Die casting details

1. Structural strength of the mold

In order to reduce the manufacturing cost of the mold, it is not advisable to forcibly reduce the size of the mold material.

Reducing the size only reduces the cost of materials, while other processing costs remain basically unchanged. The biggest impact is the strength of the mold. If the strength is not enough, it is directly related to the deformation of the entire mold during production and the stability of the operation of core pulling, ejection and other mechanisms. Therefore, the size plays a decisive role in the quality of the product, and may even cause the mold to not be put into production. Therefore, the sufficient strength of the mold structure is an important guarantee for normal and stable production.

Because reducing size is the simplest, most direct, and most effective way to reduce costs, it is widely used. However, the consequence is that it will leave huge hidden dangers for future mass production, and such serious details are ignored or downplayed. I would like to ask, will this approach bring losses much greater than the steel cost saved? Therefore, please pay attention to the details of the structural strength of the mold.

2. Pouring and overflow system

Details that must be paid attention to when designing pouring and overflow systems:

(1) Details of structural features of parts

When analyzing parts, we should not only pay attention to where to separate the parts and where to facilitate feeding, but also carefully analyze the shape characteristics of the parts (for example, there are differences between arc and rectangular feeding methods); the wall thickness of various parts Changes (from thick to thin or from thin to thick will have a direct impact on the filling state); where the water flow will be blocked; where the direction of the water flow will be changed, etc., all details should be as clear as possible. Because this is the fundamental basis for designing the gating system.

(2)Details of designing the pouring system

Based on a careful analysis of the structural characteristics of the part, the basic principle of designing the gating system is to control the filling state as much as possible.

The details of the filling status mainly include: the order of feeding, where they meet, and where they end.

In order to achieve the required state during filling, when designing the gating system, more attention must be paid to the location and cross-sectional area of the inner gate, the form and cross-sectional area of the sprue, the form and cross-sectional area of the horizontal runner and the straight runner.

① Maximize the efficiency of the overflow system

There is a clear basis for designing the overflow system, and the overflow efficiency is the highest.

② Reduce energy consumption

Filling and overflowing are smooth, effectively reducing filling resistance. Therefore, the filling speed and material liquid temperature can be reduced accordingly, and stable product yields can be ensured.

In production, the method to deal with die-casting defects is to first increase the injection speed. If that doesn't work, increase the material temperature. The heat converted into kinetic energy increases. If coupled with the heat added by the heating of the material liquid, it will definitely be greater than the heat generated by smooth filling and basically no die-casting defects, and large values are difficult to calculate.

If the temperature and speed that the mold surface withstands exceeds the limit, premature erosion, cracking and other mold failures are not unexpected. A good gating system design is to avoid such things from happening, to extend the life of the mold as much as possible and to reduce costs.

Increasing the injection speed and material temperature not only directly affects the life of the mold and increases energy consumption, but also increases the loss of the die-casting machine, etc. These are direct added costs. If we pay attention to the details during design, it is entirely possible to avoid such a situation. Avoiding additional costs is equivalent to increasing additional benefits.

In addition, while meeting the normal filling requirements, minimizing the remaining material (the weight of the liquid material in the pouring runner and the number of slag bags) is also a good detail to reduce costs and increase revenue. Because the weight and quantity of remaining materials are reduced, it can not only reduce the requirements for clamping force and increase the service range of the machine, but also directly turn the cost of melting and returning materials into profits.

(3)Details of designing overflow system

By paying attention to the details of the gating system, the design of the overflow becomes simple. Because the places where the material liquid first arrives, converges, and is finally filled are all clear, so just add slag discharge and exhaust at these three places. The only thing to pay attention to is whether the cross-sectional area of the exhaust groove can meet the demand, otherwise it will increase the filling resistance and affect the filling state.

Specific methods on how to perform part analysis and design of gating and overflow systems have been published in the "Practical Techniques Booklet for Die Casting Molds" and "Clear in the Mind" edited by me, published by China Cast Technology, and listed on the China Cast WeChat Store. Aluminum alloy die-casting runner diagram" (as shown in the figure below) is explained in detail. I hope it can inspire you to a certain extent in the design and use of die-casting molds.

(4) Design details of the cooling system

When analyzing parts, we should not only pay attention to the changes in wall thickness (because wall thickness is the main basis for calculating heat), but also pay attention to the technical requirements everywhere (for example, post-processing is not allowed to have pores or shrinkage holes, etc.). After these problems are clarified, the cooling system can be designed based on the requirements of the mold structure (that is, to solve the problem of heat distribution and removal).

Ignoring the above details, the cooling system cannot be reasonably efficient, let alone adjust the production rhythm within a certain range.

If the temperature of the slider is much higher than the temperature of the mold frame, it will cause jamming. Especially in the case of automated operation, it is more likely to occur without manual flexible operation and observation at any time. The complete solution is to design the cooling system.

In short, the cooling system is extremely important for the stability, rhythm and mold life of die-casting production.