What are the technical requirements for precision casting
Let’s take sand casting as an example. Factories that mass-produce precision casting should create conditions to adopt technologically advanced modeling and core-making methods. The old-fashioned shock or shock molding machine production line is not high enough in productivity, labor-intensive, and noisy, and cannot meet the requirements of mass production, so it should be gradually transformed. For small castings, a boxless high-pressure molding machine production line with horizontal or vertical parting can be used, which has high production efficiency and small footprint for solid molding; for medium parts, various boxed high-pressure molding machine production lines, gas Punching molding line to meet the requirements of fast and high-precision molding production line, core making methods can be selected: cold core box, hot core box, shell core and other efficient core making methods, and medium-volume large castings can be considered to use resin no-bake sand Shape and core.
For heavy-duty castings produced in small batches, die casting mold is still an important method. Manual molding can adapt to various complex requirements and is more flexible, and does not require a lot of process equipment. It can be applied to water glass sand mold, VRH water glass sand mold, organic ester water glass self-hardening sand mold, clay dry mold, resin self-hardening sand mold and cement sand mold, etc. For heavy castings produced in a single piece, the pit molding method is low in cost and can be put into production. quick. For mass-produced or long-term shaped products, it is more appropriate to use multi-box molding and split-box molding methods. Although the initial investment in molds and sand boxes is high, it can be compensated from the reduction of molding man-hours and the improvement of product quality.
Casting methods such as low pressure casting, die casting and centrifugal casting are only suitable for mass production due to expensive equipment and molds.
Conditional method should be suitable
For example, in the production of castings such as the bed of a large machine tool, the core forming method is generally used, instead of making the pattern and the sand box, the core is assembled in the pit; while other factories use the sand box molding method to make the pattern. Different enterprises have different production conditions (including equipment, site, staff quality, etc.), production habits, and accumulated experience. According to these conditions, it is necessary to consider what products are suitable and what products are not suitable (or cannot).
Accuracy 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, in order to achieve more, faster, better and more economical, all aspects should be taken into account. A preliminary cost estimate should be made for the casting method chosen to determine the most cost-effective casting method that will meet the casting requirements.
Experts said that in order to fundamentally improve the level of casting technology, the following four points must be achieved:
First, develop simulation technology to improve prediction accuracy, strengthen process control, and improve 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 research and development 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, attach importance to material research and development. Materials are the foundation of industry, and there is still a lot of work to be done. In the field of aerospace, the research and smelting technology of alloy materials, especially some new materials such as superalloys, still needs to be improved, and there is still a big gap with foreign countries.
Fourth, pay attention to the improvement of equipment technology. The process is mainly a problem of equipment. Many key equipment, such as some directional solidification equipment, mainly rely on imports. Therefore, the research and development of precision casting equipment and die casting company are still the focus.
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