Hi Matthieu,
Does it mean you lay everything up, put it 4 minutes in an (normal) oven, at 150°C and you can remove your part after 4min for demoulding? Will there be a difference of finish,strength or chemical resistence?
Good question! - In theory, yes, that's about what it means but this only refers to the Vari-Preg prepregs (so the
200g Vari-Preg and the
400g Vari-Preg), not the Easy-Preg surfacing prepreg. The 5min cure time is taken from the manufacturers cure profile datasheet which does indicate a cure time of around 5 mins at 150'C although having worked with this material for years now (at the higher temperatures) I would say that a cure time of more like 15mins-20mins would be preferable even at this hgih temperature to ensure a full and even cure throughout the laminate. Even still, it's a very fast cure at this temperature.
In terms of demoulding, we would always suggest bringing the mould down closer to room temperature before demoulding the part, this ensures the best surface finish quality. If you demould at 150'C (not to mention the fact that the mould is very hot and difficult to handle safely) it's likely that some print through could occur on the surface. We would wait for the mould to be down at maybe 40 or 50'C before demoulding. In a high volume environment this can be done by forced cooling of the mould if necessary.
The Easy-Preg surfacing prepreg also has a variable cure profile and will cure faster at higher temperatures but for the very best surface finish in an oven-only (out of autoclave) environment we recommend a cure temperature of 90-100'C. Curing at a higher temperature does not allow the resin long enough in its liquid state before cure to flow and settle as well as it does curing at 90-100'C so for this reason, when using Vari-Preg with Easy-Preg (i.e. the way we show in the guide and the way they are designed to be used in the
Prepreg Starter Kit) then certainly start off with a 90-100'C cure for around 8hrs. By all means experiment yourself after that with different cure profiles but we know you'll get great results from a longer 90-100'C cure when working out-of-autoclave.
I see that for the mouldmaking for prepreg you suggest your uni-mould system, but it goes till 90°C, If you'd like to go to that 150°C what should you do? Aluminum mould, Other resin?
Will all the other materials in the kit go till 150°C?
Uni-Mould is happy enough at 90-100'C which is the recommended cure temperature for this system anyway. Providing a Uni-Mould mould has been correctly post-cured prior to use you will have no problems at all at 100'C and so, given the many advantages to the system (namely realistic price and excellent polishability) then we almost always choose to make our prepreg moulds out of Uni-Mould. For higher temperature moulds, aluminium, stainless steel and high temperature epoxies (including prepreg itself) all make suitable mould materials. In all instances,
Easy-Lease Chemical Release Agent will provide a reliable release barrier for the materials mentioned above.
Last question, is there a difference between a throughbag connector and a silicone connector? Because I already have some silicone connectors for resin infusion....
Yes, they're quite different. Rather than me explain here, just take a look at these two product pages (which include a picture and a description). If you've got a
Resin Infusion Silicone Connector then you'll recognise that already. Take a look at the
Through Bag Connector and you'll see it's quite different. The main reason is that no resin will flow through the junction when doing prepreg so the fitting can be much better and more substantial that one that's designed to have resin flow through it (and cure inside it).
Matt StathamEasy Composites / Carbon Mods - Technical Sales