When drawing up design plans, all manner of tolerances are specified on the drawings, yet in practice, the parts simply cannot be produced to those specifications. Is it that the design precision is too high, or that manufacturing standards are too low? How can we reconcile the drawings with the actual machining process? After reading the following, you might just get the hang of it.

Machining error is the degree of deviation between the actual geometric parameters (geometric dimensions, geometric shape and mutual position) and the ideal geometric parameters of a machined part.

机械加工误差是指零件加工后的实际几何参数（几何尺寸、几何形状和相互位置）与理想几何参数之间偏差的程度。零件加工后实际几何参数与理想几何参数之间的符合程度即为加工精度。加工误差越小