I am building a “coffin cooler” and it will consist of an outer shell, and inner liner. Between them will be insulation foam. I would love to be able to inject the insulation foam, but I know it’s not a simple process. Does anybody have any links or recommended reading? I am looking to do my homework but can’t find anything relevant. Any advice out there? Thanks so much
I assume you’re talking about a 2 part urethane foam? If so, I can tell you from experience that injecting it can be difficult. That stuff starts to kick after about 45 seconds (temperature dependent). I used a turkey baster to try and fill some voids in a mold, and to add rigidity. It worked somewhat, but that’s partly due to the fact that it was below 60 degrees when I did it, so the foam took about 3-4 minutes to really start to kick.
If you are using this within the more “reasonable” temperature range of 70+degrees F, you really need to pour the foam instead of trying to inject it. It will kick too fast otherwise.
I second that…
if you have an access hole on the bottom, you could mix and pour the foam in. The stuff expands quickly so it has to be poured out of the bucket right after mixing.
Should be pretty straight forward
Pouring is no problem. I’d like to get to the point of injecting eventually but pouring is fine for now.
Yes I am referring to urethane foam.
My concern is primarily that the expansion of the foam does not warp my parts…or worse, blow them out. I am still in the process of creating the plugs for the part. Im not to the point of making the mold yet. My initial idea was to create a set of molds that will allow me to join the two components, while still in the mold…and apply the foam while the parts are still in the mold. I was hoping this would prevent the parts from warping, but now I still need to relieve the pressure somehow, and also not add too much foam. I figured I could join the two parts, then fill them with water to measure the volume. From there I could figure out the correct amount of foam. Then I need to apply the foam evenly so that it expands to fill the gaps evenly.
I already have most of it worked out in my head…but its all guesswork and theory. I would love advice from somebody who has actually done this type of project before.
Below is a picture of a product very similar to what I will be creating. Mine will be smaller.
The urethane foams will make considerable pressure and deform unsupported skin like panels easily.
I used make a surf ski once and these were done while still in the very strong moulds. Then you had to know the exact amount of material to pour in and then we also had chart to follow as this amount also varies depending on the temperature.
We would pour it in through a hole at the high point in the moulds and wait for it to then fill when we would then jamb a foam plug in the hole and hold it there until the pressure resided.
It worked great but could take some tests to work out the right amount.
Thanks! How would I determine how thick to lay up my molds to make them “very strong”?
I would say 10mm is a thick mould but really it all depends on the shapes too.
Shaped sections of your ice box may be fine with just 5-10mm thickness but flat areas can be easily reinforced with PVC foam core “foam sandwich” or other core material like plywood too since it is just a mould. You could also use additional backing structures like plywood on edge glassed on etc. Anything goes really since it does not need to be pretty, just strong.
Thanks for the advice. I will post results