Introduction to Gravity Casting, Casting, High Pressure Casting and Low Pressure Casting Process
Introduction to gravity casting:
Gravity casting refers to the process of injecting molten metal into a mold under the action of gravity of the earth, also called casting. Generalized gravity casting includes sand casting, metal casting, investment casting, lost foam casting, mud casting, etc.; narrow learning of gravity casting refers to metal casting. The molten metal is generally poured into the gate by hand, and the product is obtained by filling the cavity with the self-weight of the molten metal, exhausting, cooling, and opening the mold. The process flow is: melting, pouring filling, exhausting, cooling, mold opening, heat treatment and next machining processing.
Die casting introduction:
Pressure casting is divided into high pressure casting and low pressure casting.
High-pressure casting is a casting method in which a molten alloy liquid is poured into a pressure chamber, a cavity of a steel mold is filled at a high speed, and the alloy liquid is solidified under pressure to form a casting. The main features of high pressure die casting that distinguish it from other casting methods are high pressure and high speed.
1 The molten metal fills the cavity under pressure and crystallizes and solidifies at a higher pressure. The common pressure is 15-100 MPa.
2 The metal liquid fills the cavity at high speed, usually at 10-50 m/s, and some can also exceed 80 m/s (the line speed of the cavity introduced into the cavity through the ingate), so molten metal filling time is extremely short, and the cavity can be filled within about 0.01-0.2 seconds (depending on the size of the casting).
The process of low-pressure casting is:
in the sealed crucible (or sealed can), the dry compressed air is introduced, and the molten metal rises along the riser pipe into the sprue under the action of the gas pressure, and smoothly passes through the sprue. Enter the cavity and maintain the gas pressure on the liquid level inside the crucible. Until the casting is completely solidified. Then, the gas pressure on the liquid surface is released, and the unsolidified metal liquid in the liquid riser flows back to the crucible. Reopen and remove the casting.
It can also be said that low pressure casting is a compromise between high pressure casting and gravity casting.