Within the realm of high-precision machining, based on varying levels of accuracy, it is categorized into three levels: Precision machining (accuracy 3–0.3 μm, roughness 0.3–0.03 μm); ultra-precision machining (accuracy 0.3–0.03 μm, roughness 0.03–0.005 μm, or submicron machining); and nano-machining (accuracy 0.03 μm (30 nanometers) with a roughness better than 0.005 μm).
In industrialized countries, factories typically maintain a machining accuracy of 3 μm (5 μm in my country). Machining below this value is generally referred to as ordinary precision machining, while machining above this value is called high-precision machining.
