Analysis of the whole process of die casting aluminum alloy: a systematic guide from forming to finishing

Die casting aluminum alloy is a process of injecting molten aluminum alloy into metal molds (cavities) under high pressure and cooling it quickly to form parts with complex shapes and precise dimensions in one go. Aluminum alloys are ideally suited to the high-pressure die casting process because of their good fluidity, light weight, high strength and excellent corrosion resistance.

Precision die castings, after demolding, also need to go through machining, trimming, shot blasting or sand blasting and other secondary processing, as well as anodizing, plating, powder coating and other surface treatment, and ultimately to meet the assembly and appearance requirements. Common application areas include automobile engine shell, electronic radiator, pump shell, robot structure parts and so on.

1. Is aluminum alloy suitable for die casting?

Aluminum alloy is very suitable for die casting and is one of the most commonly used die casting metals.

(1) Good fluidity:

Aluminum alloy in 550-600 ℃ fluidity performance is good, can quickly fill the mold and fill the small cavity. 

(2) High strength-to-weight ratio:

Lightweight while maintaining high strength, conducive to structural weight reduction and energy-saving design. 

(3) Corrosion resistance and recyclability:

Aluminum alloy can be anodized to enhance corrosion resistance, and the recycling rate can reach more than 90%.  

(4) Mature technology:

Cold chamber die-casting machine is widely used, injection pressure up to 700-1500 bar, to ensure high precision and high-speed production. 

Advantages of die casting aluminum alloy:

High production efficiency: Die casting is the most efficient casting process;

Precision molding: dimensional tolerance ±0.05mm, surface roughness Ra3.2μm or less4;

Lightweight: widely used in lightweight demand fields such as automobiles and aviation7.

Limitations:

Castings are prone to pores and require special treatment.

Mold cost is high, life is about 80,000 molds, and small batch production is not economical.

2. Die casting aluminum alloy characteristics and common grades

Die casting aluminum alloy is through high pressure (usually 100-1000 MPa) will be molten aluminum alloy high speed (10-50 m/s) into the metal mold cavity, and in the pressure of rapid solidification molding casting process. Its core features are high pressure, high speed and precision molding, which is suitable for the production of complex thin-walled parts with a minimum wall thickness of up to 0.5 mm.

Aluminum alloy because of its low density, high thermal conductivity, corrosion resistance and good fluidity, become the ideal material for die casting process. Common grades include ADC12 (YL113), A380, etc.

Common Alloy Grades	Standard System	Main Composition (Approx.)	Key Characteristics	Typical Applications
A380	ASTM (American)	Si: 8-10%, Cu: 3-4%	High strength, good fluidity, balanced overall performance	Automotive components (transmission housings, brackets)
ADC12	JIS (Japanese)	Si: 10-13%, Cu: 1.5-3.5%	Excellent corrosion resistance, easy to electroplate	3C product casings, home appliance structural parts
A360	ASTM	Si: 9-10.5%, Fe ≤ 0.65%	Excellent fluidity, suitable for thin-walled parts	Electronic component housings, heat sinks
A383	ASTM	Si: 7.5-9.5%, Cu: 2-3%	Low cost, easy to form	General industrial parts, motor end covers
YZAlSi12	GB (Chinese)	Si: 11-13%, Fe ≤ 1.0%	Good resistance to die sticking, suitable for complex molds	Fan bases, bathroom accessories
EN AC-44100	EN (European)	Si: 8-10%, Cu: 2-3%	Low hot cracking tendency, suitable for thick-walled parts	Industrial pump bodies, motor brackets
AlSi10MgMn	ISO	Si: 9-11%, Mg: 0.2-0.5%	Wear and heat resistance, suitable for high-load conditions	Automotive wheels, compressor components
YZAlZn11Si7	GB	Zn: 9-13%, Si: 6-8%	Highest as-cast strength (≈320MPa)	Mechanical gears, high-strength structural parts

Remarks Description:

Equivalent relationship:

ADC12 ≈ American Standard A383 ≈ National Standard YZAlSi9Cu3

EN AC-44100 ≈ American Standard A380

Selection logic:

Thin wall / complex structure: Prefer A360, YZAlSi12 (higher silicon content, better flow).

