How to design die casting molds for zinc alloys in a reasonable manner

[Feiyuwu]

The zinc alloy die-casting process is one of the most effective methods for producing metal components with a wide variety of intricate shapes because it possesses exceptional technical characteristics such as high material utilization, a short production cycle, and significant economic benefits. The majority of people who work in scientific and technological fields are faced with the challenging task of figuring out how die-casting manufacturers can extend the useful life of zinc alloy die-casting molds while also boosting economic benefits. This is a difficult task. There are a lot of things that can shorten or lengthen the lifespan of zinc alloy die-casting molds, which are already very complicated on the outside and the inside. 


After conducting in-depth research, experts determined that thermal fatigue, cracking, deformation, wear, and erosion are the most common types of failure that occur in zinc alloy die-casting molds. When the zinc alloy die-casting mold is put to use, it will crack due to the cyclic alternating stress that is brought on by hot and cold cycles as well as cyclic loads. This stress will cause the mold to fail. The zinc alloy die-casting mold breaks down as a result of the local stress that is generated during the process of clamping and demolding the die-casting mold. Formally speaking, each component of the Metal Plating has some degree of influence on the lifespan of the zinc alloy die-casting mold; however, the forming working parts, mold base, pouring system, and guide parts each have a significantly greater influence than the others. When designing the mold for the die-casting process, you should pay close attention to the points listed below.


1. It is important that the pressure center and the clamping center be aligned. 

When designing a mold, the layout of the mold cavities is a very important part, especially when more than one cavity is used in the same mold. This is the case when multiple cavities are used.On the other hand, in order to acquire components of a quality that is satisfactory, it is necessary to use a die-casting machine that possesses a greater clamping force. This will result in a certain amount of waste, which will, in turn, reduce the economic benefits.





2. To begin, if the die-casting machine's mold opening distance permits it

you should attempt to increase the thickness of the supporting plate and minimize the span between the mold feet. If this is successful, move on to the next step. Make every effort to use a mold body design that does not have through holes. A sleeve plate and a support plate make up the non-through-hole mold body. These plates are functionally equivalent to the through-hole mold body when they are combined into a single unit. Because of this, its rigidity is significantly higher than that of a through-hole mold body that is the same thickness.


3. The height of the ejector pin has to be the same as the height of the mold foot in order for it to function properly. The diameter of the ejector pin and its end should be increased as much as possible without having any effect on the mechanism that controls the ejection process. For example, the manifold cone, the area under the sprue, and any zinc die casting other areas in the dynamic mold cavity that have a thin wall. During the process of installing the zinc alloy die-casting mold, it is imperative that the end face of the ejector pin be aligned so that it is parallel to the parting surface. The expansion force that occurs during the production of die-casting is simultaneously transmitted to the movable mold bottom plate via the mold feet and ejector pins. This has the effect of effectively reducing the bending deformation of the mold body.


3.1 Determine the appropriate surface roughness levels and tolerances for a variety of different parts.
3.1The tolerance fit should be selected accurately so that the sliding part of the zinc alloy die-casting mold can move flexibly and prevent the molten metal from escaping at normal operating temperatures. This is necessary in order to prevent the molten metal from escaping.When the assembly size of the mold parts is selected to be too tight, a pre-tightening force will be formed, which will cause the zinc alloy die-casting mold to burst during the process of die-casting. When the matching accuracy level of the mold parts is selected with too large of a gap, the thermal conductivity will be reduced, and thermal fatigue will occur prematurely.


3.2 Zinc alloy die-casting molds should have an appropriate improvement made to their surface roughness level.
If the surface roughness of the die-casting mold parts is too smooth, it will have a negative impact on the surface quality of the die-casting parts and will shorten the lifespan of the zinc alloy die-casting mould.The surface roughness of a domestic die-casting mold's cavity, sprue, and diverter cone can generally reach Ra0. This is because domestic die-casting molds pay more attention to this aspect.On the other hand, there are fewer demands placed on the surface roughness of the runner, the overflow trough, the inner gate, and the overflow port.Who knows, but considering that the scratches, grinding lines, and milling cutter marks that are present in these parts to varying degrees are the primary cause of cracking in the die-casting mold, these parts should also reach Ra0.2 or above respectively

4. a pouring system and a cooling system that are reasonable
If the gating system of the zinc alloy die-casting mold is not designed properly, it will not only throw off the thermal balance of the mold, but it will also lower the quality of the parts that are die-cast from zinc alloy.It is recommended that the CNC machining parts location of the inner gate be chosen at the point that is the shortest distance from each section of the filling cavity.In order to prevent direct erosion and damage to the mold wall or core caused by the molten metal, it is important that the molten metal that is introduced from the inner gate first fill the areas of the deep cavity that are difficult to exhaust.

To reduce the amount of time needed for the filling process and to keep the thermal equilibrium of the zinc alloy die-casting mold intact, it is best to make the inner gate cross-sectional area as large as possible. In most cases, the cross-sectional area of the inner gate is somewhere  between thirty percent and fifty percent of the cross-sectional area of the nozzle. It is imperative that the runner keep an equal cross-sectional area or have a seamless transition. It is not advisable to undergo sudden contractions or expansions. In order to keep the temperature at this level, the cooling opinions of the zinc alloy die-casting molds ought to be generally arranged in an appropriate manner so as to achieve temperature balance.