During the early years of the production of foam, simple mixing and grinding equipment were used, with little success. One of the key steps in the commercialization of these foam systems was the development of suitable machinery for continuous production of foam, and they have since been used throughout the globe as the standard production machinery for slab foam. Although the mechanical designs of these foam making equipment are rapidly being improved and many different types of foam machines have now been built, they all work with the same basic processes. The foam components are metered precisely to a mixing head, after that they are efficiently blended and dispersed into molds or onto a conveyor belt. Plastic foam machines are divided into two types of systems: continuous or on-off, where the former is employed for stock production and the latter is for molding. The foam production units usually consist of storage tanks, pumps, mixing head, heat exchangers, pump drive systems, and conveyors to control the flow of foam components