The molds used for forming composites, also known as tools, can be made from virtually any material. For parts cured at ambient or low temperature, or for prototyping, where tight control of dimensional accuracy isn’t required, materials such as fiberglass, high-density foams, machinable epoxy “boards” or even clay or wood/plaster models are often suitable. Tooling costs and complexity increase as the part performance requirements and the number of parts to be produced go up. High-rate production tools are generally made of robust metals that can stand up to repeated cycles and maintain good finish and dimensional accuracy.
The molds in which high-performance composite parts are formed can be made from carbon fiber/epoxy, monolithic graphite, castable graphite, ceramics or metals. Each material offers unique capabilities and drawbacks. Sometimes called “hard” tooling, ceramic and metal tooling is relatively heavy and able to withstand many thousands of production cycles. Composite tools, sometimes called “soft” tooling, are more vulnerable to wear and typically find service in low-volume production.