Contact moulding / Hand lay up
BFG International uses a variety of methods to produce FRP parts. Our experienced engineers will select the best method for your project based on factors such as production volume, parts dimensions, budget, and other requirements.
Our extensive experience with contact moulding enables us to produce innovative and cost effective parts for our customers, including architectural mouldings, boats, and train and automotive parts. The process is best suited for low volume requirements where a one-sided finish is required.
Process
The process is accomplished by first applying a cosmetic surface such as gelcoat to the properly prepared mould. Next, the pattern-cut glass reinforcement is placed in the mould and impregnated with the proper amount of resin. The resin can be applied by brush or paint roller from containers of initiated resin or from a spray gun which combines the resin and catalyst in the precise proportion.
Once the glass reinforcement is fully saturated or “wet out,” the laminate is compacted with specially designed rollers and brushes to remove air bubbles and distribute the resin evenly. Multiple layers, or plies, of laminate are built up in sequence, often with a core material in the middle, to reach the desired thickness. Various inserts, ribs, fasteners, or other items can be incorporated in the moulded part. Following a curing cycle, the part is de-moulded and trimmed as required.
Materials options
Fibres: Any, although heavy aramid fabrics can be hard to wet-out by hand
Cores: Any
Advantages
- There are no size or shape limitations on parts produced using this method.
- The costs of tooling and prototyping are relatively low.
- The process is ideal for low volume parts (less than 1,000 per year).
- Large products, such as roof or wall panels, can even be produced on site.
- The FRP parts can be joined to other materials such as metal, wood, or foam, at the same time.
- Composites can be moulded into complex parts that would require sub-assemblies if done in metal. Reducing the number of parts in a machine or a structure saves time and cuts down on the maintenance needed over the life of the item.
Limitations
- The process is slower and therefore not suitable for the production of large quantities.
- The product quality is not exactly uniform
- Resins need to be low in viscosity to be workable by hand. This generally compromises their mechanical/thermal properties due to the need for high diluent/styrene levels.
Applications
- Best option for prototype development
- Architectural mouldings
- Boats
| General Design Guidelines | |
|---|---|
| Minimum Radius | 6 mm (0.236 in) |
| Minimum Draft | 2 degrees |
| Minimum Thickness | 3 mm (0.125 in) |
| Maximum Thickness | Unlimited |
| Typical Reinforcement Loading | 33% |
| Density (GP resin) | 1578 kg/m3 (.057 lb./in3) |
| Die Lock (Reverse Draft) | Yes |