Hi everyone,

Every process has its advantages, or else nobody would use an autoclave.

Strength of the part is not the only criteria for a composite part. Autoclave advantages also include much higher HDT than what we, garage guys, could do, at least for parts that wont fit in our kitchen oven if you see what I mean . And even if it fits, try to monitor it precisely...

Also, DEPENDING THE APPLICATION, you could release several parts during one day with one mould while we DIY'ers can only hope that our fast catalyst will give us the time to demold the part (that we off course infused before going to work, which involves waking up at 4am) and then start waxing the mold again before its midnight so we can sleep a bit before going to work... And I know you all know what I mean...

So if big companies have one autoclave and several exact same molds, it's their benefit to use it, would it be for speed / parts volume or HDT.

Are those parts stronger? Some show studies that say no, some show studies that say yeah. Over qualified aerospace engineers cant live without an autoclave, some guys make their carbon airplane with their molds under vacuum and a simple oven... and it damn looks awesome and professional.

Some parts wont need 250PSI and 250°C, some might. Some resellers sell the same bonnet for a car at 1500 for infusion method and 2500 for the same bonnet made with prepreg/autoclave. Is it worth the 1000 more? If you crash at even 60 Mph, I doubt it could make a difference. Maybe the prepreg/autoclave one shaves 700 grs more? Well, why not but we dont have formula ones.

So, isn't it about getting the last little bit of advantage of each method, for a particular part, simply?

 



 


    A $1000 electronic device will always protect a 10 cents fuse

http://www.gmtcomposites.com/why/autoclave

In a nutshell, these guys tested against autoclave. they say 3% stronger for autoclave but less sheer force. In thier study they explain becasue of the part thickness it was even worse for there boat haul application.

 



If Brute Force Isn''''t working your not using enough...

I dont know where youve guessed these figures from but there completey inacurate? The vacum ovens we have at work run upto 250c and will pull around a steady 250psi of vac. IDEAL for non structural parts (interior trim, small bracketry, robotics cover panels etc).

With regards to being faked, correct the overal performance strength wise cant be matched, but the visual effect is easily faked.

I would Reeeeeeeally like to know just how much stronger... Sure the numbers are there on the pressure in the oven, but HOW MUCH STRONGER EXACTLY is the part?????

 When I see things like "ALWAYS BE SUPERIOR" Id like to know your experience in this and the data in your testing?

Or are you just guessing? I'm not doubting it will be stronger but by how much 2 % or like 50%?



If Brute Force Isn''''t working your not using enough...

for 99% of diy and small business automotive use, an autoclave versus oven curing with something like easypreg, you will have no practical difference in performance for the kind of parts you are producing.

With small parts, from a business perspective, using pre-pregs is a considerable cost saver in time far more than the extra cost of the pre-preg.  Also smaller the part, the harder it is to infuse generally. The time spent getting it perfectly into corners of a small part and bagging it properly are far more costly than the simpler laying of sticky pre-preg.

^^

Errrrrrr, how is a curing oven running at 80 C with 30psi bag pressure the same as an autoclave running at 150 C and 2000psi vessel pressure?!?!?!
Its NOT! And that's the very reason the purchase/running costs of an autoclave are so high and in turn is the very reason that the parts will ALWAYS BE SUPERIOR.

If anything I would say that putting prepreg in a composites oven is a false economy because your simply not getting the full potential of the materials, although I can see it as a very clean and pro way to work and for this reason some people would prefer to use it even without access to a clave...

But if I took a punt I would also say that a bagged prepreg in an oven VS a good infusion in the same oven at the same temp/time would produce a similar result... Its the autoclave conditions that produce a specific end product that YOU CAN NOT FAKE or reproduce any other way...

Kev.

Prepreg is BY FAR the best & easiest way to get incredibly high qaulity (visual & strength!) parts. But also dont discount prepreg vac oven cured NOT clave cured. Same principal as a clave but without the £80++p/hour running cost & £100k+ purchase & installation fee of decent usable size clave. (15ft length for example).

^

In my opinion pre preg should be avoided at all costs and looks like poo poo. I'd use it to make large parts, like a plane wing, that's about it.