Envelope bagging of multi part moulds
Once a part is made by vacuum infusion in a multi part mould, the preparation of the mould before the next infusion takes a lot of time. The resin runs everywhere around the mould and between the flanges – not only through the reinforcement. In every wrinkle of the bag, the resin hardens to sharp spikes. The complete outside of the mould needs to be sanded before making the next part.

Vacuum Drop Test envelope bagging
My first envelope bagging was catastrophic. The fife following bags have been airtight in the first attempt. But my experience has shown the following:
In the first drop test of a large envelope bag, the bag seems to be leaky. The pressure lowers from -29 in Hg to -25 in Hg in about 30 minutes. After repeating the test two more times, the leak seems to close itself without doing anything. I assume, a big envelope bag encloses some depots of air, which need a lot of time to reach the tube to the pump. After the 3rd test the bag is holding the vacuum.

Strongly divergent infusion times
The first half of the mould (the part from the infusion tube to the flange in the middle of the mould) is infused in about 4 minutes. That is about 50% of the reinforcement. After the Flange, the rest of the mould needs up to 35 minutes more to be fully inflated. I have no idea why. Probably because the resin splits its way and goes through the gap in the flanges and all around the outside of the mould. Perhaps I should use longer spiral tubes…














A fast rough cut
I use a boron carbide cutting disc for the first rough cut to about 3 mm from the edge of the part. I do it inside of my sandblasting chamber with running suction. It works very well if the resin is fully cured.


Regards
Frank

And here the same mould but with longer (1.4 m) Resin Infusion Spiral:



regards
Frank