Key points for quality selection of aluminum rod DC casting crystallizer

1. Base material (core)

Priority should be given to forging deformed aluminum alloy substrates, and casting aluminum alloy billets is prohibited. The forged material should be dense and free of loose pores, resistant to thermal alternating deformation, and not easily swollen or deformed by long-term high-temperature water cooling. Copper crystallizers have better thermal conductivity, but higher costs; Most anodizing crystallizers on the market are made of forged aluminum substrates.

Simple identification: The manufacturer is required to provide a material warranty certificate, and the substrate must not have sand holes, pores, or cracks.

2. Quality of hard anodized layer (key focus of anodized version)
2.1 Must have hard anodizing, not ordinary decorative anodizing; The recommended film thickness is 45-70 μ m, with high film hardness, resistance to high-temperature aluminum liquid erosion, and resistance to scale corrosion. The pores can store oil and gas lubricating media, reducing aluminum adhesion and rod pulling defects.

2.2 The film layer is uniform, without local whitening, peeling, or pinholes; The roughness of the inner wall working surface should be low to ensure a smooth surface of the aluminum rod.

Pitfalls: Low priced products with thin oxide layers can cause peeling and corrosion after dozens of furnaces, resulting in scratches and cold insulation on the bars.

3. Inner cavity machining accuracy and taper
3.1 High precision of internal roundness and coaxiality, with strict dimensional tolerances; **Reasonable inner cavity taper is key, compensating for thermal expansion and preventing rod jamming and scratching of the casting rod surface.

3.2 The installation groove of the graphite ring is processed smoothly, and there is no step misalignment after assembly; Misalignment can directly cause scratches and scars on the surface of the aluminum rod.

4. Water cooling chamber/water jacket structure and sealing
4.1 The cooling water channels are evenly distributed, and the spray holes are arranged neatly to ensure consistent circumferential cooling intensity; Uneven cooling can lead to cracks, bamboo knots, and segregation nodules in the rod material.

4.2 The weld seam of the water chamber is full and free of virtual welding. It must undergo a water pressure test before leaving the factory to prevent water leakage and seepage; The sealing groove is processed properly and matched with a heat-resistant silicone rubber sealing ring, which can withstand repeated heating and cooling without leakage.

Practical acceptance: The manufacturer is required to provide water pressure test records before leaving the factory.

5. Quality of graphite ring matching
Graphite rings are vulnerable parts, but they directly affect the finished product: high-purity fine particle graphite is selected, which has good self-lubricating properties and high thermal stability; Poor quality graphite with insufficient density is prone to slagging and edge breakage, causing slag inclusion and scratches on the surface of aluminum bars.

6. Adaptation to working conditions and measured results
6.1 Clear distinction between hot top and ordinary crystallizer, matching your casting rod diameter, casting speed, and alloy series (6 series/7 series have different requirements for crystallizer cooling and taper).

6.2 Machine reference to judge the quality of the crystallizer: A good crystallizer produces aluminum rods with a smooth surface, less cold insulation, tensile cracking, and bamboo joints; Under hot conditions, the deformation of the crystallizer body is minimal and its lifespan is long.

7. Factory verification data
Request: substrate material report, hard oxide film thickness testing report, water pressure test record; Don't just look at the appearance.