Understanding the Distinctions between Cast Iron and Steel in CNC Machining(low pressure casting Andrew)

  • Time:
  • Click:9
  • source:ESKRIDGE CNC Machining


In the world of manufacturing, different materials play crucial roles in various processes. Two commonly used materials are cast iron and steel, which both find extensive applications in CNC (Computer Numerical Control) machining. While these metals may seem similar at first glance, it is important to understand their distinctions to ensure optimal results for specific projects. This article aims to explore the differences between cast iron and steel in the context of CNC machining.

What is CNC Machining?

CNC machining refers to a method of manufacturing that utilizes computer-controlled machines to produce highly accurate and precise parts from solid blocks or bars of raw material. The process involves removing excess material using specialized tools like drills, lathes, or mills, ultimately resulting in a finished component meeting exact specifications.

Understanding Cast Iron:

Cast iron is an alloy primarily consisting of iron, carbon, and small amounts of silicon. It derives its name from the casting process involved in its production. Molten iron is poured into molds and allowed to cool down, leading to the formation of cast iron components with excellent hardness and wear resistance.

When CNC machining cast iron, one must consider some key characteristics. Firstly, cast iron tends to be brittle compared to steel due to the presence of graphite flakes in its microstructure. Consequently, sharp cutting tools should be used to reduce potential chipping. Secondly, cast iron exhibits impressive damping capabilities, making it ideal for noise reduction and vibration absorption. Lastly, this material boasts excellent thermal conductivity, ensuring effective heat dissipation during machining operations.

Exploring Steel in CNC Machining:

Unlike cast iron, steel is an alloy made mainly by adding carbon to iron. By manipulating the carbon content and incorporating other elements such as manganese, chromium, and nickel, manufacturers can create a variety of steel grades tailored to specific applications. These grades vary in terms of strength, hardness, ductility, and corrosion resistance.

Steel's versatility in CNC machining lies in its wide range of available options. For instance, high carbon steels are ideal for cutting tools due to their exceptional hardness, while stainless steels offer excellent resistance against rusting and corrosion. Furthermore, low carbon steels are relatively easy to machine and form, making them suitable for various applications.

Differences between Cast Iron and Steel:

1. Hardness:
Cast iron generally offers higher hardness than steel due to the presence of graphite flakes. This attribute makes cast iron less machinable, requiring sharper tools during CNC processes.

2. Strength:
Steel is known for its superior strength compared to cast iron. Depending on the grade, steel can provide outstanding tensile and yield strength, allowing for more robust components when CNC machining.

3. Ductility:
While ductility refers to a material's ability to deform plastically before fracturing, cast iron exhibits lower ductility compared to many steel grades. Consequently, steel may be preferred in applications where flexibility and malleability are crucial factors.

4. Corrosion Resistance:
Stainless steel grades offer exceptional corrosion resistance, protecting finished parts from rust and degradation. Cast iron, however, is prone to oxidation and requires additional protective coatings or treatments to enhance its resistance capabilities.

5. Cost:
In general, cast iron tends to be more cost-effective than most steel grades. However, the overall costs depend on specific requirements, such as part complexity, volume, and required finishing operations.


In the realm of CNC machining, understanding the differences between cast iron and steel is essential for selecting the optimal material for a given project. Cast iron brings remarkable hardness, damping properties, and heat dissipation abilities, while steel offers higher strength, increased ductility, and corrosion-resistant options. Each material has its advantages and considerations, depending on the desired outcome.

By choosing the appropriate material based on the project's specifications, manufacturers and engineers can ensure efficient CNC machining processes, resulting in high-quality, reliable components. CNC Milling CNC Machining