Have you been in manufacturing industries before? If yes, you know that high-pressure die casting is the most preferred technique for a good reason. The manufacturing technique helps countless industries produce complex designs of metal parts with high dimensional accuracy and great efficiency.
Wondering how the process begins? High-pressure die casting begins with melting your desired metal (Aluminum, Zinc, Magnesium, and Copper) under high temperatures. After obtaining the molten metal, it’s forced under high pressure into a mold shaped according to your desired shapes. After a while, the metal solidifies with respect to the mold shape, and there you have it, a well-designed metal part.
If you want to use high-pressure die casting in your next manufacturing project, it’s best to understand the casting parameters involved. Here is why – the quality of high-pressure die casting is largely determined by the process and parameters.
At Sunrise Metal, we are experts in High-Pressure Die Casting, and we understand the importance of controlling the parameters of the process to ensure the quality of our castings. Here are some of the key parameters that make all the difference:
Process Parameters in High-Pressure Die Casting – Everything You Need to Know
Melt Holding Time
Control time is a very important factor in the high-pressure die-casting process. There are four areas that manufacturers need to be cautious of when controlling time- the filling time, pressurization time, holding time, and retention time.
The melt-holding time, or perhaps the holding time, is the duration of time molten metal is held in the furnace before it is injected into the die-casting mold. This die casting parameter is very crucial as it helps remove all the impurities in the molten metal. During the process, the impurities rise to the surface and are later skimmed off.
Since all metals have different properties, including melting points, we only utilize high-quality furnaces with a controlled atmosphere. This ensures that every type of metal we deal with can go to the furnace and remove all impurities.
Pouring Velocity
The pouring velocity is the speed at which the molten metal becomes injected into the die-casting mold. The filling speed is mostly affected by the pouring temperatures. If the pouring temperature is high, the viscosity of the molten metal is low, and the fluidity increases. When the fluidity increases, the filling speed also increases.
The filling speed is also a determining factor in the quality of metal parts produced. When the filling speed is low, the casting is unclear and cannot be formed.
When the filling speed is high, castings with high surface quality can be achieved even with low injection pressure. However, you have to strike a balance. Too high mold filling speed can result in undesired results. Thus, we only use high-pressure die-casting machines that allow us to control the pouring velocity precisely.
Pouring Time
As mentioned above, control time greatly affects the quality of the metal products, which also applies to the pouring time. If you don’t have an idea of what pouring time is, don’t worry; you are many on the train.
Pouring time is the time required for the molten metal to be injected into the die-casting mold until it is filled. The pouring time can differ based on the type of parts. For example, the filling time of galvanized parts is 0.02 seconds, while fuel injection parts are 0.04 seconds. For high-quality product parts, we use computer-controlled die-casting machines that allow us to monitor the pouring time and ensure it’s correct.
Mold Temperature at the Time of Pouring
The mold temperature at the time of pouring is important because it affects the way the metal solidifies, dimensional accuracy, and the life of the die casting die. The standard temperature of the mold should be ⅓ of the alloy fluid pouring temperature.
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When the mold temperature is below 130 degrees, the casting may not form; if it does, it gets fractures and other defects. When the temperature is close to ideal (130-150 degrees), the casting is formed, but the quality is unstable. The most suitable temperature is 150-300 degrees. Molding temperatures higher than this will only generate surface bubbles, welding, and shrinkage.
We use a preheater in this die-casting parameter to ensure the mold is at the correct temperature before the molten metal is injected.
Gate and Riser Design
The gate and riser design is also a die-casting parameter that controls the flow of molten metal and induces directional solidification. The gate, as the name suggests, serves as an entry point for the molten metal into the die cavity, controlling the flow and distribution and preventing defects like porosity and air entrapment.
Risers act as heat reservoirs of molten metal to compensate for shrinkage during solidification, reducing the risks of voids. The type of gate design affects the quality of metal parts. Luckily, at Sunrise Metals, we have qualified engineers who design gates and risers optimized for each casting.
Degasification
Degasification is an important die-casting parameter that involves the removal of dissolved gasses such as nitrogen and hydrogen from the molten metal to enhance casting quality. When molten metal is subjected to high pressure, it absorbs gasses from the atmosphere or the raw material. If not removed, these gasses can cause defects and weaken mechanical properties.
We mainly use a degassing unit in the form of tablets or granules to remove the air bubbles. The tablets are added to the molten metal, after which they dissolve the gasses. These gasses later rise to the surface and are removed.
Preheat Temperature
Preheating temperature is done to reduce the risk of premature solidification, ensuring a complete fill. The temperatures of the die and the molten metal are raised to specific levels before the casting process to help ensure the molten metal fills the die-casting mold without leaving any gaps.
To ensure we get a good fill of the molten metal into the die, we set the preheating temperature above the melting point of the metal being used. The result? High-quality components with accurate dimensions and surface finish.
Die Coat Thickness and Material
Now comes the final die casting parameters– Die coat thickness and material. This step determines the quality of the surface finish. If the die coat material applied on the metal is of bad quality, the metal will not have a smooth surface finish. Moreover, if the coat is applied in large quantities, it may result in excessive buildup that may affect the dimensional accuracy.
At Sunrise Metals, we use a die coat, which is usually ceramic material, to give the metal part a smooth surface finish. We also maintain a thickness of 0.15 to 0.5mm ensuring that the dimensional accuracy of the metal is achieved and it’s also easier to remove the metal from the mold.
As we wrap up, these are the 8 die casting parameters in high-pressure die casting. It is important to note that each process affects the quality of the final product. If you miss out on one step, you will get low-quality metal parts. To ensure that you are on the safe side, ensure you hire an experienced company to produce high-quality parts.
Sunrise Metals is one of the best aluminum die-casting manufacturers in China.Our expertise and die-casting machines ensure we deliver high-quality and durable metal products. Trust us to get the job done right in your next manufacturing project.