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Solution for curing aluminum adhesion in die-casting molds, with three-dimensional control of materials, coatings, and processes

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  • Release time: 2026-11-07

Solution for curing aluminum adhesion in die-casting molds, with three-dimensional control of materials, coatings, and processes
Aluminum sticking is the most troublesome and repetitive problem in die casting. Relying solely on frequent polishing to treat the symptoms is not the root cause. Xinfeng Machinery has sorted out the entire prevention and control logic of molds, aluminum liquid, and processes.
1、 The underlying mechanism of aluminum adhesion
High temperature aluminum liquid infiltrates the surface of the steel mold, generating intermetallic compound FeAl ₓ between iron and aluminum, forming a hard aluminum iron alloy layer that firmly adheres to the mold cavity, that is, sticking aluminum. A356 has stronger infiltration and a significantly higher risk of aluminum adhesion compared to ADC12. Microscopic scratches and polishing patterns on the surface of the mold cavity are the preferred attachment points for aluminum bonding, and rough surfaces are more prone to rooting.
2、 Mold base material and surface protection scheme
High purity H13 and 8407 steel have fewer impurities and better anti stick aluminum than ordinary H13. Mirror polishing Ra0.02-0.05, reducing micro anchoring points; Prioritize ion Nitriding Primer+AlTiN Coating Composite Solution to Block Aluminum Iron Reaction. TiN coating is suitable for intermittent production with moderate anti stick aluminum and limited budget; DLC coating is suitable for low temperature and low load top pin positions, but not resistant to long-term high temperature die-casting. The alloy wheel mold gate and erosion zone are high-risk areas for aluminum adhesion, with priority given to local coating.
3、 Aluminum liquid side control reduces the probability of aluminum sticking
Aluminum liquid contains high levels of hydrogen and oxide inclusions, which can accelerate the adhesion of aluminum. Control the proportion of recycled materials, remove air from the rotor, filter and purify to reduce the inclusion of alumina. The temperature of the aluminum liquid should not be too high, as overheating will exacerbate the infiltration reaction; A356 recommends aluminum liquid temperature at 720-740 ℃, and ADC12 controls at 680-710 ℃. Aluminum liquid with high impurities and repeated overheating, even the best coating is prone to quickly adhere to aluminum.
4、 Release agent, mold temperature and spraying process
The mold temperature is too low, and the aluminum liquid is rapidly cooled, but it is easy to form an unstable oxide film; Excessive mold temperature accelerates aluminum iron interdiffusion. A356 stable mold temperature is 200-240 ℃, ADC12 is 180-220 ℃. The release agent uses a special formula for anti stick aluminum, with uniform atomization and no excessive accumulation; Excessive spraying causes temperature fluctuations in the mold cavity, which in turn triggers local aluminum adhesion.
5、 Standard cleaning after sticking aluminum
Do not forcefully scrape the mold cavity with a hard steel shovel, as it will leave scratches and lead to faster adhesion of aluminum in the future. Priority soft copper shovel, ultrasonic cleaning, gentle polishing; The adhesive aluminum has corroded the substrate, and after polishing, it needs to be recoated. Low pressure casting has a gentle flow rate and a much lower frequency of aluminum adhesion compared to high-pressure casting. Google's "die casting mold solving solution" is a high-frequency search term for overseas process engineers.
FAQ
Is aluminum adhesion and erosion the same thing?
Adhesive aluminum is the adhesion of aluminum iron compounds; Ablation is the erosion and corrosion of steel by aluminum liquid, which belongs to a more severe stage.
Will the coating stick to aluminum if it falls off?
The coating failure area loses isolation and quickly becomes sticky with aluminum.
3. The brighter the polishing, the less likely it is to stick to aluminum?
Within a reasonable roughness range, mirror polishing is the basic means of anti sticking aluminum.
Can we completely eliminate aluminum adhesion by adding release agents?
No, it can only be alleviated. The root cause is the high-temperature reaction between aluminum and iron.
Is A356 aluminum bonding more difficult to handle than ADC12?
Yes, A356 has stronger infiltration and higher protection requirements.
How long does it take to check the adhesion of aluminum during continuous production?
A356 wheel hub mold inspection every 300-500 molds; The ADC12 casing can be elongated.
Can nitriding alone prevent aluminum from sticking?
It can alleviate the problem of aluminum adhesion in the nitride layer even during long-term high-temperature continuous production.
8. How to handle the top needle sticking aluminum?
Apply AlTiN or DLC coating to the top pin and control the surface temperature of the top pin.

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