The principle of choosing casting method

The principle of choosing casting method
Casting is a kind of old manufacturing method, can be traced back to 6000 years ago in our country. With the development of industrial technology, the development of casting technology is also very rapidly, especially in the late 19th century and the 20th century, there are many new casting method, such as low pressure casting, ceramic casting, continuous casting, etc., in the second half of the 20th century was perfected, and practical application. Since today for casting, precision casting, casting quality cost and the improvement of casting automation, etc, casting technology to motors, large-scale, high quality, the direction of automation and clean, for example our country in recent years in the precision casting, continuous casting, special casting technology, automation and foundry casting forming simulation technology has been developing rapidly. Casting processes mainly include: metal melting, model manufacturing, clean casting solidification and stripping, etc. Casting method is commonly used sand mold casting, followed by special casting method, such as: metal mold casting, investment casting, plaster mold casting... And so on. Sand mold and sand mold casting can be divided into clay, and organic binder sand mold, resin self-hardening sand mold, mold and so on. The principle of casting method choice:
1 preferred sand mold casting according to the statistics in all casting production, 60 to 70% of the casting is made of sand mold production, and 70% of them are using clay sand mold production. Mainly because of sand mold casting as compared with other casting method is low cost, simple production process, short production cycle. So like a car engine cylinder block, cylinder head, crankshaft, etc are of clay green sand casting process. When wet can't meet the requirements to consider using clay sand table dry sand, dry sand mold or other mold. Coatings for green sand mold casting can be from a few kilograms to dozens of kilograms of weight, and clay dry production castings can weigh up to dozens of tons. In general, for medium and large casting, iron casting self-hardening sand mold can use resin casting parts can water glass sand mold to produce, size precision, smooth surface castings can be obtained, but the cost is higher. And, of course, the sand casting production casting accuracy, surface finish, material density and microstructure and mechanical properties are often poor, so when casting these performance requirements higher, other casting method should be used, such as casting (lost wax casting, die casting, low pressure casting and so on.
2 casting methods should be appropriate to such as sand casting production batch and mass production in the factories should create conditions for the modeling of advanced technology, core making method. Old jar type or shock squeeze molding machine production line productivity is not high, workers labor intensity big, noise big, does not meet the requirements of mass production and should be modified step by step. For small castings, can use horizontal parting or vertical parting type high pressure molding machine production line, modeling and high production efficiency, covers an area of less; For the thing that can be used in the various cases of high pressure molding machine production lines, air impact molding line, to adapt the demand of fast, high precision molding production line, core making method can be used: cold core box, hot core box, shell core efficient core method, etc. Medium batch of large castings can consider to use resin self-hardening sand molding and core making. Sheet small batch production of heavy castings, manual modeling is still important method, manual able to meet the requirements of various complex is more flexible, does not require a lot of process equipment. Can be used sodium silicate sand, VRH law sodium silicate sand, organic ester sodium silicate self-hardening sand mold, clay self-hardening sand mold and dry type, resin cement sand mold, etc.; For heavy casting piece production, pit modeling method of low cost, fast production. Batch production or production for a long time of finalize the design product box, split box shape modeling method is used to be suitable, although mold, sand box, etc. Start investment is high, but from the compensated save modeling cycle time, improve the quality of its products. Low pressure casting, die casting, centrifugal casting and other casting method, for equipment and tooling is expensive, so only suitable for mass production.
3 modeling method should be suitable for factory conditions such as also is the production of large machine tool lathe bed casting, general assembling modeling method, don't make shape and sand box, core in the pit; While other factories using sand box molding, production. Different enterprise production conditions (including equipment, venue, staff quality, etc.), production habits, experience different, should consider what suits to do based on this product and is not suitable for (or not) to do the product.
4 should take into account the precision casting requirements and the cost of all kinds of casting method for precision castings, investment and productivity are not consistent at the beginning of the final economic efficiency also have differences. Therefore, to do more, faster, better, province, all aspects should give attention to two or more things arrives. Selected for dealing with the casting method carries on the preliminary cost estimates, to determine the economic benefit is high and can ensure that castings foundry method.