Erosion processes use air, water, or other natural forces to abrade materials. Water jet cutting belongs to this category.
The high-pressure water jet generated by water jet cutting is ejected from a small orifice, forming high-speed water flow. In pure water applications, this high-speed flow can erode the material to be cut. In abrasive water jet cutting, high-speed water makes the abrasive (usually garnet) mixed after passing through the orifice to accelerate the flow; the accelerated water abrasive mixture will erode the material to be cut. For harder materials such as metal and stone, abrasive water jet cutting is required.