I’m new to composites. I mean very new! I’ve been reading everything I can online which has been helpful but in some cases raised more questions than answers. I’m starting a project of replicating a small carbon fiber hood vent (automotive) and I’d like to build a fiberglass mould that can handle all forms of production to include out of autoclave. My main question is what type of gel/tooling coat should I look for that can handle repeated use as well as the heat of an oven? Also, what types of coupling coat (for the fiberglass mould lay up) would be compatible with the gel/tool coat I’d need?
Thanks for any insight you can provide. I apologize for what I’m sure is a simple question but what reading I’ve done has been a bit confusing on this subject.
I plan to make the mould using fiberglass. The part I’m replicating is a polyurethane cast resin replica of a prepreg carbon fiber hood louvre. The original part had some imperfections I fixed with the cast replica. I’d like to make a mould of this to use for making OOA prepreg carbon fiber as well as hand layup fiberglass version copies but I’d also like to be able to use the mould for other production methods if possible (I’d like to learn various methods of replicating this part using this mould as a way to practice). I don’t foresee needing to use heat higher than 250-300 degrees but I’d rather err on the side of caution and make the mould robust enough to handle whatever might be needed. Thanks for responding.
Best would be to make a carbon/epoxy infused tool IMO. CTE of tooling will closely match th part. You can do VE as suggested, however life of the tool will be limited, as CTE is higher, which will likely lead to mould cracking on the surface. If you can find a AOA prepreg with low initial curing (like 122F), you can use the VE tool more effectively, as you can cure low in mould, then post cure free standing after. But generally speaking, if it was me, I would just use carbon/epoxy infused mould as it gives you the most flexibility and cost is not much more. Best of luck
Excellent. Thanks for the reply. Just the information I was looking for. Considering the cost/benefit seems better with with the CF/epoxy choice I think I will go that way. I’m not positive how many parts I will make from this but I know it will be more than a few and is like as much flexibility as possible for future use. I’d rather spend the time making parts than recreating failed moulds. Thanks again everyone!
Making a carbon infused tool seems like huge overkill for something you don’t know how many parts you are going to pull from it. If you’ve got a contract to pull 200 parts then sure, definitely worth it.
But realistically, are you actually going to make that many parts? A well made vinyl ester mould will easily turn out 50+ parts before it starts to deteriorate if you build it strong and use a good semi-permanent release agent.
200 parts? No, very unlikely but up to 50 is possible. Mainly I’d like a single tool that will allow me to practice all types of production methods if possible but it will mainly be used for OOA prepreg use. I’d like to keep the budget for the mould as low as possible but would rather sacrifice cost for durability unless the difference in cost is astronomical. Thanks again for your advice. As I said, I’ve done very basic moulding and casting in the past so most of this is very new to me.
I use vinyl ester moulds all the time with pre preg. Sharp corners at flange edges will often start to break even on the 1st or 2nd use. If the mould has no sharp edges like this then they last much longer but will still need refinishing (polish) and recoat with a release system.
I have plenty of vinyl ester moulds that are then covered with the sticky back PTFE but this only suits simple shapes.
Metal moulds are best by far if you can afford them. They are often not that expensive considering you do not have to do anything as far as mould making compared to the time involved in making composite patterns and moulds only the find they get damaged immediately! Arghhh
i subscribe to the idea that all the flash materials in the world will never make up for poor workmanship. i think that stepping into epoxy/carbon tooling with the potential (as a novice) for questionable workmanship. voids can be hard to spot, even in infused parts(if not 100% ) this will reduce the life of your tool anyway so i suggest a VE glass mould with a decent frame and see haw you go. Once you have a good handle on the basics, by all means get stuck in and get technical. good luck with your project.
Metal moulds are nice, and applicable for sure, but I wouldnt say they’re the best, as CTE is higher than carbon by a lot, especially aluminum. You get in to issues such as growing parts, and being forced to demould hot to prevent crushing/locking. Mass is also very high, making moving, lifting, and storage sometimes not practical. In the end, It all comes down to what you are trying to accomplish. Every type of tooling has its specific application and should be tailored to your part production.
As for carbon tooling to be an overkill, I disagree. Its not expensive for a mould that size, and the results would be superior. Though I do agree that for a novice it will be more challenging, and likely to fail first time or two. Of course doing test panels and learning infusion first would be advisable. As for VE tool, if he wants to be flexible in process, VE tool is limited
Appreciate all the advice folks. I’m definitely a novice and need to take that into account. While I’m extremely particular in my work I still don’t know half of what it takes to make a good end product so I certainly expect to hit more than a few bumps in the road and fail some. Perhaps a VE tool is the best way for me to go after all as it might not be as expensive to fail with those materials as it would others. A cnc machines metal mould would be incredible but would take much of the learning curve of mould making out of the process. Most importantly, I want to learn from this. Maybe I should worry about making a quality mould that can reliably produce a few parts and then if all goes well, build a better mould. Thanks again and please add any recommendations you can. This has all been very helpful.
