Manufacturing sacrificial patterns for casting by salt powder lamination

The increasing use of rapid prototyping (RP) which fabricates complicated models easily, has highlighted the desire for making metal models also with RP technology. However, direct RP technology for metal models is not established yet. This paper presents a technology for manufacturing sacrificial patterns using salt powder. By soaking in water the salt patterns can be removed from moulds very easily. They are converted to metal models very easily through investment casting. The feasibility of the method was examined by laminating salt powder with 3D printing method. In the preliminary test it turned out that pure salt powder is unsatisfactory. So flour was mixed with salt powder for the absorption of the binder, because it is insoluble in water and readily available at low cost. Controlling the mixing ratio tests were made to examine the quality of the salt patterns, and showed promising results not only as sacrificial patterns but also as conventional 3D models. Then metallic models with complicated shapes were fabricated by casting in plaster using these salt models as patterns, and it was proven that these salt models can be used in investment casting as sacrificial patterns.