There are various production processes for precision casting equipment. Today, the editor will introduce the water glass shell process, which has a history of 50 years in China and is used by more than 70% of precision casting equipment manufacturers. However, at the same time, this production process has its own shortcomings. Today, the editor will analyze and interpret it for everyone.

The inherent disadvantage of water glass binder is its high Na2O content, and the high-temperature strength and creep resistance of the shell are far inferior to those of silicon solvent shell (only 1/30-1/50 of it). In addition, the refractory material used for the surface layer is quartz sand (powder) with low quality and poor particle size distribution, and the hardener is still limited to using ammonium chloride, so it is inevitable that high-quality precision castings cannot be obtained.

2. The production conditions for the shell are poor, and there is a lack of strict control over the production process and parameters. Due to the strong corrosiveness of hardening agents and the simplicity of dust removal equipment, few workshops have a production environment with constant temperature, humidity, and dust removal. The coating preparation, hardening, air drying, dewaxing and other processes that affect the quality of the shell and castings are rarely strictly controlled according to industry regulations. Regular testing of coating viscosity, smear weight, hardener concentration, pH value, etc. The temperature, humidity, wind speed, and other factors at the air dried area of the shell are not controlled, resulting in mass scrap quality accidents often occurring during high, low, or rainy seasons. In short, most factories remain at the stage of manual workshops, relying on skills rather than scientific quality management for production. This is one of the important reasons for the unstable casting quality, high scrap rate, and high repair rate of water glass shells for decades.

The water glass shell process has the above two problems. In response to these two issues, the Xinhang Precision Casting Equipment editor will provide corresponding solutions for everyone in the next episode. We hope everyone will pay attention to them on time.