There are many types of die casting, whose process can be divided into casting, mold, die casting.
What is die casting? Die casting is a precision casting method that uses a high pressure to force a metal solution into a complex metal mold. Die casting is abbreviated as die casting, which 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.
Casting dimensional accuracy is high, generally equivalent to 6~7, even up to 4;Good surface finish, generally equivalent to 5~8;
High strength and hardness, generally higher than sand casting by 25~30%, but extended the rate is reduced by about 70%;The size is stable and the interchangeability is good;The thin-walled complex casting can be die-cast. For example, the current zinc alloy die castings have a minimum wall thickness of 0.3 mm; custom aluminum alloy die casting up to 0.5 mm; the minimum cast hole diameter is 0.7 mm, and the minimum pitch is 0.75 mm.
High pressure aluminum casting is a process of pressing molten metal into a sealed mold cavity under pressure. It is held in place by a strong compression force until the metal solidifies. After solidification, the mold is released, opened, and the metal is released. After disassembly, the mold cavity is re-sealed for the next cycle. The stage of exerting extremely high pressure on the molten metal true injection plunger is called strengthening.
This process uses two different systems:
Hot chamber system. The injection system of the hot chamber machine is immersed in the molten metal of the blast furnace. When the piston is pumped, it forces the metal along the nozzle into the mold.
Cold room system. Generally speaking, small parts are made in hot chamber systems, while large parts are made in cold chamber systems because the size of hot chamber machines is limited. Compared with the hot chamber system, the pressure of the cold chamber system is higher.
Higher production speed.
Significantly reduced processing operations.
The welding agent has good surface finish.
Reducing the total weight of the welding agent can reduce the thickness of the plate wall.
The mold is durable, so the cost is reduced.
More complex parts can be made, reducing the number of parts required at a time.
After the molten metal fills the cavity, the casting is completely solidified under pressure. This period of time is called the holding time, and the holding time is related to the wall thickness of the casting and the metal crystallization temperature.
The time from the end of the holding pressure to the ejection of the casting from the mold opening is called the mold retention time. The mold retention time is determined according to the nature of the alloy, the wall thickness of the casting, and the structural characteristics. Generally, the minimum time for the die casting manufacturing process to eject without deformation or cracking is appropriate.
The average temperature of the molten metal poured into the injection chamber to the filling cavity, also known as the molten metal temperature, is usually at the lowest possible temperature, generally higher than the die-casting alloy, while ensuring the filling and quality requirements. The liquidus temperature is preferably 10~20 °C.
Die Casting Mold Temperature
The die-casting mold should be preheated before production, and a certain temperature should be maintained during the die-casting process. The die-casting mold is always in a hot state, which provides a basic guarantee for the filling and solidification of the alloy liquid. The zinc alloy is generally 150~200 °C; the preheating of the die casting mold can avoid the rapid cooling of the molten metal and reduce the fatigue stress of the die casting mold.