Investment Casting
Production Technique
Investment casting is a manufacturing process in which a wax pattern is coated with a refractory ceramic material. Once the ceramic coating material is dry and hardened, the wax is melted out and leaves an internal cavity the shape of the final product’s geometry. Molten metal is poured into the cavity where the wax pattern was. The metal solidifies within the ceramic cavity, cools, and the ceramic is removed from the metal casting. The result of this process is a net to near-net precision metal component which can be used for a broad range of applications in various industries.
Within the group of investment casting techniques, there are 2 different subcategories: traditional silica sol investment casting and waterglass investment casting. In the traditional silica sol investment casting, the wax is removed from the ceramic cavity by heating in a furnace. In the waterglass case, wax is removed using hot water and often, the wax can be recycled. The silica sol technique is more expensive but allows for a higher dimensional precision.
Technical details:
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The dimensional tolerances for silica sol investment casting are listed in table DCTG 6 (standard ISO 8062-3). For wall thickness, table DCTG 7 should be used. For the waterglass technique, the dimensional tolerances can be found in table DCTG 8 and for the wall tickness, one should use table DCTG 9.
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The weight can vary from 100 grams to weights of approximately 100 kg.
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The surface roughness depends on the technique (silica sol is slightly better than waterglass) and is in general around Ra= 6 μm.
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The minimal wall thickness depends on the design of the part but it is recommended to take at least 4 mm.
Materials
There are many different possibilities in material choice. In most cases, we use this technique for the production of steel and stainless steel parts. Almost all alloys are possible and our material scientists, can advise you on the most suitable material for your application.
