PCD cutting tool is one of the categories of diamond tools and is widely used in metal cutting. PCD cutting tools have good performance indicators, so they have quick heat transfer, significantly reduce cutting force, low thermal deformation, high processing accuracy, and the chips are not easy to adhere to the tool tip to form mechanical tumors during the machining process.
However, as a tool, PCD cutting tools will still wear out. Let's analyze it in detail.
In the processed material, there are often some micro-particles with extremely high hardness that can scratch grooves on the tool surface, which is abrasive wear. Abrasive wear exists on all surfaces, especially on the front surface.
Abrasive wear will occur at various cutting speeds, but for low-speed cutting, other reasons for wear are not obvious due to the low cutting temperature, so abrasive wear is the main reason.
During cutting, there is a lot of pressure and strong friction between the workpiece, cutting, and the front and back surfaces, which will cause cold welding.
Due to the relative movement between the friction pairs, cold welding will cause fractures, which will cause cold welding wear. Cold welding wear is generally severe at medium cutting speeds.
Experiments have shown that brittle metals have stronger resistance to cold welding than plastic metals; multiphase metals have smaller cold welding tendencies than single-phase metals; metallic compounds have smaller cold welding tendencies than elemental metals; and B-group elements in the periodic table of chemical elements have smaller cold welding tendencies with iron. Cold welding is more severe for high-speed steel and cemented carbide at low cutting speeds.
During high-temperature cutting, in the process of contact between the workpiece and the tool, the chemical elements of both sides will mutually diffuse in the solid state, changing the composition and structure of the tool surface and making it brittle, which aggravates the wear of the tool. The diffusion phenomenon always maintains a high-depth gradient object diffusing continuously towards a low-depth gradient object.
When the temperature rises, the surface of the tool oxidizes to produce relatively soft oxide, which is worn due to friction with the chips, called oxidation wear.
For example, at 700℃ to 800℃, the oxygen in the air reacts with cobalt and carbides and titanium carbide in cemented carbide to form relatively soft oxides; at 1,000℃, PCBN undergoes a chemical reaction with water vapor.
In short, whether it is PCD cutting tools or other tools, abrasive wear, cold welding wear, diffusion wear, and oxidation wear are the main reasons for tool wear. We also hope that this can help everyone better understand PCD cutting tools.
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