Discussion on Investment Casting Technology of Flat Castings

In the production of investment casting, people pay more attention to the castings with complex shapes, and take various measures in the process to obtain qualified castings, but the castings with one or more large planes are mistaken for simple, technologically It is also easy to ignore, and the general investment casting process is often used, resulting in serious casting defects. Practice has proved that for castings with a continuous plane area greater than 5000mm2, if the general investment casting process is used, more than 60% of the castings will be. The plane part is particularly prone to defects such as bulging, rat tail, depression and scarring, which seriously affects the quality of castings and the economic benefits of the enterprise. It must be pointed out here that the so-called “larger plane” is a special application for the investment casting process. In terms of properties, the size of the above area is not a large plane for sand casting, and it is not easy to produce the above casting defects.

Measures to prevent defects:
1 Eliminate congenital factors that produce defects. The part structure should be reviewed for investment casting process, and on the premise of not affecting the use requirements, the part structure should be modified with the design department to avoid large planes appearing on the parts or destroying the continuity of the large planes. Eliminate the congenital factors that produce such defects, and also prevent the generation of defects.
2 For castings that must retain large planes from design considerations. Measures such as setting process ribs, process tables, process holes, and process grooves can be taken. The continuous large plane is decomposed into several small planes, which can be produced according to the general investment casting process (the process ribs, tables, holes, and grooves are generally set on the processing surface, which can be removed during processing)
3 For flat castings that are not suitable for the above two measures (which are a lot in production), according to the above analysis of the causes of defects, combined with practical experience in production, formulate reasonable process specifications for the main influencing processes.

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