investment casting process(The advantages of the investment casting process are that no parting line is seen, undercut sections are easily formed, no taper is required on the casting, the complexity of shape presents few problems and a very smooth surface and accurate dimensions are obtained. 熔模铸造的优点是没有分型线,铸件凹陷部分易于成形,不需要拔模锥度,浇铸形状复杂的铸件通常也不成问题,所浇铸的铸件表面光滑、尺寸精确。)