By varying the grain size of tungsten carbide in the ra […]
By varying the grain size of tungsten carbide in the range of 1-5 μm, tool manufacturers can change the matrix properties of cemented carbide tools. The particle size of the matrix material plays an important role in cutting performance and tool life. The smaller the particle size, the better the wear resistance of the tool. Conversely, the larger the particle size, the better the toughness of the tool. Fine particle matrix is mainly used for the processing of blades of aviation grade materials such as titanium alloys, Inconel alloys and other superalloys.
In addition, a better toughness can be obtained by increasing the cobalt content of the cemented carbide tool material by 6% to 12%. Therefore, the specific machining requirements can be met by adjusting the cobalt content, whether it is toughness or wear resistance.
The performance of the tool substrate can also be enhanced by forming a cobalt-rich layer near the outer surface, or by selectively adding other alloying elements (such as titanium, tantalum, vanadium, niobium, etc.) to the cemented carbide material. The cobalt-rich layer significantly increases the strength of the cutting edge, which improves the performance of roughing and interrupted cutting tools.
When selecting the tool base that matches the workpiece material and processing method, it also considers the other five matrix properties - fracture toughness, transverse rupture strength, compressive strength, hardness and thermal shock resistance. For example, if a cemented carbide tool has a chipping along the cutting edge, a base material with a higher fracture toughness should be used. In the case of direct failure or breakage of the cutting edge of the tool, the possible solution is to use a base material with a higher transverse breaking strength or a higher compressive strength. For machining applications with high cutting temperatures (eg dry cutting), tool materials with higher hardness should generally be preferred. In the case where it is possible to observe the hot crack of the tool (the most common in milling), it is recommended to use a tool material with better thermal shock resistance.