Effects of riser temperature field on shrinkage defects in investment-cast centrifugal wheels

In investment casting process, the temperature of the riser plays a critical role in solidification behavior and shrinkage feeding capacity. Riser temperature inevitably declines owing to multiple processes prior to pouring and heat exchange with the surrounding environment during casting. The centrifugal impeller, a key component of aerospace engines, was studied. A temperature field control method for the riser during casting was proposed, based on a quantitative analysis of pre-pouring temperature variations and their influence on shrinkage defects. By wrapping the riser with insulation cotton and applying riser insulation agent, the pre-pouring temperature loss of the riser is reduced by 76 °C and the solidification time is significantly extended. As a result, the number of shrinkage defects in the casting is reduced from 12 to 2, representing an 83.33% reduction, while the defect volume decreases from 2.55 cm 3 to 0.31 cm 3 , an 87.84% reduction. This method effectively enhances casting quality by minimizing shrinkage defects caused by disturbances in the riser temperature field. It provides a practical solution for temperature field control in investment casting, offering significant technical support for improving production efficiency and product quality.