Precision casting process wax mold precision casting, also known as lost wax casting or investment casting.
Casting method is: the first to do castings made from wax material model, and the model with same material welded to the gate, on the rod made module (can be a single for a group of large castings), on the module surface dip in refractory coating (a mixture of sodium silicate and silica sol and fine sand), then sprinkle with refractory ore, (moistening slurry, sanding to repeated several times, make the sand thick enough), awaiting the dry cured, heated the module, the wax material from the gate out, forming a shell. The empty shell is roasted to form a solid mold, and the liquid metal is poured through the gate and condensed to form a metal casting.
Wax die casting in China originated in the Bronze Age, has a history of more than two thousand years. Now has been widely used in various industries, such as aerospace, petrochemical, weapons and ships, machinery manufacturing, household appliances and instrumentation.
Wax die casting has many advantages: it can produce complex castings and thin wall parts with small holes; Suitable for all kinds of metals and alloys; High manufacturing accuracy.
According to the different wax materials and shell materials, wax die casting is divided into: low temperature wax -- sodium silicate process;Medium temperature wax-silica sol process;Composite process
Low - temperature wax - water glass process commonly used molding equipment
From left to right, the names are: all-in-one machine for making paste and waxing, pneumatic wax-filling machine, puddle and injection, hydraulic wax-filling machine.
Puddle the wax machine to melt the wax barrel
In the 1940s, the ion exchange process of silicon sol was developed by the American company NALCO. Later, it was perfected by the American company dupont in the 1950s and 1960s. At present, it is the most mature and widely used process.This process has certain requirements for materials such as water glass, ion exchange resin and operation technology, which are the weakness of domestic products.Relatively speaking, the process of one-step hydrolysis of silica powder is relatively simple and is widely used in China.However, silica sol prepared by this method usually has a particle size of about 10-20 nanometers, and the interface between particles is not clear, the morphology is non-spherical and cannot be controlled, and the interface between particles is not clear, so it is usually used in casting and other industries in large quantities, but not in many fields with higher requirements such as precision polishing and catalyst.Compared with the internationally renowned silica sol brand, the main disadvantages of domestic silica sol at present are high impurity content, no strict control of particle size, no strict detection of particles than the surface, low concentration of silica, poor stability under acidic or neutral conditions, short service cycle, more or less with a little color, less variety and so on.At present the internationally renowned silica sol brand has dupont to pass reiss LUDOX series.