Machining accuracy is the actual size, shape, position of the surface of the machined part and the degree of conformity of the ideal geometric parameters required by the drawing! Ideal geometric parameters, in terms of size, is the average size; in terms of shape, is the absolute circle, cylinder, plane, taper and straight line, etc.; in terms of mutual position, is the absolute parallel, perpendicular, coaxial, symmetrical, etc..

1. Dimensional Accuracy
After processing the actual size of the part and the size of the part tolerance zone centre of the degree of conformity.

2. Shape Accuracy
Refers to the actual geometric shape of the surface of the processed parts and the ideal geometric shape of the degree of conformity.

3. Positional Accuracy
Refers to the actual positional accuracy difference between the relevant surfaces of the machined part.

4. Interrelationship
Usually in the design of machine parts and parts machining accuracy, should pay attention to the shape error control in the position tolerance, position error should be less than the size tolerance. That is, precision parts or parts of the important surface, its shape accuracy requirements should be higher than the positional accuracy requirements, positional accuracy requirements should be higher than the size accuracy requirements.