I am starting to plan my curing oven build and want to be able to build enough into it for future growth. Lacking experience I am looking to see what I need in terms of temperature (maximum), ramp rate, vacuum fitting etc. that the collective group can suggest.
Depends totally on the products you are going to make.
But without that knowlegde, I would say a 100’ x 40’ x 20’ oven would do, so you can cook the largest structures.
Ramp rate should be at least 100F / minute, maximum temperature in the 700’s.
:):):)
But perhaps your intended products could get away with something smaller / simpler…
I am a bit space limited as well as budget 
Parts will be CFRP bicycle and motorcycle structural components, mostly one off prototypes. Don’t need to think much about batching, just the processing. I can build a low temp oven such as the foil lines eps ones or I can build something a little more permanent which can yield higher temperatures for higher post cures. I just don’t know if, or how much is needed.
God herman, I hope you meant 1f a min, not 100f!!!
Rob, for those parts, choose your largest size part, and give it a bunch of inches on each side. Maybe give it a standoff rack inside, so higher than you need as well.
Depends on your resin as well. I don’t know much about foam, but you can make a box out of steel or aluminum, mount the heating elements on that, insulate with fiberglass, or other high temp insulation (remember, the heater element itself will get MUCH hotter than what you really want), add a box on the outside, and boom. Oven. You can use a normal thermostat, or use a simple PID with thermocouple. I would suggest adding a fan (really, metal blades long shaft through the box…motor on outside) will help with airflow!!! Don’t want it hot on the top, cool on the bottom.
You can always add a hot air blower into the box, and control that with the PID. 5 degree F per min is a normal ramp rate. Some call for as low as 2f/min. Max temp all depends on your resin again, so your oven materials will be based off that. Prepregs and high TG resins sometimes call for 350f cure, and up to 450f post cure (rare, like CE resin)
For plumbing for VARTM, they have teflon hoses and metal fittings, along with nylon spiral wrap. THICK WALL TUBING is a must. thinwall, will still collapse well below rated temp. For prepreg, you can get a high temp QC fitting and hoses from Airtech/Bondline/et al. Hell, in a pinch, teflon tube, or even copper tubing will work as long as you have a good feedtrhough. You can have a hole for the hoses, or make a manifold on the inside. Up to you, and the size of the oven. Don’t forget thermocouple feedthroughs as well.
Thanks, Riff.
I had originally thought about building a simple Foil lined EPS curing oven and I see some people using them to produce some decent parts. I have read up on some of the higher temp tooling resins and they seem to have a higher post cure temp than I can achieve with the EPS foam route. SO my plan was to build a metal framed, sheet metal oven with a PID controller so I can set ramp and soak cycles and run it mostly unattended. I will run a set of manifolds for both vaccum and pressure and install rails for racks on the inside. Everything I have read looks like the ram rates are fairly slow (1-5 degrees per minute for most epoxy systems) so it does not look like I need a lot of heating elements to ramp up the heat quickly. I wasn’t sure about fans, but may add them just to be safe.
Thanks
I’ve had these two links saved in the fav. for awhile so I can’t tell what user originally posted them. They were from another home built oven thread a year or so ago.
http://www.powdercoatoven.4t.com/construction%20page.html
http://www.tedsfabrication.com/powder_coating_ovens.htm
I was serious on the 100f per minute, and also on the 100ft oven…
EPS is a bit tricky, as it disappears at some 90 degrees C (sorry, still having trouble calculating in F)
There is a nice product simply called “sandwich panel” which is a rockwool sheet, sandwiched in metal sheet, slightly corrugated. Much used for large cooling boxed and the like.
We bought a batch of these in “the wrong colour”. There are a lot of nifty accessoiries, like corner pieces, doors, etc.
Size: as small as possible, but your largest part should fit in. A cheap heater could be a sauna-oven. They usually can be bought cheap second hand. A fan indeed is a must. Either source a high temp one, or route the axle outside.
100ft is fine, gotta fit an airplane body in it. 100/min would vaporize the resin
Rob, keep in mind the end use temperature of your part. ie: will it be right next to a hot engine or frame? If so get some temperatures with a thermometer before choosing a resin and cure cycle/temp. You wouldn’t want to post cure at 200F and come to find out you needed the part to withstand 350F.
Well that is the biggest issue. Some of the parts will need high temp resins which will require a high temp cure. That has been the biggest driving factor away from the foam based 'home built ovens". What I basically was trying to nail down was an envelope of what I should build to.
I/m sure you can find a good and cheap non-foam insulative material. Mostly fiberglass style.
The advantage to the foam ovens was the free standing nature since it was rigid, once that option is gone (or I eliminated it) and I had to build an enclosure that opened up the options. Rock wool insulation is available at my lockat Lowes for $40 for 6, 2"X2’X4’ bats which gets me R-30 and something like 2000F. Steel framing studs and sheet metal will form the enclosure and should be plenty strong once unitized.
For simplicity it is these you are after:
That is what we used.
i have a furnace unit and control panel that came off a bake oven that was 10’w X 8’h X 40"l i would be interested in selling it for 1500$ if you want to drive up here to Ontario to get it
thanks
Beaudacious
Pics specs other info might be helpful. Post the stuff in the for sale forum.