Wednesday, December 1, 2010

More on the New Door

We have just opened the bag and poured the resin in.  We used about 1200 g of resin to make this part.  We could get away using a bit less next time maybe 1000g.  Of this amount not all ends up in the finished part as you need a bit extra to chase some air out of the part.  There is also some soaked up by the peel ply which gets pulled off the part after its hard.  The peel ply leaves a smooth surface and gets rid of bag lines.  Bag lines are those folds or wrinkles in the bag from getting it to conform to the shape of the part.  There also has to be extra to wet out past the  trim edge of the part.

Here we are part way through wetting the part out.  You can see the puddle of resin near the wetout line waiting for the vacuum to draw the resin into the dry fabric.  We use a Teflon squeegee to manipulate the resin by working on top of the bag.  The white plastic part in the bottom of the picture is the squeegee.  It has helped make thousands of parts. 
The bagged part completely wet out.  We now leave the part under vacuum until it has hardened.  The primary advantage of making parts this way is that the process is fairly clean and you are not in contact with the resin other than mixing it up and pouring in under the bag.  You can take your time positioning the material as there is not imposed time limit of the resin hardening on you.  The technical advantage is that the fiber content of the parts is much better than when doing a hand layup.  We get a fiber content of about 60-65% while with a well done hand layup you are about 45-50%.  The high fiber content gets you tougher parts at less weight.  The negative is that it sometimes takes longer to make the part and it costs more due the extra materials involved.

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