Pressure die casting process includes high pressure casting and low pressure casting.
High Pressure Die Casting Process
High-pressure casting is also call die-casting. Pour the aluminum liquid into the press chamber, and the mold cavity is filled with high pressure at high speed, and the aluminum liquid solidifies under pressure to form an aluminum casting. AdTech offers hot top casting parts for aluminum casting.
The commonly used pressure during die casting is 4 ～ 500MPa, and the metal filling speed is 0.5-120m / s. Therefore, the filling time of the molten metal is extremely short, which can fill the cavity in about 0.01-0.2 seconds (depending on the size of the casting). Therefore, high pressure and high speed are the fundamental difference between the die casting method and other casting methods.
Characteristics of Aluminum Alloy Die Castings
- The surface finish of the product is good, generally up to Ra6.3 or even Ra1.6.
- No heat treatment.
- The product has high airtightness, high casting strength and surface hardness, but low elongation, and too thick wall is prone to air holes.
- The mold cost is high and the service life is short.
- High production efficiency.
- Thin-walled parts can be produced with small processing allowance.
- Special aluminum alloy cannot be used.
Low Pressure Casting
Low-pressure casting: In the sealed crucible, pass dry compressed air, and the metal liquid rises into the sprue along the liquid riser under the action of gas pressure. Enter the cavity smoothly through the inner runner, and maintain the gas pressure on the liquid surface in the crucible until the casting completely solidifies. Then, the gas pressure on the liquid surface is released, and the unsolidified metal liquid in the riser flows back to the crucible. Open the mold again and remove the casting. The castings are densely structured, and it is easy to cast large and thin-walled complex castings without risers, and the metal recovery rate is 95%. No pollution, easy to realize automation. But the equipment cost is higher and the production efficiency is lower. Generally used for casting non-ferrous alloys.
Features of Aluminum Alloy Low Pressure Parts
- The product surface is worse than the die-casting parts than the gravity parts
- There are few pores in the aluminum castings, which can be heat-treated.
- The product has high air tightness, the casting strength and surface hardness are higher than die casting, but the elongation is lower than gravity.
- The mold cost is low and the service life is low.
- Production efficiency is lower than gravity and far lower than die casting.
- The process is complex and used to produce high-demand, high-quality castings.
- Special aluminum alloy with low fluidity can be used.