There are many factors affecting the quality of ship inspection castings. One is the design technology of iron castings. During design, in addition to determining the geometric shape and size of iron castings according to working conditions and metal material properties, the rationality of design must also be considered from the perspective of casting alloy and casting process characteristics, that is, obvious size effect, solidification, shrinkage, stress and other problems, to avoid or reduce the occurrence of defects such as composition segregation, deformation, cracking, etc. of iron castings.

Second, there should be a reasonable casting process. That is, according to the structure, weight and size of iron castings, casting alloy characteristics and production conditions, select the appropriate parting surface, molding and core making methods, and reasonably set up the casting ribs, chill, riser and gating system. To ensure that high-quality iron castings are obtained.

Third, the quality of raw materials for casting. The quality of metal furnace charge, refractory, fuel, flux, modifier, casting sand, molding sand binder, coating and other materials is not up to the standard, which will cause defects such as air hole, pinhole, slag inclusion, sand sticking, etc. in the iron castings, affect the appearance and internal quality of the iron castings, and even scrap the iron castings in serious cases. The fourth is process operation. It is necessary to formulate reasonable process operation procedures, improve the technical level of workers, and ensure the correct implementation of process procedures.

During manufacturing, the quality of castings shall be controlled and inspected. First, the process rules and technical conditions for the control and inspection of raw materials, auxiliary materials and each specific product should be formulated. Each process shall be controlled and inspected in strict accordance with the process rules and technical conditions. After that, the quality of finished castings shall be inspected. Reasonable testing methods and appropriate testing personnel shall be provided. Generally, for the appearance quality of professional iron castings, comparison samples can be used to judge the surface roughness of castings; Tiny cracks on the surface can be inspected by coloring method and magnetic particle method.

During casting production, the quality of castings shall be checked and checked. First of all, we should formulate the rules and technical conditions for the control and inspection of processes from raw materials and auxiliary materials to each specific product. Each process shall be strictly controlled, inspected and inspected according to the rules and technical conditions observed by the process. Finally, check the quality of finished castings. Reasonable inspection and measurement methods and appropriate personnel for inspection and measurement shall be provided. Generally, for the appearance quality of castings, the comparison sample can be used to judge the appearance finish of castings; Tiny cracks on the surface can be detected by coloring method and magnetic particle method. For the inner quality of castings, audio, ultrasonic, eddy current, X-ray and γ Ray and other methods to check and judge.