According to the invention, the components of the system have been optimised such that they interact and complement each other and such that one cannot operate without the other in the formation of refractory moulds for multiple metal castings in the production of fixed dental prostheses. The invention also relates to a mechanical metal device for positioning increased length refractory cylinders in standard horizontal centrifuges, thereby increasing the number of fixed dental prostheses that can be cast at one time.