Defect analysis of improved lost foam casting turbine exhaust nozzle

The simulation results of lost foam casting of the improved turbine rear exhaust nozzle are shown in the figure. It can be seen from the figure that the insufficient pouring phenomenon originally appeared on the top of the lost foam casting no longer appears due to the increase of risers, and there are no defects such as insufficient pouring, shrinkage and porosity in the lost foam casting itself, and there are only insufficient pouring and shrinkage in the gating system. Since the gating system will be removed in the subsequent processing, it does not belong to the lost foam casting itself and will not affect the use of the exhaust pipe after the turbine, so it is already a qualified lost foam casting for the lost foam casting itself.

The result analysis shows that there are two shrinkage and shrinkage cavity defects on the top of a single lost foam casting. After the process improvement, the defect can be eliminated only by adding a riser near the gating system, which not only saves the material, but also saves the subsequent processing process of removing the riser and avoids the damage to the lost foam casting caused by subsequent machining.