Precision Casting With Precision Molding Method To Obtain Accurate Casting Process

Precision casting is the use of sophisticated modeling methods to obtain accurate casting process in general. Including: investment casting, ceramic casting, metal casting, pressure casting, Lost Foam Casting.

Which is more commonly used is the investment casting, also known as lost wax casting: the use of suitable melt-casting materials (such as paraffin) to build the mold; in the mold on the repeated wear refractory coating and sand-resistant sand, hardening shell and dry; And then the internal melting of the melt melted out to obtain the cavity; roasted shell to obtain sufficient strength, and burn the residual melting material, casting the required metal materials; solidification cooling, shelling after the sand, to obtain High-precision finished products. According to product needs or heat treatment and cold processing and surface treatment.

Precision casting, also known as lost wax casting, its products are sophisticated, complex, close to the final shape of the parts, can be processed or rarely processed directly on the use of investment casting is a nearly net shape of the advanced process.

China ancient: Prince Wu Ding, copper ban, bronze lions, etc., are investment casting masterpiece. Since the 20th century, 40 years of investment casting for industrial production, half a century has been developed at a faster rate. Especially in Europe and the United States to develop rapidly. The investment casting is used in all sectors of the aviation, weapons sector, and is used in almost all industrial sectors, especially in electronics, petroleum, chemical, energy, transportation, light industry, textile, pharmaceutical, medical equipment, pumps and valves. In recent years, China has developed rapidly.

The development of investment casting technology makes the investment casting not only produce small castings, but also can produce larger castings. The largest size of castings is nearly 2m, while the minimum wall thickness is less than 2mm. At the same time the investment casting is also more sophisticated, in addition to linear tolerances, the parts can achieve high geometric tolerances. The surface roughness of the investment casting is also getting smaller and higher, reaching Ra0.4μm.


Ceramic casting

A casting method for casting castings made of ceramic slurry. Ceramic slurry from the ethyl silicate hydrolyzate and texture is relatively pure, high thermal stability of fine refractory sand such as fused silica, zircon, corundum and other mixed. In order to make the ceramic slurry in a short time gel, often add calcium hydroxide or magnesium oxide as a catalyst. As the use of refractory ingredients and their appearance are similar with the ceramic, so called ceramic type. Ceramic casting is a new process developed on the basis of ordinary sand casting. Ceramic type has two types: ① ceramic type by the ceramic slurry from the water. The production process is the first fixed on the model board, coat sand box, and then tune the ceramic slurry into the sand box, to be knitted after the mold from the mold, the high temperature roasting that is a mold. ② the use of bushings, between the bushing and the shape of the gap between the ceramic slurry casting mold. Bushing can be used sand type, can also be used metal type. Bushing the ceramic shell with bushing can save a lot of ceramic slurry, the application of more in the production. Ceramic-type castings surface roughness up to a10 ~ 1.25 microns, dimensional accuracy of up to 3 to 5, to achieve the purpose of less cutting. Ceramic casting production cycle is short, high metal utilization. The largest casting up to ten tons, mainly for casting large-scale thick-walled precision castings and casting a single batch of small quantities of die, forging die, plastic mold, metal mold, die-casting mold, glass mold and other molds. The life of the ceramic casting mold can be comparable to that of the mold made by the machining method, and the manufacturing cost is lower than that of the mold made by the machining method.

Sand casting

In all casting production, 60 ~ 70% of the castings are produced with sand, and about 70% of them are made of clay sand. The main reason is that sand casting is less costly than other casting methods, the production process is simple and the production cycle is short. So the car like the engine cylinder block, cylinder head, crankshaft and other castings are made with clay wet sand production process. When the wet type can not meet the requirements and then consider the use of clay sand dry sand, dry sand or other sand. Clay wet sand casting casting weight from a few kilograms up to dozens of kilograms, while the clay dry production of castings can weigh tens of tons.

In general, for large castings, cast iron pieces can be made of resin self-hardened sand, cast steel can be produced with water glass sand type, you can get the size of precision, smooth surface of the casting, but the higher cost.

Of course, the precision of casting, surface finish, material density and microstructure, mechanical properties, etc., of sand casting are often poor, so when casting these performance requirements is higher, other casting methods, such as melting Wax) casting, die casting, low pressure casting and so on.