Aluminum alloy die-casting molds usually require several materials, each of which plays a certain role in the die-casting mold. Selecting the appropriate mold material is one of the keys to the success or failure of die-casting mold design. Mainly starting from the working conditions of aluminum alloy die-casting molds, the performance requirements of mold materials are proposed based on the failure modes of the molds. By introducing the commonly used materials and heat treatment requirements of die-casting molds, the material selection of each part of the mold is analyzed. At the same time, the assembly of the die-casting mold and the dimensions of the parts are also introduced. Specific technical requirements for geometric tolerances.

Technical requirements for appearance and installation parts of aluminum alloy die-casting molds

The shape and installation location of the aluminum alloy die-casting mold should meet the following technical requirements:

(1) The edges of each formwork should be chamfered at 2×45°, and the installation surface should be smooth and flat, with no traces of protruding screw heads, pins, burrs, or bruises.

(2) Put obvious marks on the non-working surface of the mold in a conspicuous place, including the following: product code, mold number, manufacturing date, and the name or code of the mold manufacturer.

(3) There are screw holes for lifting on the movable and fixed molds respectively. Parts with larger mass (>25kg) should also be provided with screw holes for lifting. The effective thread depth of the screw hole is not less than 1.5 times the diameter of the screw hole.

(4) The relevant dimensions of the mold installation part should comply with the corresponding dimensions of the selected die-casting machine, and should be easy to assemble and disassemble. The installation aperture and depth of the pressure chamber must be strictly checked.

(5) Except for guide bushing holes and oblique pin holes on the parting surface, all process holes and screw holes in the mold manufacturing process should be blocked and flush with the parting surface.

Dimensional tolerances and fits of aluminum alloy die-casting mold structural parts

Die-casting molds work at high temperatures. Therefore, when selecting the matching tolerances of aluminum alloy die-casting mold parts, it is not only required to achieve a certain assembly accuracy at room temperature, but also to ensure that the structural dimensions of each part are stable and reliable at operating temperature. Especially parts that are in direct contact with the metal melt are subject to high pressure, high speed and thermal alternating stress during the filling process, and the matching gaps with other parts are prone to change, affecting the normal progress of die casting.

In addition to the temperature, the change in the fit gap is also related to the material, shape, volume of the mold parts, the degree of heating of the working part and the actual fit properties after processing and assembly. Therefore, the matching state of die-casting mold parts during operation is very complex. Usually the fit clearance should meet the following two requirements:

① For parts that are fixed after assembly, there will be no positional deviation under the impact of metal melt. The deformation after thermal expansion cannot make the fit too tight, which will severely overload the mold insert and sleeve plate locally, causing the mold to crack.

② For parts that move during operation, after being heated, the matching properties of the clearance fit should be maintained to ensure normal movement, and during the filling process, the metal melt will not escape into the fit gap.