An autoclave is a device that uses steam under pressure to sterilise instruments, glass, certain plastics and cloths. Processing in the autoclave uses both pressure, vacuum and temperature. This technique is fairly expensive as the investment of the autoclave is quite high. The autoclave is also used when making moulded parts. Here, prepregs (pre-impregnated fibres) are placed dry in the negative mould and then heated at a temperature of 120 °C to 200 °C using bottom and top pressure, depending on the moulded part to be made.