Machining accuracy is the actual size and shape of the surface of the part after machining. The geometrical parameters of the three geometric parameters and the ideal geometric parameters required by the drawing. The machining accuracy is measured by the tolerance level. The smaller the grade value, the higher the precision. The machining error is represented by a numerical value, and the larger the value, the larger the error. High machining accuracy means that the machining error is small and vice versa.
The ideal geometric parameters, in terms of size, are the average size; for the surface geometry, it is the absolute circular cylindrical plane cone and straight line; For the mutual position between the surfaces, it is absolutely parallel. Vertical, coaxial, symmetrical, etc. The deviation of the actual geometric parameters of the part from the ideal geometric parameters is called the machining error.
The actual parameters obtained by any processing method are not absolutely accurate. From the function of the parts, as long as the machining error is within the tolerance range required by the part drawing, the machining accuracy can be achieved.