CNC Machining: Unveiling the Difference between Cast Iron and Steel(thermosets vs thermoplastics Genevieve)

  • Time:
  • Click:17
  • source:PERFSO CNC Machining


CNC machining is an innovative manufacturing process that utilizes computer numerical control (CNC) systems to automate and precisely control various machining operations. This advanced technology has revolutionized the production of parts and components across industries, offering higher accuracy, increased efficiency, and improved productivity.

In CNC machining, materials play a crucial role in determining the quality, strength, and functionality of the end product. Two widely used materials are cast iron and steel. While both offer remarkable properties, they differ significantly in composition, characteristics, and applications. In this article, we will delve into these dissimilarities to help you understand the difference between cast iron and steel in CNC machining.

1. Composition:

Cast Iron:
Cast iron is an alloy primarily composed of iron, carbon, and silicon. It also contains small amounts of other elements such as sulfur, manganese, and phosphorus. The high carbon content distinguishes cast iron from other forms of iron.

Steel is an alloy that mainly consists of iron and carbon, with carbon content typically ranging from 0.2% to 2.1%. Alloying elements like chromium, nickel, molybdenum, and others can be added to enhance specific properties.

2. Characteristics:

Cast Iron:
Cast iron possesses excellent wear resistance, good machinability, and impressive casting properties. It exhibits high compressive strength, making it suitable for applications involving heavy loads or pressure. Cast iron also has good damping capabilities, reducing vibrations and absorbing shocks. However, it lacks ductility and has poor tensile strength, making it prone to breakage under tension.

Steel is renowned for its superior mechanical properties, including high tensile strength, toughness, and ductility. It maintains its structural integrity even under extreme conditions, displaying exceptional resistance to deformation, bending, and fatigue. Steel's versatility allows it to be easily welded, machined, and formed into various shapes. Additionally, it offers excellent heat resistance, making it suitable for applications subjected to high temperatures.

3. Applications:

Cast Iron:
Cast iron finds extensive usage in CNC machining due to its wear resistance and ability to withstand extreme operating conditions. It is commonly employed in the manufacturing of engine blocks, pipes, automotive parts, cookware, and machine tool structures. The use of cast iron ensures durability and stability in heavy-duty machinery.

Steel's wide range of properties makes it highly versatile and applicable in numerous industries. From construction and infrastructure to automobile and aerospace sectors, steel plays a vital role. In CNC machining, steel is used to produce components where strength, hardness, and toughness are crucial. This includes gears, shafts, bearings, structural frames, cutting tools, and more.

4. Machining Considerations:

Cast Iron:
When machining cast iron, certain factors need to be considered. Cast iron tends to transfer heat slowly, causing thermal deformation during machining. Adequate cooling measures must be in place to minimize this effect. Moreover, a slower cutting speed and the use of sharp cutting tools are recommended to prevent excessive tool wear. Cast iron can also generate graphite dust during machining, which requires proper ventilation or filtration systems.

Machining steel demands specific considerations as well. As steel has higher tensile strength and hardness compared to cast iron, greater cutting forces may be required. A higher cutting speed can improve efficiency but must be carefully optimized based on the specific alloy and application to avoid issues such as overheating or premature tool failure.


In summary, while both cast iron and steel offer distinct advantages in CNC machining, they differ significantly in composition, characteristics, and applicability. Cast iron exhibits superior wear resistance, damping capabilities, and casting properties, making it ideal for heavy-load applications. On the other hand, steel showcases excellent mechanical properties, heat resistance, and versatility, allowing it to be used in numerous industries.

Understanding these differences is crucial for manufacturers and CNC machining professionals. By selecting the appropriate material based on the required properties and applications, efficient and effective production can be achieved, resulting in robust, reliable, and high-quality components. CNC Milling