As far as sand casting is concerned, factories that produce large quantities of precision castings should create conditions to adopt technologically advanced modeling and core-making methods. The production line of the old shock-type or shock-pressure molding machine is not high enough in production, the labor intensity of the workers is large, the noise is large, and it is not suitable for the requirements of mass production, and it should be gradually reformed. For small castings, you can use a horizontal or vertical parting boxless high-pressure molding machine production line, the real molding production is high in efficiency, and the area is small; for middle parts, you can use a variety of boxed high-pressure molding machine production lines, gas Punching molding line to meet the requirements of fast and high-precision molding line Styling and core making.
Single-piece, small-batch production of heavy-duty castings, manual molding is still an important method. Manual molding can adapt to various complex requirements and is relatively flexible, without requiring a lot of process equipment. Water glass sand type, VRH method water glass sand type, organic ester water glass self-hardening sand type, clay dry type, resin self-hardening sand type and cement sand type, etc .; for single-piece heavy castings, the pit molding method is low cost and put into production fast. It is more appropriate to use multi-box molding and split-box molding for mass-produced or long-term shaped products. Although the investment in molds and flasks is high, it can be compensated for saving molding time and improving product quality.
Low-pressure casting, die casting, centrifugal casting and other casting methods are only suitable for mass production because of the high cost of equipment and molds.
Conditional methods should be suitable
For example, it is also used to produce castings such as large machine tool beds. The core forming method is generally adopted, and the core is formed in the pit without making patterns and sand boxes; while other factories use the sand box molding method to make patterns. Different enterprises have different production conditions (including equipment, venues, staff quality, etc.), production habits, and accumulated experience. They should consider what products are suitable and what products are not suitable (or cannot) based on these conditions.
Precision requirements and costs
The accuracy of castings obtained by various casting methods is different, the initial investment and productivity are also inconsistent, and the final economic benefits are also different. Therefore, to achieve more, faster, better, and more economical, all aspects should be taken into consideration. A preliminary cost estimate should be made of the casting method chosen to determine the casting method that is economically efficient and can guarantee the casting requirements.
Although the development of China's foundry industry is in a relatively difficult period, from a long-term perspective, there is still some hope for the development of China's precision casting industry, and market demand has slowly begun to pick up, plus With the development of the strong strength, I believe that China's foundry industry will achieve gratifying results.
Experts said that to fundamentally improve the level of casting technology, the following four points must be achieved: First, the development of simulation technology to improve the accuracy of prediction, strengthen process control, and improve the yield. The problem of regularity is not well grasped, which affects the yield in mass production. Second, the combination of production, education and research. Independent innovation of enterprises In addition to the enhancement of innovation awareness and the improvement of R & D capabilities, it is also necessary to pay attention to and strengthen the combination of "production, learning and research" with precision casting enterprises as the main body. Third, pay attention to material research and development. Materials are the foundation of industry, and there is still much work to be done. In the aerospace field, the research and smelting technology of some new materials such as alloy materials, especially high-temperature alloys, need to be improved, and there is still a large gap with foreign countries. Fourth, pay attention to the improvement of equipment technology. The process is still mainly a problem of equipment. Many key equipment, such as some directional solidification equipment, mainly rely on imports, so the research and development of precision casting equipment remains the focus.