1.Size accuracy
Refers to the consistent degree between the parts’ actual size after processed and the size of
the parts’ size tolerance center.The size accuracy is controlled by the size tolerance.Size
tolerance
is the allowed part size change volume of the cutting machining.In almost the same size, the
smaller the size tolerance, the higher the size accuracy.
2.Shape accuracy
Refers to the consistent degree between the actual shape of the processed parts surface and
the ideal geometry. To evaluate the shape precision of the project consist 6 items :the
straightness, flatness, roundness, cylindricity, contour. Shape accuracy is controlled by the
shape tolerance.All the shape tolerance are divided to twelve accuracy grades,except roundness
and cylindricity are divided to thirteen accuracy grade.The highest is grade one,the lowest is grade
twelve.
3.Positional accuracy
Refers to the actual location accuracy difference between the processed parts surface.
To evaluate the location precision of the project consist 8 items: the parallel degree, vertical degree,
slope, alignment, symmetry, position degrees, round beating and beating. Location tolerance is
controlled by the position tolerance .They also can be divided to twelve accuracy grade.
