Those in die casting industry know that producing a qualified die-cast part is far more complex than simply "pouring molten aluminum into the mold." From mold preheating to casting ejection, each step follows strict operational logic. A single mistake can lead to defects such as porosity, insufficient material, and mold sticking, rendering the entire batch unusable!

 

Today, we'll break down 7 core processes of high-pressure die casting, combining frontline production experience and industry standards. Whether you're a newcomer or a seasoned veteran, you can follow these steps and avoid common pitfalls!

Primary task before die casting is to "warm up" the mold – turn on mold temperature controller and stabilize mold temperature at around 220℃ (this can be slightly adjusted for different products, but should maintain a fluctuation of ±10℃).
- Why Can't This Be Skipped? If mold temperature is too low, molten aluminum will cool rapidly upon entry, directly leading to cold shuts and insufficient filling. If temperature is too high, product will stick to mold, solidification time will be prolonged, reducing production efficiency.
- Key Standard: Production must only begin after all areas of mold have a uniform temperature to avoid uneven stress, deformation, and cracking caused by localized temperature differences.

After mold is preheated, contour painting robot takes over, performing two core actions:
- Spraying a precise amount of release agent: Neither too much nor too little – too much will leave residue, causing bubbles and pinholes on product surface; too little will not provide lubrication, making product prone to damage during ejection.
- Drying Cavity: Mold cavity must be thoroughly dried after spraying. Residual moisture from release agent will turn into gas at high temperatures, becoming trapped in molten aluminum and forming pores, affecting product's density.

This step is "sealing stage" of die casting: moving mold and fixed mold close precisely, forming a completely sealed cavity, ready for filling of molten aluminum.
- Core Requirements: Mold must close tightly without gaps; otherwise, during high-pressure filling, molten aluminum will overflow from gaps, forming flash and burrs, wasting material and affecting product dimensional accuracy.
- Industry Standards: Mold closing force must be precisely matched to projected area of product to avoid leakage due to excessive looseness or damage to mold due to excessive tightness.

Robotic arm precisely grasps a fixed quantity of molten aluminum and slowly pours it into pressure chamber (material pipe) of die casting machine. Core of this step is "precise quantity control."

 

- Too much: Excess aluminum liquid increases material loss and may cause excessive pressure during injection, damaging mold.
- Too little: Insufficient aluminum liquid will not fill mold cavity, directly causing material shortages and product scrap.
- Key points for operation: Aluminum liquid should be poured smoothly to avoid splashing and air entrapment, which will affect subsequent molding.

This is the most crucial step in die casting! Injection piston of die casting machine propels aluminum liquid at high speed and high pressure, quickly filling mold cavity along gating system. Simultaneously, vacuum valve system activates, evacuating air from mold cavity.
- Speed and pressure: High speed ensures aluminum liquid fills mold cavity before solidification (especially for thin-walled parts), while high pressure allows aluminum liquid to fully adhere to mold, improving product's detail molding rate.
- Vacuum function: Vacuuming completely removes air from mold cavity, preventing air entrapment and porosity in aluminum liquid. This is a key process for high-airtightness products (such as automotive cylinder blocks and hydraulic valve bodies).

After molten aluminum fills mold cavity, injection piston does not immediately retract but continues to maintain a certain pressure, allowing molten metal to crystallize and solidify under pressure.
- Core Purpose: To prevent shrinkage cavities and porosity caused by volume contraction during solidification, thus improving internal density and mechanical strength of product.
- Time Standard: Holding pressure time needs to be adjusted according to product thickness. For thin-walled parts, it is generally 3-5 seconds, while for thick-walled parts, it can be extended to 8-10 seconds to ensure complete solidification.

Once casting has completely solidified, moving mold and fixed mold separate, and ejection mechanism smoothly ejects casting from cavity. Finally, casting is removed by a robot or manually, completing the entire die-casting process.
- Precautions: Ejection force should be even to avoid excessive force that could deform or damage casting. After removal, any residual impurities in mold cavity must be cleaned promptly to prepare for next mold production.
Die casting is no small matter; every step is crucial.
Seven processes of high-pressure die casting may seem simple, but they are actually interconnected—inadequate mold preheating, excessive release agent application, insufficient holding pressure time… neglecting any detail can lead to product scrap.
Mastering these seven standard processes will be invaluable, whether for beginners to quickly get started or for experienced workers to standardize operations and improve yield rates. Share this with your colleagues in workshop, and together we can use these standard processes to control every step of process, making production more efficient and products of higher quality!