Advantages of Investment Casting

To produce investment castings, it is not only necessary to adopt advanced and reasonable casting processes and equipment, but also to make the part structure itself meet the requirements of casting production. It is also necessary to ensure the quality of investment castings, simplify casting workers, and make the part structure itself adapt to the casting process. This kind of performance that requires and guarantees the quality of the cast parts is called the casting process of the part structure. The main design steps of a qualified cast part include:

① Functional design

② Modify and simplify the design based on casting experience

③ Metallurgical design (melting Selection and applicability of mold casting materials); consider economy.

When analyzing the casting process of the part structure, we must first consider ensuring the quality and use requirements of the investment castings to prevent the one-sided pursuit of simplifying the casting process. If the structural design is found to be unreasonable during the review. Research should be conducted with the design unit and user unit, and modifications should be made while ensuring the use requirements.

The review and analysis of product parts mainly have two aspects: first, to review whether the part structure meets the requirements of the casting process; second, under the established part structure conditions, consider the main defects that may occur during the casting process, and determine whether the part structure meets the requirements of the casting process. Measures should be taken to prevent this in the design.

The casting process plan should be based on the actual production conditions and the production batch size of the investment castings. The parts to be produced by the casting method should be analyzed for the process. After comparing various possible plans, it should be formulated based on the actual and possible conditions.

Whether the structure of the investment casting is reasonable is closely related to the type and performance of the casting alloy, the quality requirements and output of the investment casting, the casting process method and production conditions, etc. In some cases, the economic effects of improving structural craftsmanship can be compared with the effects of rationalization, mechanization, and automation of the production process.

• The viscosity of the surface layer slurry is too small, causing the surface of the casting to be rough. The improvement method is to increase the viscosity of the surface layer slurry.
• The material control time before hanging the sand is too long, resulting in rough surface of the casting. The improvement method is to optimize the material control time and train the operators not to wait for the slurry to gel before hanging sand. If the sand cannot be hung, the surface quality of the casting cannot be guaranteed.
• The surface sand is too coarse, causing the surface of the casting to be rough. The improvement is to use finer sand. Try to use 100-mesh sand for the surface layer. If it is too coarse, it will affect the surface. If it is too fine, the air permeability will be poor.
• When the surface layer is covered with sand, the distance between the sand and the module is too long, causing the sand to penetrate the surface layer, causing the surface of the casting to be rough. The improvement measure is to make the drop of sand as small as possible when hanging sand to reduce the chance of sand penetrating the surface slurry film.

• There are bubbles in the slurry, causing holes on the surface of the mold shell and eventually causing the surface of the casting to be rough. Recommended corrective actions are to replace or reduce the wetting agent or use a defoaming agent (at a minimum). Also adjust the mixing conditions to ensure that no air is incorporated.
• During the slurry preparation or adjustment process, the refractory material is not completely wetted, resulting in rough surface of the casting. The corrective measure is that the slurry must be stirred evenly, and the slurry must be awakened for at least 24 to 48 hours.