Casting Sand - Sand Cast
Binding Foundry Sand
Isocyanate-cured foundry resins
MDI is used in the 'cold process, which produces accurate sand castings without heating, saving energy, time & capital compared to the urea-formaldehyde & phenol-formaldehyde resins. In the 'cold process', a phenolic resin and Polymeric MDI are mixed with sand. The mixture is poured into a mould in an enclosed box. A rapid-curing reaction is then initiated by the introduction of a volatile amine catalyst carried in a stream of air or carbon dioxide. The ratio of binder to sand is 1-2% by weight.