George.+Composite+processes+and+products.

= Composite Processes and Products = = =


 * Composite Process**:

Spray Up - This technique is very similar to Hand Lay up, with the only difference coming from how the Resin and Fibre Glass is applied. As we can see in the video below, it is an open-molding fabrication process, that uses a stream of glass from a chopper gun. The resin and glass may be applied separately but it may also be applied simultaneously. Once this has been sprayed into the mould, workers need to roll out the spray-up to compact the laminate into every part of the mold. This is then cured, cooled and removed from the mold.


 * The Process - Step by Step:**


 * 1) The mold is waxed and polished for easy demolding.
 * 2) The gel coat is applied to the mold surface and allowed to harden before building any other layer.
 * 3) The barrier coat is applied to avoid fiber print through the gel coat surface.
 * 4) The barrier coat is oven cured.
 * 5) Virgin resin is mixed with fillers such as calcium carbonate or aluminum trihydrate and pumped to a holding tank.
 * 6) Resin, catalyst, and chopped fibers are sprayed on the mold surface with the help of a hand-held spraygun. The spraygun is moved in a predetermined pattern to create uniform thickness of the laminate.
 * 7) A roller is used for compaction of sprayed fiber and resin material as well as to create an even and smooth laminate surface. Entrapped air is removed.
 * 8) Where desirable, wood, foam, or honeycomb cores are embedded into the laminate to create a sandwich structure.
 * 9) The laminate is cured in an oven.
 * 10) The part is demolded and sent for finishing work.
 * 11) Quality control personnel inspect the part for dimensional tolerances, structural soundness, and good surface finish quality, and then approve or reject the part, depending on its passing criteria.


 * The Product:**

The Jeanneau Prestige 36 motor yacht is made in exactly the same way. It is made entirely from a fibreglass structure with extra components, such as the seats and electronics, added later on.

> > **The Disadvantages of Making a Boat this Way:** media type="youtube" key="-8kPmVvnfxE" height="405" width="500"
 * The Advantages of Making a Boat this Way:**
 * It is a very economical process for making small to large parts.
 * It utilizes low-cost tooling as well as low-cost material systems.
 * It is suitable for small- to medium-volume parts.
 * It is not suitable for making parts that have high structural requirements.
 * It is difficult to control the fiber volume fraction as well as the thickness. These parameters highly depend on operator skill.
 * Because of its open mold nature, styrene emission is a concern.
 * The process offers a good surface finish on one side and a rough surface finish on the other side.
 * The process is not suitable for parts where dimensional accuracy and process repeatability are prime concerns. The spray-up process does not provide a good surface finish or dimensional control on both or all the sides of the product.

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