High strength requirements: A380, YZAlZn11Si7 (Cu/Zn improves strength, but corrosion resistance decreases).

Surface treatment priority: ADC12 (low copper) is more suitable for plating / anodizing, A380 needs careful treatment for plating bonding.

Scrap recycling: Aluminum-silicon alloy (such as A360, ADC12) can be directly returned to the furnace, aluminum and zinc need to control impurities (such as Fe ≤ 1.2%).

3. Die casting aluminum alloy parts of the complete production process

The following is the complete process flow of die casting aluminum alloy products from die-casting molding, machining to surface treatment, divided into three stages for detailed introduction:

(1) die casting stage: the key starting point for molding

1) mold design and manufacture

According to the product structure and performance requirements, design a reasonable mold structure, including gate, exhaust system and cooling channel.

Molds are usually made of high-strength steel, and their precision and durability are ensured through CNC machining and heat treatment.

2) Melting and alloy preparation

Suitable aluminum alloy materials (e.g. A380, ADC12, etc.) are selected and heated to about 660°C in the melting furnace for complete melting.

During the melting process, degassing and deslagging are required to improve the casting quality.

3) High-pressure injection molding

Molten aluminum alloy is injected into a preheated mold cavity at an injection pressure of up to 1000 to 2000 MPa to ensure that the metal fills all details of the mold.

Rapid cooling allows the aluminum liquid to solidify quickly in the mold to form the desired casting shape.

4) Demolding and Preliminary Processing

After the casting has cooled, the mold is opened and the casting is pushed out using a thimble.

Preliminary deburring and trimming is carried out in preparation for the next machining stage.

(2) Machining Stage: Realization of Precision Dimensions and Functions

1) Deburring and Cleaning

Remove burrs and flying edges from the casting using mechanical or manual methods to ensure a smooth surface.

Remove oxidized skin and residues on the casting surface to prepare for subsequent processing.

2）Precision machining

According to the design requirements, use CNC machine tools to carry out drilling, milling, turning and other processing to ensure dimensional accuracy and shape and position tolerance.

For critical parts, multiple machining and measurement may be required to achieve high precision requirements.

3）Heat treatment (if required)

According to the material and performance requirements, annealing or solid solution treatment is carried out to improve the mechanical properties and stability of the castings.

Natural or artificial aging is required after heat treatment to release internal stresses.

(3) Surface treatment stage: to improve appearance and performance

1) Pre-treatment

Degrease, acid wash and alkali wash the castings to remove the oil and oxides on the surface to ensure the effect of subsequent treatment.

2）Surface enhancement treatment

According to the product requirements, choose the appropriate surface treatment method, such as sandblasting, shot blasting, etc., to improve the surface hardness and abrasion resistance.

3）Anodizing or other coatings

A dense oxide film is formed on the surface of aluminum alloy through anodic oxidation to improve corrosion resistance and decoration.

Electrophoretic coating, powder spraying or painting can also be carried out according to the requirements to give the product a variety of appearance effects.

4) Final inspection and packaging

The treated castings are comprehensively inspected for appearance, size and performance to ensure compliance with quality standards.

Qualified products are packed and ready for shipment.

Through the above three stages of precision machining and processing, die casting aluminum alloy products can meet the multiple requirements of high precision, high strength and aesthetics, widely used in automotive, electronics, machinery and other fields.

4.Typical products of die casting aluminum alloy parts

(1) automobile parts:

Engine block, gearbox shell, steering gear shell and other power transmission parts. 

(2) electronic radiator:

Server, power electronics, electric car motor radiator and shell. 

(3) Industrial pump valve parts:

Hydraulic pump casing, oil pump body and various valve bodies. 

(4) Communications and consumer electronics:

Base station antenna shells, LED lamps and lanterns shells, notebook heat sinks. 

(5) Household and power tools:

Electric drill shell, lithium tools body structure parts.

5.Summary

Through the detailed analysis of the various aspects of die casting, machining and surface treatment, we can see that the manufacturing of die casting aluminum alloy products is a highly integrated and precise process. The optimization of each step of the process directly affects the performance and quality of the final product.

Die casting aluminum alloy parts with high efficiency, lightweight advantage, in the automotive, electronics and other fields occupy a core position, the future of its application scene continues to expand.