What techniques are there in precision casting?

Let's take sand casting as an example. Factories with large-scale production should create conditions to adopt advanced molding and core-making methods. The production lines of old-fashioned jolt-squeeze or jolt-vibratory molding machines have insufficient productivity, high labor intensity for workers, and high noise. They are not suitable for large-scale production and should be gradually transformed. For small castings, horizontal parting or vertical parting boxless high-pressure molding machine production lines or full-mold molding can be used. The production efficiency is high and the floor space is small. For medium-sized castings, various boxed high-pressure molding machine production lines and air-impact molding lines can be selected to meet the requirements of fast and high-precision molding production lines. For core-making methods, cold box, hot box, shell core and other high-efficiency core-making methods can be selected. For large castings in medium batch production, resin self-hardening sand molding and core-making can be considered.

For heavy castings produced in single-piece and small-batch production, manual modeling is still an important method. Manual modeling can adapt to various complex requirements and is relatively flexible without requiring a lot of process equipment. Water glass sand molds, VRH water glass sand molds, organic ester water glass self-hardening sand molds, clay dry molds, resin self-hardening sand molds and cement sand molds can be used. For single-piece production of heavy castings, the pit molding method has low cost and quick commissioning. For batch production or long-term production of stereotyped products, multi-box molding and split-box molding methods are more suitable. Although the initial investment in molds and sand boxes is high, it can be compensated by saving modeling working hours and improving product quality.

Casting methods such as low-pressure casting, die casting, and centrifugal casting are only suitable for batch production due to the expensive prices of equipment and molds.

Conditions and methods should be suitable.

For example, when producing large machine tool beds and other castings, generally the core assembly molding method is used without making patterns and sand boxes, and cores are assembled in pits. While in other factories, the sand box molding method is used and patterns are made. Different enterprises have different production conditions (including equipment, site, staff quality, etc.), production habits, and accumulated experience. Appropriate products and inappropriate (or impossible) products should be considered according to these conditions.

Precision requirements and costs.

Casting methods obtain different casting precisions, initial investments and productivities are also inconsistent, and the final economic benefits are also different. Therefore, to achieve more, faster, better, and more economical results, all aspects should be taken into account. Preliminary cost estimates should be made for the selected casting method to determine the casting method with high economic benefits and that can ensure casting requirements.

Although China's foundry industry is in a relatively difficult period of development, in the long run, there is still certain hope for the development of China's precision casting industry. Market demand has gradually begun to pick up. Coupled with the strong strength of China's foundry industry development, it is believed that China's foundry industry will definitely achieve gratifying results.

Experts say that to fundamentally improve the level of casting technology, the following four points must be achieved: First, develop simulation technology, improve prediction accuracy, strengthen process control, and increase the yield. The regular problems are not mastered very well, which affects the yield in mass production. Second, combine production, education, and research. In addition to enhancing innovation consciousness and improving R & D capabilities, the independent innovation of enterprises also needs to attach importance to and strengthen the combination of "production, education, and research" with precision casting enterprises as the main body. Third, attach importance to material research and development. Materials are the foundation of industry, and there is still a lot of work to be done at present. In the aerospace field, the research and smelting technology of alloy materials, especially superalloys and some other new materials, still need to be improved, and the gap with foreign countries is still relatively large. Fourth, focus on improving equipment technology. In terms of process, it is mainly equipment problems. Many key equipments, such as some directional solidification equipments, mainly rely on imports. Therefore, the research and development of precision casting equipment is still the focus.