EATHU takes you through the characteristics of gravity die casting of aluminum alloy

This paper introduces the characteristics of gravity casting of aluminum alloy

Gravity casting of aluminum alloy refers to the process of injecting aluminum liquid into the mold by gravity under the action of the earth's gravity. Generalized gravity casting Gravity casting can be divided into sand casting, metal mold casting, lost mold casting. Narrow gravity casting refers to metal mold casting. Gravity casting can be divided into vertical hand casting, tilt casting is now the most widely used metal mold casting. The mold is made of heat-resistant alloy steel, and the strength, size and appearance of the cast aluminum parts are higher than that of other casting processes. Gravity casting is generally to manually pour liquid aluminum into the gate, and obtain the sample by the metal liquid self-weight filling, exhaust, cooling, and mold opening. The process flow is generally as follows: molten aluminum liquid, pouring and filling, exhaust, cooling, mold opening, cleaning, heat treatment, processing.

The characteristics of aluminum alloy gravity casting are:

1. The surface finish of the product is not high, and it is easy to produce pits after shot blasting, generally reaching Ra6.3 or even Ra1.6.

2. Aluminum castings have few internal pores, so they can be heat treated.

3. The product has low density, slightly poor strength, but high elongation.

4. Low mold cost and long service life.

5. Low production efficiency, which increases production costs.

6. The process is simple and not suitable for the production of thin-walled parts.

7. Special aluminum alloys with low fluidity can be used, which cannot be heat treated.

8. The product has high air tightness, high casting strength and surface hardness, but the elongation is low, and the wall thickness is too large to produce porosity.

9. High mold cost and short service life.

10. Thin-walled parts can be produced with a small machining allowance.

When choosing which process to produce products, the choice is mainly based on the wall thickness of the workpiece. When the wall thickness of the product is greater than 8mm, the die casting will cause a large number of pores in the wall, so the product with a thicker wall can be completed by gravity casting.

Introduction to gravity casting of aluminum alloy; Pressure casting is divided into high pressure and low pressure.

High pressure casting is what we usually call die casting, the aluminum liquid is poured into the pressure chamber, and the pressure is filled with the cavity at high speed, and the aluminum liquid is solidified under pressure to form aluminum castings.

High pressure die casting: liquid or semi-solid metal or alloy, or liquid metal or alloy containing reinforcement phase, high speed under high pressure into the die casting cavity, metal or alloy solidified under pressure to form a casting method. The common pressure in die casting is 4 to 500 MPa, and the metal filling speed is 0.5-120 m/s, so the filling time of molten metal is very short, about 0.01 to 0.2 seconds to fill the cavity (depending on the size of the casting). Therefore, high pressure and high speed is the fundamental difference between die casting and other casting methods, and it is also an important feature.