Composite

A composite is a material which is composed of two physically distinct and mechanically separable phases. One material serves as the fiber while a second serves as the matrix.

Composite Forms and Processing Methods

Manufacturing of composite is an essential factor which should be considered when design composite components. The type of material, the form of material, mold design and processing method are all factors that need to be considered. Below are common forms and processing methods used by teams, but there are various other methods available.

Prepreg

Curing

Ramp

Dwell

Cool down

Dry Weave

Resin Infusion

Resin Infusion, orinfusionis the process of pulling resin through the laminate using vacuum. Infusion requires an inlet to the source of resin, and an outlet to the vacuum pump to exhaust. Depending on the size and complexity, multiple resin sources and exhaust tubes may be required. Like tradition wet lay, a vacuum pump and resin pot are required. Additional consumables are: polyethylene tubing, polyethylene spiral tubing (tubing wrap), flow mesh, peel ply and vacuum bag. It is recommended to use 3/8 or 1/2 ID polyethylene tubing and spiral tubing. The tubing is used for the resin inlet and exhaust port. The flow media is creates channels along the part to allow the resin to flow evenly and adequately. The Peel ply provides a barrier between the flow mesh and the laminate.

While regular lamination resin can be used, specially formulated infusion resins are highly recommended. Infusion resins are have lower viscosity for improved flow, and pot life & gel times designed for the infusion process. In addition to having the proper resin, warming mold surface will aid in the infusion flow.

The laminate is placed into the mold dry. Vertical walls or complex geometry may require adhesive to be used to tack the laminate in place. Super 77, Super 71 or generic adhesive spray are commonly used for this. When the lamination is complete, peel ply is applied over the entirety of the lamination. Flow mesh is then placed in the proper direction; where the diamond patterns are placed going along the intended direction of the resin flow. Failure to draw the resin in the same direction of the flow mesh will inhibit the flow severely. It is good practice to lay the flow mesh approximately 30mm from the all edges except where the inlet and outlet hoses are. This allows the peel ply to act as a resin break which prevents resin from being pulled into unwanted regions in the vacuum bag. For the outlet, leave a 30-50mm space between the outlet tube and flow mesh.

For the resin infusion process the vacuum bag needs to have a perfect seal. Ideally this is done by working the bag and leak testing until the drop the is as close to zero as possible. A part with a leaking bag or a part that is not fully debulked may allow air to introduced in to part. This can cause dryness on the mold surface or other impurities.

Wetlay

Resin is applied, usually by pouring