Take you to understand the characteristics of aluminum alloy gravity casting
EATHU take you to understand the characteristics of aluminum alloy gravity casting
Aluminum alloy gravity casting refers to the process where molten aluminum is injected into molds under the influence of Earth's gravity. Broadly, gravity casting can be categorized into sand casting, metal mold steel casting, and lost wax casting, among others. Specifically, gravity casting refers to metal mold casting. Gravity casting techniques include vertical hand casting, but the most widely used method today is the tilted casting in metal mold steel casting. The molds are made from heat-resistant alloy steel, ensuring that the strength, dimensions, and appearance of the cast aluminum parts are superior to other casting processes.
In gravity casting, molten aluminum is manually poured into the sprue, and the sample is obtained through the self-filling, venting, cooling, and demolding of the metal liquid due to its own weight. The general process includes melting aluminum, pouring and filling the mold, venting, cooling, demolding, cleaning, heat treatment, and machining.
The characteristics of aluminum alloy gravity casting are as follows:
1. The surface finish of the products is not very high; after shot blasting, it is prone to pits, generally achieving Ra6.3 or even Ra1.6.
2. There are few internal gas pores in aluminum castings, allowing for heat treatment.
3. The density of the products is low, with slightly lower strength but high elongation.
4. The mold cost is low, and the mold has a long service life.
5. The production efficiency is low, thereby increasing production costs.
6. The process is simple and not suitable for producing thin-walled parts.
7. Low-flow special aluminum alloys can be used; they cannot undergo heat treatment.
8. The products have high air tightness, high casting strength, and surface hardness, but low elongation; excessive wall thickness may lead to gas pores.
9. The mold cost is high, and the service life is short.
10. Thin-walled parts can be produced with smaller machining allowances.
When choosing a production method for a product, the selection mainly depends on the thickness of the workpiece. When the product wall thickness is greater than 8mm, die casting can result in a large number of gas pores on the wall. Therefore, products with thicker walls can be completed using gravity casting.
Introduction to Aluminum Alloy Gravity Casting; die casting is divided into high pressure and low pressure.
High-pressure die casting, commonly known as die casting, involves pouring molten aluminum into a pressure chamber. Under high pressure, the aluminum fills the mold cavity rapidly, and the molten metal solidifies to form an aluminum casting.
High-pressure die casting: a casting method where liquid or semi-solid metal or alloy, or liquid metal or alloy containing reinforcing phases, is rapidly injected into the die cavity under high pressure, and the metal or alloy solidifies under pressure to form a casting. Common pressures in die casting range from 4 to 500 MPa, and the metal filling speed is 0.5 to 120 m/s. Therefore, the filling time for molten metal is very short, approximately 0.01-0.2 seconds to fill the mold cavity (depending on the size of the casting). Thus, high pressure and high speed are fundamental differences between die casting and other casting methods, representing essential characteristics of die casting.