial in a process that eliminates the need for mesh and peel ply. I have tried a few runs using resin research infusion resin with medium length hardener 20 - 40 minutes). My problem is that it seems to take too long for the resin to infuse. Are there any tricks to encouraging a faster infusion rate? I'm getting a 65% infusion off the part. I can get a slower hardener but what other options are there? Does the layup schedule matter? Do extra layers help the infusion? I was thinking about inserting a layer of 2 oz polypropylene between or beneath the glass layers. I don't what to use soric. Would this work like an infusion mesh? Can I cut grooves in the foam surface without affecting the finished surface? would this help distribute the resin faster? How do I optimize the location of my vacuum and infusion ports relative to my mold? Any advice would be much appreciated.
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Tescosfinest	T Tescosfinest posted 6 Years Ago Post Details
T Group: Forum Members Posts: 1, Visits: 12	+x vasospaz - 7/8/2018 9:56:02 PM I am trying to perfect an RTM like process to create a foam core part. My piece is about 4 feet by 2 feet by 1 inch in size. I have a mold for the A side which has a ew compound curves and I am using plexiglass as the B side since the part is flat. My typical layup is a layer of 4 oz and a layer of 6 oz. I am really ting to dial in a process that eliminates the need for mesh and peel ply. I have tried a few runs using resin research infusion resin with medium length hardener 20 - 40 minutes). My problem is that it seems to take too long for the resin to infuse. If you are trying to eliminate the need for flow mesh and peel ply, your infusion flow rate will become very dependant on the permeability of the materials you have selected. I don't know what fabric you are using, but generally the fabric in infusions are not that permeable (hence your post) This also applies to the resin you have selected. Yes you can use a longer curing hardener (which is one option) but you are also not changing the viscosity of the resin. Depending on the resin, for epoxies you can heat up the resin which lowers the viscosity but obviously you must check the technical data sheet from the supplier first! +x[quote] vasospaz - 7/8/2018 9:56:02 PM Are there any tricks to encouraging a faster infusion rate? I'm getting a 65% infusion off the part. I can get a slower hardener but what other options are there? Does the layup schedule matter? Do extra layers help the infusion? I was thinking about inserting a layer of 2 oz polypropylene between or beneath the glass layers. I don't what to use soric. Would this work like an infusion mesh? Can I cut grooves in the foam surface without affecting the finished surface? would this help distribute the resin faster? How do I optimize the location of my vacuum and infusion ports relative to my mold? I would agree with using a slower curing hardener as a first option. another option is to heat up the resin to lower the viscosity, but be warned this also has a trade off in reducing the cure time and poses an exotherm risk if carried out improperly. The layup of the panel does matter. The resin will want to take the path of least resistance. Adding more layers should not make any difference if you are infusing across the panel. But it will take longer for the resin to go through the thickness of your part. Adding to this, fibre orientation also has an impact on infusion times. I'm not familiar with the polyproplylene so I cant answer that. But I think the principle is sound. If you can use a different more "open" fabric if should also help. Cutting grooves into your foam would help cutting your infusion time. If the grooves are small enough and the ply stack is thick enough you may get away with it, but it will have an impact mechanically. I don't know how you have been infusing so far, I'm guessing from one side of the tool to other? If this is the case then there isn't much you can do in terms of inlet and vents. The general rule of thumb is to keep your vent the furthest part point away from your inlet (assuming your laminate has even thickness) If you are open to modifying your flexiglass B surface to have the vent in the centre and peripherally fill your part that will help with fill time but leave mark off in the centre of your part. I'm not sure how much help this will be to you, but it sounds interesting.
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vasospaz	v vasospaz posted 6 Years Ago Post Details
v Group: Forum Members Posts: 3, Visits: 22	These comments are very helpful! I got a slower gardener and the intrinsic viscosity of the resin I am using is quite low natively so that’s good. I also got the air conditioning in my shop fixed so now it’s back to a cool ambient temp. My last test made it about 85% of the way. I’m trying to just wet the ply stack but not saturate the foam core. I’m using a 3 lb density foam and I have cut the part open and there is no appreciable infiltration ofvthe foam so that is also good. I haven’t tried cutting grooves yet but that and an infusion test of the wide weave polypropylene cloth will be next. My current stack is a single ply of 6 oz glass and single ply of 4 oz ply even thickness. The polypro will add some bulk and flexibility modulus. I want to avoid putting a port in the center of my B side but I had thought of that. . Your advice about the ports is really helpful. I’ll let you know how it goes Cheers
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oekmont	oekmont posted 6 Years Ago Post Details
Group: Forum Members Posts: 550, Visits: 27K	Maybe something like soric lrc or 3d pet core might solve your problem.
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