Three formulations of plaster based moulding powder have been developed. One is a lightweight foamed product with high permeability, the second is a non-foamed product for higher strength and the third is a product for high melting-point alloys.
- A foamed plaster formulation has been developed which can be used for the casting of low melting point alloys. The moulds are light in weight, which enables to cast bigger pieces and have a high permeability to allow trapped gasses to escape more easily. The setting time of the plaster can be tailored to meet the requirements of the application. Chills can be added to control the freezing of the metal.
Compared to the existing plaster formulations we achieved a reduction of drying time of >50%, which is a huge benefit to the end-users because of energy savings and has a positive effect on the environment.
- A second formulation has been developed which is a non-foamed plaster and this is used for smaller, more detailed moulds, which need to be stronger, particularly when being removed from the pattern. The product is designed for the casting of light alloys.
- The third developed formulation is designed to make moulds which can be used to cast high melting point alloys such as brass or bronze. In this formulation, plaster is used as a binder for refractory materials so that a mould with a high level of detail and smooth surface can be produced but the amount of plaster used is reduced so that the time taken to remove the chemically combined water is minimised and there is less plaster to decompose at high temperatures.
- The fourth formulation is developed to mill a plaster block on a CNC machine, directly from the digital design. This leaves out a few steps compared to the traditional way and leads to shorter lead times and the possibility to show customers of the metal casting companies in due time a prototype.
- All the formulations are designed to have a high level of fluidity so that a high level of detail and surface finish can be achieved.