How would I infuse this part? (new to infusion)

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#1

A bit of background: I’ve only recently started learning about composites design and manufacturing (for work and hobby). Up until now, I’ve only done epoxy laminating and have been reading about vacuum infusion. I’d really like to switch to vacuum infusion for the parts I’ve been making at home. One of the parts I’ve been using to learn the mold making and layup techniques on is an engine cover for my car. The image below shows a very simplified version of what I’m dealing with. The orange represents my mold surface/flanges. The black represents the part which will be made from CF. The light grey represents two aluminum inserts I have to mold in for mounting purposes.

I don’t really have an issue with getting the materials to lay into the mold properly and I understand the basic principles of vacuum infusion, but with this part, my concern is getting the resin to flow into the upright standoffs around the standoffs.

The bulk (flatter) of the part will be made with a 2x2 5.7oz Twill CF. The vertical cylinders will be formed with braided sleeves. I have planned on only using 5 layers of cloth since it is a cosmetic, non-load bearing component. Another thought was to use 2 layers, some sort of bulking flow media (Lantor Soric?), then two more layers.

Can anyone give me some pointers on how I should go about setting up to do an infusion? My initial thought was to run to feed lines directly on top of the standoffs and two vacuum lines, one on each far end of the part. But again, I’ve never done infusion before and I’m not sure how to set something like this up. Flat sheet, yeah, I think I can manage that but the standoffs are throwing me off.

Thanks.

#2

It’ll come naturally once you do it :slight_smile:
The inserts and standoffs should cause NO problem at all for infusion. Might need to piece together flow media around it, but it’s just another part the resin will flow through. You can get away with just a top layer of flow media, no need to put anything in the middle of the stack.
Make sure you seal the inserts if they are pre-threaded obviously…use clay, tackytape, grease and tape over the top, etc.
As for bagging, just make sure you have enough pleats on all sides to allow the bag to conform around all bends/standoffs.
I would also infuse the short direction, verses going the long way.

#3

How tall are those mounting boss’s? If they arn’t to big I would think you should be able to infuse across like Riff talked about above. That’s what I try to do most of the time. But I do have a mould of beverage holders for the local Baja boaters and I need to infuse those from the middle out. 4" diam. x 5" tall x 4 in a zig zag line. I run one intake tube to the middle of each beverage holder and make a small ring of spiral tube around the base for exhaust. It’s a PIA to setup with disposable threw bag connectors, and every time I do it I wish I could just infuse across. That’s why I say try going across for the first time. Because just like Riff mentioned once you do it, it will come natural to you.

#4

Here’s a picture of a hand laid version I made previously. It took me a while to learn how to get the material to lay properly in the corners, etc. This is probably the 4th part I made and was the first truly quality part I did without anyone else’s help, mold included.

The mounting cylinders are about .75" dia and probably 1.00" tall IIRC. Well, it looks like I need to order some new equipment and materials so I can give this a go!

#5

I think I understand your cup holder one…can you just wiggle a spiral through the middle of the zig-zag stack area, and then vent the 2 sides, with a delay line due to speed of travel UP the stacks?

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like that ish. (spacing is different between writing and the actual post) (vents top and bottom of diagram)

#6

Rotorage, why not feeding resin into the middle of the holders with a hose under the bag? No need for thru bag connectors. Or use the Airtech RIC connectors, these can be reused. You can also inverse your strategy (feed around the perimeter, vacuum in the middle).
I also have designed other, more sturdy connectors (reusable of course, and with a positive seal for the bag) but these are larger than a cupholder.

as for the inserts, these in general pose no problem. You could design a temporary vacuum point on the inserts, only to be used when the need is there.

Also consider the use of Dahltexx, which allows air to escape (always a good vacuum) but does not allow resin to go thru. Great for vacuum points or difficult infusions. Only drawback is that it is not pliable in 3D.

#7

Nice job. I have a simple idea. Allow the aluminum inserts to dowel through the flat mold and allow your resin feed to connect from backside. Draw resin through the aluminum risers into the laminate. This could be a short initial resin feed just to saturate the areas of concern. Then infuse the rest as normal.

The aluminum bosses will act as hole bushings to guide precision drilling from backside. Albieght the bosses will be filled with hard resin but a standard jobber drill will easily clean the boss straight through. A 10 drill and first oversize hole (.1875 drill and .191 machined aluminum boss) would work perfect!

Then freeze and the bosses should fall right out especially if you incorporate and slight taper. The mold would need a slight beef up to be able to handle the release from the mold as the dowels will probably need a bit of encouragement with a rubber mallet.

Just a thought.

#8

dallasb84, that’s a very interesting thought. I never would have come up with that on my own. I think I may give it a try.

#9

One more question. If I do want to do this with a core material and “rolled” edges, how do I set that up in the mold? I ordered some 2mm Aeromat for the core and will be using 2 layers of 5.6oz fabric on top and bottom for the main body. The standoffs will be several layers (6-8) without core of a braided sleeve.

Do I run flow media up to and slightly overlapping the edge of the part from the resin inlet (with a bit going to and around the standoffs), then let the Aeromat take over, or should I plan on covering the entire part with with the external flow media?