GB/T 14235.5-1993 is a standard method for the determination of surface Hardness of mold materials in investment casting. In investment casting, the surface Hardness of mold materials affects the casting mass. This standard specifies the equipment required for the determination of surface Hardness for different types of mold materials, such as the selection and calibrating requirements of hardness gauges. Clarify the sample preparation process to ensure that the test samples are representative. Explain the operation details such as loading force, holding time, measurement points and positions during the test process, and also standardize the calculation and representation of results. The standard provides a basis for accurately evaluating the surface Hardness of mold materials, helping to improve the investment casting process Stability and casting quality.