Chemical Affinity of Tool Material with Iron

Diamond cutting tools are typically made of a material that has a high hardness and is chemically inert, such as polycrystalline diamond (PCD). While these properties make diamond cutting tools ideal for machining non-ferrous materials like aluminum, they are not recommended for use on ferrous metals like iron.

The main reason for this is the chemical affinity between diamond and iron. Iron has a high affinity for carbon, which is the primary element in diamond. When diamond cutting tools are used on ferrous metals, the high temperatures generated during machining can cause the iron to react with the carbon in the diamond, resulting in the formation of iron carbide.

Iron carbide is a hard, brittle material that can quickly wear down the cutting edge of a diamond tool. This can lead to premature tool failure and poor machining performance. In addition, the formation of iron carbide on the cutting edge of the tool can also cause surface finish issues on the workpiece.

Other Factors

While chemical affinity is the primary reason why diamond cutting tools are not recommended for ferrous metals, there are other factors that also come into play. These include:

- High thermal conductivity of work material: Ferrous metals like iron have a high thermal conductivity, which means they can quickly dissipate heat generated during machining. This can make it difficult to maintain the high temperatures required to properly cut with a diamond tool.

- Poor tool toughness: Diamond is a very hard material, but it is also brittle. This means that it can easily chip or fracture when subjected to high forces or impacts. Ferrous metals can be difficult to machine, and the high forces involved can make diamond tools more prone to failure.

Conclusion

In summary, diamond cutting tools are not recommended for machining ferrous metals like iron due to the chemical affinity between diamond and iron. This can lead to premature tool failure and poor machining performance. While other factors like high thermal conductivity and poor tool toughness can also be issues, the chemical affinity is the primary reason why diamond tools are not recommended for ferrous metals.