Vacuum Continuous Casting Machine

I. Core Requirements for Manufacturing Metal Billets (Rods / Tubes / Plates / Wires, etc.)

Metal billets serve as fundamental intermediate products in the high-performance alloy manufacturing supply chain. Their production must precisely match the downstream industries’ differential requirements for material, precision, performance, and capacity, which directly dictates the technological development and configuration of the Vacuum Continuous Casting Machine (VCCM).

1. Raw Material and Purity Requirements

Material Compatibility: Selection of corresponding metals and alloys based on application scenarios, such as nickel-based superalloys and titanium alloys for aerospace ¹; copper, silver, and other precious metals for electronics ²; and stainless steel/carbon steel for general machinery.

Purity Control: High-end sectors demand extremely stringent purity, driven by the urgent need for zero-defect materials.¹ For example, the impurity content in aerospace superalloys must be below 100 ppm; and electronic-grade copper billets require purity $\ge 99.99\%$.

VCCM Solution: The VCCM utilizes a high-vacuum environment (e.g., $6.67 \times 10^{-4} \text{ Pa}$) for vacuum treatment, which is its core process ³, effectively achieving degassing (removing highly active impurities like hydrogen, nitrogen, and oxygen) and inclusion removal.¹ This ensures ultra-high purity, high density, and pore-free castings.² VCCM’s associated purification modules can meet various purity standards.

2. Process and Precision Requirements

Dimensional Precision and Surface Quality: Billet quality standards demand internal soundness, chemical homogeneity, and surface integrity.

• Dimensional Precision: Rod diameter tolerance generally needs to be controlled within $\pm 0.1 \sim \pm 0.5 \text{ mm}$; wire diameter tolerance is stricter, requiring $\le \pm 0.02 \text{ mm}$. The VCCM must precisely regulate casting speed, cooling rate, and pulling force to ensure dimensional stability.

• Surface Quality: High-end billets require surfaces free of scale, porosity, or cracks, with roughness $Ra \le 0.8 \mu \text{m}$. The VCCM’s vacuum environment prevents molten metal oxidation ², and optimized crystallizer design and cooling systems enhance surface finish.⁴

Internal Performance and Microstructure: Macro-segregation must be strictly controlled, ensuring uniform chemical composition and fine grains. For high-performance forgings, subsequent forging steps cannot eliminate chemical non-uniformity formed during the casting phase.¹

VCCM Solution: Operating in a steady-state, continuous mode, VCCM delivers a steep and precisely controlled thermal gradient, achieving faster solidification rates than large, slow-cooled batch ingots. This rapid and uniform cooling minimizes the Primary Dendrite Arm Spacing (PDAS), resulting in a fine, uniform microstructure, reducing the risk of microporosity and hot tearing, and enabling optimized grain structure control.¹

3. Capacity and Automation Requirements

Scalability and Continuity: Industries like automotive, electronics, and construction require materials daily demand exceeding 10 tons. Equipment must support 24-hour continuous operation, with daily capacity of 5–50 tons, and large industrial lines potentially exceeding 100 tons.¹

Small-Batch and Customization: Scenarios like laboratory R&D or specialty material production require small-batch capacity (10–500 kg/batch). Equipment must support rapid material and specification changeovers (e.g., 2–4 hours for mold replacement and parameter adjustment).

VCCM Solution: The VCCM utilizes a continuous casting process ⁵, which enables high-throughput, efficient, and low-energy continuous operation.⁶ Horizontal VCCM (H-VCCM) is often used for small-diameter rods, tubes, or wires; while Vertical VCCM (V-VCCM) is suitable for large-diameter rods and ingots.¹ For high-precision, low-volume applications, vertical casting is typically preferred; for high-speed, high-throughput production, horizontal casting is more suitable.⁷ The future trajectory of VCCM includes integration with advanced sensor technology and Artificial Intelligence (AI) algorithms for real-time data analysis and automated defect detection.⁹

4. Specialized Performance Requirements

Extreme Environment Resistance: Aerospace and military billets require resistance to high temperatures ($\ge 800^\circ\text{C}$) and high pressure, e.g., Inconel 718 tensile strength $\ge 1240 \text{ MPa}$, and CMSX-4 single-crystal alloy tensile strength $\ge 1200 \text{ MPa}$ at elevated temperatures.¹⁰ The equipment must be compatible with melting and forming superalloys, controlling the grain structure to enhance high-temperature performance.¹

Biocompatibility: Billets for medical implants (e.g., titanium alloy rods) must be free of sensitizing impurities. The equipment requires medical-grade material handling processes and a sterile production environment.¹

Electrical/Thermal Conductivity: Electronic-grade copper and silver billets must ensure high electrical conductivity (copper $\ge 98\% \text{ IACS}$). The equipment must minimize oxides and pores in the molten metal to enhance conductive performance.²

Different types of metal billets, due to their structural properties and material advantages, cover a wide range of fields from traditional industries to high-end manufacturing. The varying demands drive the segmentation and upgrade of VCCM technology.

1. Rod/Bar Applications

2. Tube Applications

• Petrochemical Industry: Pipes for oil/gas transport, chemical reactor tubes, requiring stainless steel/corrosion-resistant alloys. Uniform wall thickness (tolerance $\le \pm 3\%$) and resistance to high-pressure corrosion are essential. VCCM must enhance the roundness and wall thickness consistency of the formed tubes.

• Medical Field: Infusion catheters, interventional therapy devices, requiring titanium alloys/medical-grade stainless steel. Small inner diameter ($\le 2 \text{ mm}$), high smoothness. VCCM requires micro-channel crystallizers and precise drawing techniques.¹

• Aerospace: Hydraulic system conduits, requiring superalloys. Resistance to high temperatures ($\ge 600^\circ\text{C}$) and fatigue. VCCM needs to control the internal stress distribution of the tubes.

3. Plate/Slab Applications

• Electronics Industry: Circuit board substrates, semiconductor packaging plates, requiring copper/aluminum. Ultra-thin (thickness $\le 0.1 \text{ mm}$), high electrical conductivity. VCCM must optimize the cooling rate to prevent plate deformation.²

• Construction Industry: Decorative panels, curtain wall cladding, requiring aluminum alloys. Flat surface, oxidation resistance. VCCM needs to improve plate dimensional stability and surface finish.

• Automotive Manufacturing: Body structure plates, engine heat sinks, requiring high-strength steel/aluminum alloys. Lightweight, impact resistance. VCCM must ensure uniform mechanical properties across the plate.

4. Wire Applications

Wire manufacturing is a typical VCCM application, particularly for high-value-added precious metals and semiconductor materials.²

• Electronics Sector: Chip bonding wires, circuit board leads, requiring gold/silver/copper. Ultra-fine diameter ($\le 0.05 \text{ mm}$), high conductivity. The high-purity, pore-free castings produced by VCCM are ideal raw materials for high-quality bonded wire.²

• Textile Machinery: Textile needles, embroidery thread cores, requiring stainless steel. High toughness, wear resistance. VCCM must enhance the wire’s tensile strength and surface hardness.

• New Energy: Battery tab connector wires, requiring copper/aluminum. Low resistance, corrosion resistance. VCCM must minimize internal impurities and pores in the wire.