Cutting edge and Workpiece
In the animation to the right you can see the relationship of the cutting edge and the workpiece while machining.
At the point of contact, the workpiece and the cutting edge impact with one another and as a result the metal is removed. The metal strips removed are called "chips" or "swarf".
When machining metals, the cutting edge is subjected to severe impact and extremely high temperatures. The faster the workpiece and cutting edge impact and rub with each other, the higher the temperature. Generally, the cutting edge can reach up to temperatures of 800°C.
Cutting tools need to be able to withstand the impact and temperatures encountered when machining without sacrifcing hardness. Because of this, materials like "high-speed steels" and "cemented carbides" have been widely used. Nowadays, the "cemented carbides" are the mainstream.