The quality of investment casting directly affects the geometry, dimensional accuracy and surface roughness of investment casting impeller. When investment casting impeller blade is an important and high precision product and relatively large parts, the mold material with higher strength and thermal stability and smaller shrinkage must be used to prepare the investment mold, so as to ensure the dimensional accuracy and surface roughness of the investment casting impeller blade. However, due to the large shrinkage and thermal stability, the commonly used mold materials can not meet the requirements of high precision and large precision parts.
| Rosin polymerization | Modified rosin | Paraffin | EVA | Melting point / ℃ | Softening point / ℃ | Tensile strength / MPa | Shrinkage /% |
| 17 | 40 | 30 | 3 | 74-78 | >40 | 54 | 0.4-0.7 |
During the experiment, the formula of the selected rosin based mold was modified. EVA was used to replace polyethylene, paraffin and lignite wax were used to replace Sichuan wax, and polymeric rosin and modified rosin were used to replace rosin to prepare the mold used in the experiment. Its composition and properties are shown in the table.
After testing, the investment casting impeller blade mold material has good comprehensive properties, which is characterized by small shrinkage, high thermal stability, certain toughness and elasticity. The investment mold made of this mold material has smooth surface and small shrinkage, which meets the technical requirements of impeller investment mold.