CNC Machining: The Difference Between Cast Iron and Steel(electric discharge machine Cornell)

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In the world of manufacturing, CNC (Computer Numerical Control) machining has become an indispensable process. It allows for precise and efficient production of various parts and components used across numerous industries. Today, we will delve into the differences between cast iron and steel in relation to CNC machining.

1. Understanding Cast Iron:
Cast iron is a popular material known for its excellent heat retention and durability. It is essentially an alloy of iron containing carbon, silicon, and traces of other elements. This combination gives cast iron its distinctive properties, making it suitable for a wide range of applications.

a) Producing Cast Iron:
To produce cast iron through CNC machining, manufacturers typically start by melting scrap iron or pig iron in a furnace at extremely high temperatures. Once melted, the molten iron is poured into molds to give it the desired shape. After solidification, the cast iron undergoes further processing such as sanding, grinding, and polishing to achieve the desired finish.

2. Exploring Steel:
Steel, on the other hand, is an alloy made primarily from iron and carbon. Unlike cast iron, steel offers greater malleability, strength, and versatility. It comes in various forms such as stainless steel, mild steel, and tool steel, each possessing distinct properties.

a) Manufacturing Steel:
The process of producing steel involves melting raw materials like iron ore, coal, and limestone in a blast furnace. Through controlled heating and mixing, impurities are removed, resulting in molten steel. Depending on the intended application, the molten steel can be shaped into various products using CNC machining techniques.

3. Comparing Properties:
While both cast iron and steel have their respective strengths, understanding their key differences is crucial for selecting the appropriate material for specific applications.

a) Strength and Weight:
Steel is generally stronger than cast iron due to its higher tensile strength. It can withstand heavy loads and is commonly used in applications where durability is of utmost importance. On the other hand, cast iron offers excellent compression strength, making it suitable for objects that bear weight.

b) Machinability:
In terms of CNC machining, steel is easier to work with when compared to cast iron. Steel parts can be cut, drilled, and shaped more efficiently due to its malleability. Cast iron, however, poses challenges due to its hardness and brittleness, requiring specialized cutting tools and techniques.

c) Heat Resistance:
One of cast iron's notable characteristics is its exceptional heat retention capabilities. It retains heat for longer periods, making it ideal for applications involving high temperatures, such as engine blocks or cookware. While steel also exhibits good heat resistance, it may require additional coatings or treatments in certain applications.

d) Corrosion Resistance:
Stainless steel, a variant of steel, stands out for its corrosion-resistant properties. It contains chromium, which forms a passive oxide layer on its surface, protecting it from rusting and other forms of corrosion. In contrast, standard cast iron is vulnerable to oxidation and requires regular maintenance to prevent rusting.

4. Applications:

a) Uses of Cast Iron:
Cast iron finds extensive use in industries that rely on its remarkable ability to withstand intense heat and serve as an effective thermal conductor. From engine blocks and pipes to stovetop cookware, cast iron's heat preservation qualities are highly valued.

b) Applications of Steel:
The versatility of steel allows it to be applied across numerous sectors. Its strength makes it perfect for structural engineering purposes like building frames, bridges, and machinery components. Additionally, stainless steel's corrosion resistance enables its use in medical devices, kitchen appliances, and automotive parts.


Understanding the difference between cast iron and steel is vital for successful CNC machining processes. While both materials have their unique characteristics, steel's strength, machinability, and corrosion resistance often make it the preferred choice. Nonetheless, cast iron's heat retention and compressive strength ensure its relevance in specific applications. By considering these factors, manufacturers can optimize CNC machining to produce high-quality parts suitable for any project or industry. CNC Milling