Wing Test Mould building

Because I had holidays for quite a few days during Christmas, I have been able to work a lot on the wing. Of course, the tooling part of the project is the longest, especially because the wing is cocured. This requires the tooling to incorporate mandrels in different materials to be able to obtain the entire part in one cure cycle. In addition, the mandrels have to be removed without damaging the part.

Since I have no autoclave available, a silicone mandrel will produce the pressure inside the wing structure during the cure. The design and processing of the wing is the same as for a real part, except I cannot use tubular vacuum bags in some cavities due to its size. Therefore, the pressure has to be created inside the cavities so it either has to be a rigid-removable mandrel or expansible mandrel.

Basically, I produced the patterns, composite tooling, silicone mandrel, and some of the foam cores and wooden cores. I used my CNC milling machine to make them all, which is quite a pleasant compared to my other models which had patterns produced by hand.

As I do want to keep it within a reasonable budget, I did not use prepreg. Instead, I used wet layup for all compsite parts, and will try to do the same for the component as well. Here are the pictures of the wet layup process:

 Both patterns have aluminium side plates to create the verticall wall for the composite tooling. A pair of these plates is used joint the composite tooling for the cure cycle.
The plates also have the drilling guidance holes to drill the CFRP inserts on the actual cured part for mounting onto the endplate.

 This is the impregnated fabric with resin. I used a conventional 2x2T 200gsm with EPOLAM 2022 epoxy resin. The cutting templates are defined in Catia according to the layup sequence and ply contourn. A layer of 80 gsm GF is used on the tooling surface to improve surface finishing.

 This is the fabric being laid-up. It handles well, because it is impregnated feels like a prepreg with a very low resin viscosity. This step is performed on both patterns to obtain the top and bottom wing mould surfaces.

 I made an oven from scratch to cure composite parts, which is really handy. It controls the air temperature only but works wonderfully for such small components. Of course, I use vacuum to compact the parts, as you can tell from the picture.

The mould surfaces are then polished to obtain a better cosmetic finishing on the wing surface. The polishing should be made to 1200 grid.