Cast Iron vs. Steel: Understanding the Differences in CNC Machining(strip plating Curitis)

  • Time:
  • Click:10
  • source:ESKRIDGE CNC Machining


CNC machining, an acronym for Computer Numerical Control machining, is a manufacturing process that utilizes pre-programmed computer software to control the movement of machine tools and convert raw materials into finished products with high precision. This article aims to shed light on the key differences between two commonly used materials in CNC machining – cast iron and steel.

Cast Iron:

Cast iron is an alloy consisting primarily of iron, carbon, and silicon. It is produced by melting iron and adding small amounts of other elements such as manganese, sulfur, and phosphorus before pouring it into molds to solidify. The resulting material possesses excellent heat retention properties and exceptional wear resistance, making it suitable for applications like engine blocks, pipes, cookware, and machine tool beds.


Steel, on the other hand, is an alloy made up mainly of iron and carbon, typically containing smaller amounts of other elements such as manganese, chromium, or nickel. Its production involves refining iron ore, removing impurities through various processes, and adjusting the carbon content to achieve desired strength and durability levels. Steel exhibits high tensile strength, good ductility, corrosion resistance, and thermal conductivity, making it widely used in construction, automotive, aerospace, and machinery industries.

Differences in Composition:

One of the fundamental distinctions between cast iron and steel lies in their chemical compositions. Cast iron contains a higher carbon content (typically 2% to 4%) compared to steel's lower carbon percentage (usually below 1%). This significant disparity accounts for the dissimilar mechanical properties exhibited by these materials during CNC machining processes.

Mechanical Properties:

The higher carbon content present in cast iron contributes to its brittleness and low malleability, making it prone to cracks and fractures under excessive loads. Conversely, steel's lower carbon content provides greater flexibility, tensile strength, and resilience, allowing it to withstand heavy loads and absorb impacts better. Steel's superior malleability also enables manufacturers to shape and form it into intricate designs more easily.


CNC machinists often encounter diverse challenges when working with cast iron and steel due to their distinct machining properties. Cast iron is characterized by its high graphite content, which creates short and discontinuous chips during the machining process, leading to potential tool wear issues. Furthermore, the brittle nature of cast iron requires careful consideration of cutting speeds and feed rates to prevent chipping or breakage.

Steel, on the other hand, produces longer chips that are continuous during machining, facilitating the removal of material without severe tool wear concerns. The inherent toughness and ductility of steel allow for faster machining speeds with higher precision, reducing production time and costs while maintaining accuracy in complex part geometries.


Due to their contrasting characteristics, both materials find extensive use in CNC machining applications across various industries. Cast iron's stability and heat retention make it ideal for parts requiring durability against thermal stress, such as engine blocks, brake rotors, and machine tools. Steel, on the other hand, is utilized where strength, corrosion resistance, and versatility are paramount, including automotive components, structural supports, surgical instruments, and aerospace fittings.


In conclusion, understanding the differences between cast iron and steel plays a vital role in achieving desired outcomes in CNC machining processes. While both materials have their unique strengths and weaknesses, steel's flexibility and mechanical properties often offer an edge in terms of machinability, cost-effectiveness, and widespread application possibilities. With this knowledge, manufacturers can optimize their production processes, ensuring quality and precision in delivering end products tailored to specific customer requirements. CNC Milling CNC Machining