What is Aluminum Die Casting Service?

Aluminum die casting service is a metal forming process in which molten metal (such as molten aluminum alloy) is injected at high speed and under high pressure into a steel mold cavity, where it solidifies under pressure to form the casting. This process is somewhat analogous to plastic injection molding. The primary distinguishing features of die casting compared to other casting methods are its high pressure and high speed.

Aluminum Alloys in Die Casting Service

Cast aluminum alloys are classified into 4 main series based on their primary alloying elements: Al-Si (aluminum-silicon), Al-Cu (aluminum-copper), Al-Mg (aluminum-magnesium), and Al-Zn (aluminum-zinc). Aluminum alloys for die casting are generally from the aluminum-silicon series. Commonly used grades include ADC12 (A383), ADC10, and A360. Die casting molds must be made from tool steels, with typical materials including H13, 8407, 2344, 8418, and SKD61. Material selection should take into account the part’s structure, heat dissipation requirements, operating environment, and subsequent post-processing methods.

Grades	Excellent fluidity, good corrosion resistance, and low cost	Applications
A383 ADC12	Excellent fluidity, good corrosion resistance, low cost	Consumer electronics housings, small automotive parts
A380 ADC10	High strength, excellent dimensional stability	Automotive electronic control units, electromechanical housings
A360	Good corrosion resistance, good airtightness	Battery housings, sensor enclosures

The detailed properties of the above common aluminum alloys are as follows.

Properties/Grades	A383/ADC12	A380/ADC10	A360
Yield strength, MPa	230	214	170
Tensile strength, MPa	305	324	230
Hardness, HB	82	80	65
Density, g/cm3	2.68	2.74	2.68
Fatigue strength, MPa	70	97	70
Melting point, ℃	570~640	570~640	582~652

Aluminum Die Casting Process

The whole aluminum die casting service mainly includes mold manufacturing, injection of molten aluminum, part ejection, and post-processing.

#1 Mold Design

Aluminum alloy die casting requires that the produced castings meet industrial standards for shape and dimensions (e.g., Chinese standard GB/T1804-2000). Mold design should be based on actual requirements, emphasizing completeness and structural simplicity while ensuring good castability through die-casting feasibility analysis.

#2 Mold Manufacturing

After completing the mold design, the mold is fabricated according to the drawings, typically using CNC machining service and electrical discharge machining service. Mold precision is extremely high; any deviation can seriously affect casting quality. The finished mold is installed on specialized die casting equipment, followed by adjustment of process parameters.

#3 Injection of Molten Aluminum

Before casting, aluminum alloy material (e.g., ADC12) that meets the drawing specifications is prepared. The material is melted and injected into the mold. Before injection, precise measurement and temperature control are required to ensure casting quality.

#4 Mold Cooling

The molten aluminum in the mold solidifies rapidly within a short time. Cooling time and temperature are critical factors affecting workpiece quality.

#5 Part Ejection

After cooling, the mold is opened and the formed aluminum die casting is removed.

#6 Surface Treatment

After removal, the aluminum parts undergo trimming, electroplating, painting, and other surface treatments to meet appearance and surface quality requirements.

#7 Quality Assurance

Inspection of aluminum die castings includes dimensional accuracy, surface quality, and other criteria. Parts that pass inspection are deemed qualified.

Advantages of Aluminum Die Casting

Several advantages of aluminum die casting are as follows.

• High product quality. Castings achieve high dimensional accuracy and excellent surface finish, with higher strength and hardness. Strength is typically 25%–30% higher than sand casting, though elongation is reduced by about 70%. Parts exhibit good dimensional stability and interchangeability. Thin-walled, complex castings can be produced, with a minimum wall thickness for zinc die casting that can reach 0.3 mm; for aluminum die casting, that is 0.5 mm.
• High production efficiency. Machine productivity is high. For example, Chinese cold-chamber die casting machines can produce 600–700 aluminum shots in 8 hours, while small hot-chamber machines can achieve 3000–7000 shots in the same period.
• Cost advantages. Die cast aluminum parts can often be used directly without machining or with minimal machining, improving material efficiency, reducing equipment changeovers, and saving machining time. The parts are cost-effective. Combination die casting with other metals or non-metallic materials is also possible, saving assembly time and metal consumption.

Disadvantages of Aluminum Die Casting

Several disadvantages of aluminum die casting are as follows.

• High injection speed and unstable metal flow during die casting can cause porosity in castings produced by conventional methods, making heat treatment generally unsuitable.
• Producing castings with highly complex internal structures is difficult.
• Die life is relatively short, typically around 80,000 shots.
• Not suitable for small-batch production due to high mold manufacturing costs, which eliminate cost advantages in low volumes.

Aluminum die castings are generally not suitable for anodizing. The presence of numerous gas pores or shrinkage cavities after casting makes surface defects difficult to repair, resulting in poor coverage and appearance after oxidation.

Surface Treatment for Aluminum Die Casting

Common surface treatment options for aluminum die castings include electroplating, painting/spraying, sandblasting, and polishing. Anodizing is generally not recommended for die-cast aluminum due to gas porosity, shrinkage porosity, and solidification shrinkage that occur during cooling, which create microscopic defects and voids within the parts. These imperfections prevent the surface from achieving sufficient cleanliness and uniformity, which adversely affects the anodizing results.

Electroplating

Electroplating deposits metal ions onto the surface to enhance corrosion resistance, aesthetics, and mechanical properties. Common methods include chrome plating, nickel plating, copper plating, and zinc plating. Chrome plating is one of the most widely used, improving hardness, corrosion resistance, and visual appeal.

Painting

This involves applying coatings to the surface to improve corrosion resistance, wear resistance, and appearance. Common techniques include spray painting, powder coating, oil-based painting, and plastic spraying. Spray painting is among the most common, offering a wide range of colors and finishes while enhancing durability and corrosion protection.

Sand blasting

Sand blasting propels abrasive particles onto the surface to improve aesthetics and mechanical properties. Methods include dry and wet sandblasting, with dry sandblasting being the most common. It creates a textured surface layer that enhances both mechanical performance and visual quality.

Polishing

Polishing creates a smooth surface finish to improve aesthetics and mechanical properties. Common approaches include mechanical polishing and chemical polishing, with mechanical polishing being the most widely used. It produces a highly smooth surface, enhancing both appearance and performance.

Tolerance of Aluminum Die Casting

Tolerance	CT4-CT7, Tight tolerance up to 0.02mm
Wall Thickness	0.5mm
Number of Cycles	100,000
MOQs	500 pieces
Maximum Casting Weight	10 kg
Lead Time	as fast as 20 days

Applications of Aluminum Die Casting

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