Hello friends,

I intend to make a medium-sized piece (1.35mx 0.30m) with polyester resin, but I saw that it corrodes the potential risk of shrinkage during resin curing.

- The resin has the gel time of: 30 minutes and the manufacturing process would be by Hand Layup + vacuum bag or Resin nfusion.

The doubts are as follows:

"What do I have to do to stop this from slowing down?"
Because I can not have dimensional changes due to the product accessories.

Desmoulding after 4 hours of lamination cause me problems?

We have a small production line and we need to be quick in our process.

Thanks,
Dezer

You are talking about a much longer time frame than I am. I am talking about keeping shrinkage at its minimum, which means controlling the exotherm. As you said, there is always going to be a degree of shrinkage in the solid state, but this occurs over a period of weeks after the initial cure. I am talking about letting the resin cure to a tack-free stage so that the exotherm stays controllable and doesn't cause higher shrinkage than would otherwise be experienced. Once the first two or three layers have gone hard and the heat has subsided, you can do the next few layers. This is generally a case of two or three hours and will have no affect on the degree of shrinkage in the solid state over the next few weeks.

If the components in question are only going to be two or three mm's thick, then there's obviously no need to do this in stages. It's just if the parts need to be five or more mm's thick that doing it all in one hit would certainly result in big exotherms and higher shrinkage.