Casting-precision casting-sand casting-casting related knowledge to explain

1) Wide range of adaptation. The casting method is almost not limited by the size, thickness and shape complexity of the casting. The wall thickness of the casting can reach 0.3~1000mm, the length is from a few millimeters to more than ten meters, and the quality is from a few grams to more than 300t. It is suitable for producing parts with complex shapes, especially complex inner cavities, such as complex boxes, valve bodies, impellers, engine cylinders, propellers, etc.

2) The casting method can use a wide range of materials, and almost all alloy materials that can be melted into liquid can be used for casting. Such as cast steel, cast iron fly all kinds of aluminum alloy, copper alloy, continued alloy, iron alloy and pot alloy castings. For brittle alloy materials with poor plasticity (such as ordinary cast iron, etc.), casting is the only feasible forming process, and iron castings are widely used in industrial production, accounting for more than 70% of the total casting output.

3) The casting has a certain dimensional accuracy. Under normal circumstances, than ordinary forgings, welding parts forming size accurate.

4) low cost, good comprehensive economic performance, energy, material consumption and cost for other metal forming methods.

Castings account for 40% ~ 80% of the total quality in general machines, while the manufacturing cost only accounts for 25% ~ 30% of the total cost of the machine. The reasons for the low cost are: ① Flexible production methods, and mass production can organize mechanized production. ② can make extensive use of waste, old metal materials and renewable resources. Compared with forging, its power consumption is small. ④ There is a certain dimensional accuracy, so that the machining allowance is small, saving processing hours and metal materials. Casting is the main supplier of rough and parts in machinery manufacturing industry, and occupies an extremely important position in the national economy. Castings account for a large proportion of mechanical products. For example, key parts (89 kinds) of internal combustion engines are castings, accounting for 70% ~ 90% of the total mass, and the quality of castings in automobiles accounts for 19% (cars) ~ 23% (trucks); The quality of castings in machine tools, tractors, hydraulic pumps, valves and general machinery accounts for 65% ~ 80%. Castings in agricultural machinery. Quality accounts for 40% to 70% of the heavy, large and difficult equipment in mining and metallurgy (steel, iron, non-ferrous alloys), energy (fire, water, nuclear power, etc.), marine and aerospace industries, and castings account for a large proportion and play an important role.
The method of liquid metal solidification and forming mainly refers to the process of casting and forming. It is the method of first manufacturing a mold cavity with a shape and size corresponding to the required parts, and then filling the liquid metal into the cavity, and obtaining parts (called castings) after cooling and solidification.

There are many methods of solidification forming. According to the different methods of filling the mold with liquid metal, it can be divided into gravity casting (liquid metal filling the cavity by its own gravity), low pressure casting, squeeze casting, and pressure casting (liquid metal filling the cavity under certain pressure). According to the formation of different mold materials, can be divided into a type (such as sand casting, ceramic casting, shell casting) and permanent type (such as metal casting). For sand casting, according to the different sand binder, there are clay sand, resin sand, water glass sand, etc. O according to the different modeling methods, there are manual modeling and mechanical modeling. In addition, for some special solidification forming parts, continuous casting (long casting with equal cross-section), centrifugal casting (cylindrical casting), solid casting, investment casting and other methods can also be used.