How Do Continuous Casting and Direct Casting Differ?

April 10, 2024

Continuous casting and direct casting are two distinct methods of producing metal billets, ingots, and slabs. Both have their merits. Continuous, or strand, casting is generally used for smaller cross-sectional products in a continuous process. Conversely, direct casting is typically used for profiles with larger cross-sections. Despite differences in configuration and application, both casting approaches have many of the same production concerns, such as optimising mold release and minimising corrosion. Boron nitride ceramics & coatings offer an ideal solution for these painpoints.

Continuous Casting

As the name suggests, continuous casting is characterized by the uninterrupted flow of molten metal into a mold. From there, it solidifies into a continuous length. This method is designed to mass-produce metal products with uniform cross-sections, such as beams, billets, and slabs. 

The continuous casting process begins with melting metal, which is then fed into a water-cooled mold. As the metal exits the mold, it is solid but still malleable. This allows it to be shaped into long sections without halting the casting process.

The advantages of continuous casting are manifold. It offers a high degree of automation, reducing labor costs and minimizing human error. Continuous casting is also remarkably efficient, as it allows for:

  • A steady production flow
  • The reduction of waste
  • Less energy consumption. 

Continuous casting is particularly suited for industries requiring large volumes of standard shapes. This includes construction and automotive manufacturing, where the demand for beams and slabs is perennial and voluminous. 

Direct Casting

Unlike continuous casting, direct casting is a batch process, meaning each cast is an independent production event. This method is highly versatile, allowing for the creation of complex shapes and sizes tailored to specific applications. 

Direct casting is the go-to method for producing intricate parts or those with unique material properties. Examples include specialized alloys or metals that require careful handling and precise cooling rates.

The primary advantage of direct casting lies in its flexibility. It can accommodate small production runs and is ideal for manufacturing custom or specialized products. 

Moreover, direct casting allows for a greater variety of materials and designs. It caters to industries where customization and material properties are paramount, such as:

  • Aerospace 
  • Medical device manufacturing 

However, this flexibility comes at the cost of lower efficiency and higher labor intensity compared to continuous casting. This makes it less suitable for high-volume production.

Utilize Boron Nitride With Your Casting Solutions

There are many factors needed to consider when utilizing different continuous casting and direct casting molds to create the perfect shape of your metal. The material of the cast, such as metal or ceramic materials, could affect the quality of the final product. Manufacturers must consider how the material will react to thermal expansion or whether it will be subject to flaws.

Boron nitride has proven highly effective in metal casting applications, particularly in continuous casting. Hot-pressed boron nitride ceramics have been machined into break rings, an intermediary component between a continuous casting line's hot and cool zones. This is a crucial and often overlooked area of the casting process. The break ring must allow the melt to transition to the solidification zone without sticking. It must also withstand severe temperature differentials. Failure of the break ring can be extremely costly. Thus, materials with high thermal shock resistance and low friction coefficients are ideal for this application. Machinable boron nitride ceramics excel in this arena.

 

COMBAT® Machinable Ceramics grade ZSBN has demonstrated exceptional performance for continuous casting break rings. Combining the ideal properties of hot-pressed BN with silicon carbide and zirconia’s non-reactivity and strength, ZSBN grades offer unique thermal, chemical, electrical, wear and machinability properties. This ensures reliable long service in a range of molten metal applications.

saint-gobain boron nitride zsbn break ring
boron nitride aqueous coating

 

 

CeraGlide® Boron Nitride Coatings also serve admirably for mold release applications in direct casting. Its superior chemical resistance and non-wetting properties ensure long-lasting durability in molten metal processing lines. In cases where the substrate is white, we also offer our CeraGlide AZURE™ pigmented coatings. 

 

Due to many years servicing this application, Saint-Gobain engineers can help companies work ZSBN or BN coatings into their complex operations, saving on yields, changeover time, and improving finished products’ quality.

If you would like to learn more, contact a member of the Saint-Gobain team today.