Precision Casting Process

- Jun 13, 2017 -

Precision Casting is a general term for obtaining precise castings. Compared to the traditional sand casting process, precision casting castings are more accurate and better surface finish.

Basic concepts of precision casting

Precision Casting includes: investment casting, ceramic mold casting, metal casting, pressure casting, EPC casting.

The more commonly used is the investment casting, also known as Lost wax casting: The selection of suitable melt material (such as paraffin) to make the melting mold; repeated dip in the refractory coating and the blasting process in the molten mold, hardened shell and dry; then melt the inner mold, obtain the cavity, Precision Casting roast the shell to obtain sufficient strength, and burn the remaining melt material, pouring the required metal material, solidification cooling, shelling after cleaning sand, so as to obtain High-precision finished products. According to the needs of the product or heat treatment and cold processing and surface treatment.

Precision Casting Process

Shell drying)---dewaxing (steam dewaxing)---------------mold shell roasting--casting (pouring molten steel in mold shell)------

The process of casting production is basically like this. Precision Casting Generally can be divided into wax, shell, pouring, reprocessing, testing

Wax (wax, wax, tree)

Wax----making wax molds by means of press waxes

Repair Wax----Fix the wax mold

Group Tree------set the wax model into groups

The shell includes (hanging sand, hanging slurry, drying)

Pouring includes (roasting, chemical analysis also known as the spectrum, pouring, Shell, gate, grinding Gate)

After treatment include (sandblasting, shot blasting, correction, pickling)

Inspection includes (wax inspection, initial inspection, inspection, Precision Casting finished product inspection)

Technical Requirements

Precision Casting Method Adaptation

For example, sand casting, a large number of factories should create conditions to adopt advanced technology modeling, core-making methods. Old-fashioned shock-type or shock-compression molding machine production line productivity is not high, the labor intensity of large, noisy, not suitable for a large number of production requirements, should be gradually reformed. For small castings, it is possible to use horizontal or vertical type of high pressure molding machine production line, solid model production efficiency and high, small footprint; for the medium parts can choose a variety of box high-pressure molding machine production line, gas-punching molding line to adapt to the rapid, high-precision molding production line requirements, core-making methods can be selected: Cold Core box, Precision Casting hot core box, shell core and other efficient core method.

The medium batch large scale casting may consider the application resin from the hard sand modelling and the core.

Single-piece small batch production of heavy castings, manual modeling is still an important method, manual modeling can adapt to a variety of complex requirements more flexible, not a lot of process equipment. It can be used water glass sand type, vrh method water glass sand type, organic ester water glass self hard sand type, clay dry type, resin self hard sand type and cement sand type, etc. for the heavy-duty castings with single piece production, the cost of the ground pit modeling method is low and the production is fast. Precision Casting Batch or long-term production of stereotypes products using multiple box modelling, split-box modeling method is more appropriate, although the mold, sand boxes, such as the beginning of high investment, but can save molding hours, improve product quality compensation.

Low-pressure casting, die casting, centrifugal casting and other casting methods, because of equipment and mold prices are expensive, so only for mass production.

The conditional method should be suitable for

For example, the same is the production of large machine tools, such as bed castings, generally used the core molding method, do not make the appearance and sand box, in the ground pits in the core; Different enterprise production conditions (including equipment, site, staff quality, etc.), production habits, Precision Casting accumulated experience are different, should be based on these conditions to consider what products and unsuitable (or not) to do what products.

Precision requirements and costs

The casting precision of different casting methods, the initial investment and productivity are not consistent, the final economic benefits are also different. Therefore, to achieve more, faster, better, province, we should take into account all aspects. A preliminary cost estimate should be carried out to determine the casting method with high economic efficiency and guaranteed casting requirements.

Although the development of foundry industry in our country is in a comparatively difficult period, however, from a long-term perspective, China's precision casting industry development or there is a certain hope that the market demand has slowly begun to pick up, and the development of China's foundry industry has a solid strength, Precision Casting I believe that China's foundry industry will certainly achieve gratifying results.

Experts said that to fundamentally improve the casting technology must do the following four points: first, the development of simulation technology, improve the accuracy of the prediction, strengthen the process control, improve the yield. The regularity of the problem is not well mastered, thus affecting the yield in mass production. Second, the combination of research and production. In addition to the enhancement of innovation consciousness and the promotion of research and development ability, the enterprise's independent innovation needs to attach importance to and strengthen the combination of "production, study 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 much work to be done. In the field of aeronautics and astronautics, the research and smelting technology of some new materials, Precision Casting especially high-temperature alloys, is still to be improved, and the gap between them and abroad is still bigger. Four, pay attention to the upgrading of equipment technology. Technology is mainly the problem of equipment, many key equipment, such as some directional solidification equipment is mainly dependent on imports, so precision casting equipment research and development is still the focus.