The "Genetic Engineering" of Aluminum Profiles: Decoding Melting & Casting Processes

In the production chain of aluminum profiles, the melting and casting process serves as the "architect of material genetics." It not only determines the "lineage" (alloy composition) of aluminum profiles but also acts as a precise "gene editor," laying the performance foundation for subsequenT Extrusion and processing through high-temperature 淬炼 (quenching) and mold shaping. Today, we step into this industrially charming "origin of materials" to uncover the first code of aluminum profile creation.

Process Overview: The Transformation from "Metal Cubes" to Billets

The story of aluminum profiles begins with stacks of silvery-gray aluminum ingots and bags of powdery alloying elements (such as magnesium, silicon, copper, manganese, etc.). These seemingly ordinary raw materials undergo a "phoenix-like rebirth" in high-temperature furnaces: aluminum ingots act as the "base canvas," while alloying elements are the "palette." Blending together at 700–800°C, they solidify into cylindrical aluminum billets or flat slabs—these rough-looking blanks are the "raw material heart" for subsequent extrusion.

Core Steps: Every Process is a "Moat" for Performance

Mixing: Milligram-Level Precision in Composition Design
Engineers develop strict mixing formulas using spectral analysis based on the target profile’s application (e.g., 6063 for construction, 7075 for aerospace). For instance, producing 6063 alloy for construction requires precise control of magnesium (0.8%–1.2%) and silicon (0.4%–0.8%) to balance extrusion performance and surface treatment adaptability. In contrast, aerospace-grade 7075 alloy incorporates zinc and copper to push tensile strength above 500MPa.
Metaphor: This step is like "crafting a magical potion," where the ratio of each element is the "spell" to unlock specific properties.

Melting: Purifying Impurities in a "Steel Furnace"
Once the mixture enters the melting furnace, high heat turns the metal into flowing "liquid gold." The key here is "impurity removal": inert gases (e.g., argon) are bubbled through the melt to absorb and carry away harmful gases like hydrogen, while ceramic filter plates or foam ceramics act as "metal sieves" to trap solid impurities like aluminum oxide inclusions. This reduces impurity content from 0.3% to below 0.05%, eliminating risks for subsequent processing.

Casting: Molds endow Metals with "Initial Form"
Pure Aluminum Liquid is poured into casting molds, commonly semi-continuous casting molds (for long billets) or static casting molds (for slabs). In semi-continuous casting, aluminum liquid is injected from the top of the crystallizer, and a bottom water-cooling system solidifies and pulls the metal downward to form cylindrical billets (100–500mm diameter, up to 6m long). This process minimizes pores and segregation, ensuring a uniform internal structure in the blanks.
Data: A large melting furnace can process 5–10 tons of aluminum liquid per batch, equivalent to casting 3,000 standard construction billets.

The Mystery of Alloy Composition: Different "Genes" Dictate Different "Destinies"

The alloy composition determined during melting and casting directly influences the profile’s "life path":

6063 Alloy (common for architectural doors/windows): Magnesium and silicon form Mg₂Si strengthening phases, providing excellent extrusion performance (for complex cross-sections) and anodizing adaptability (easy surface coloring). With a density of just 2.7g/cm³, it is 60% lighter than steel.

6061 Alloy (preferred for automotive parts): Adding copper (0.15%–0.4%) enhances weldability, making it suitable for chassis frames that require assembly. In T6 heat-treated state, its tensile strength reaches 310MPa, withstanding impact forces during high-speed driving.

7075 Alloy (a "hardcore material" for aerospace): High zinc content (5.6%–6.1%) gives it "steel-level" strength (≥500MPa) while maintaining aluminum’s lightweight nature. It becomes the core material for rocket engine brackets and aircraft wing ribs, stable in extreme environments from -200°C to 150°C.

Process Value: Laying the "Foundational Competitiveness" of Aluminum Profiles

Why is melting and casting the "decisive first step"?

Quality Foundation: A 0.1% reduction in impurity content can extend the profile’s corrosion resistance life by over 10%. A composition deviation of more than 0.05% may accelerate mold wear during extrusion.

Cost Control: Precise mixing calculations reduce waste of expensive alloying elements (e.g., copper, zinc), while semi-continuous casting increases material yield from 80% to over 95%.

Innovation Starting Point: The emerging "high-magnesium lightweighT Aluminum" (5%–10% lower density than traditional aluminum) adjusts magnesium content and optimizes casting during melting to achieve "weight reduction without strength loss," ideal for new energy vehicle battery trays.

Every Aluminum Billet is a Legacy of "Industrial Genes"

The seemingly simple transformation from ingots to billets is a deep fusion of materials science and engineering. Melting and casting act as a "silent creator," injecting the initial "performance genes" into aluminum profiles through high heat and mold coordination. When these blanks enter subsequent extrusion and surface treatment, their "genetic codes" are further activated, eventually becoming the strong and beautiful doors/windows in buildings, lightweight and robust frames in cars, and extreme-resistant structures in aerospace—the starting point of it all lies in the golden melt surging in the furnace and the metal blanks quietly solidifying in the mold.

In the world of aluminum profiles, every process pursues "perfection," and melting and casting mark the beginning of this pursuit.