How is the platform error measured for cast iron platforms?

(1) The principle of loop method utilizes the adjustment principle of measuring closed loops, so that the distance between the new position of each measured point after adjustment and the measurement base becomes the distance between each point relative to the ideal plane. At this point, the ideal plane is the horizontal plane passing through the origin.

(2) The principle of appropriateness is to use an ideal plane that is tangent to the actual surface, and the distance between the ideal plane and the actual surface is small, where this distance is the flatness value.

(3) The principle of the three-point method (SANDIAN) defines the ideal plane as the evaluation base plane (JIMIAN) formed by three points on the actual surface that are far apart (XIANGJU) and not on a straight line. The difference between the median and minimum deviations (XIOAZHI) of each measuring point from this plane is used as the flatness error value of the measured surface (CEBIAO).

(4) The principle of least squares is to place an ideal plane in the middle of the actual surface according to its orientation, and to make the sum of the squared intervals between each point on the actual surface and the ideal plane small. This least squares plane is used as the evaluation base, and the difference between the median and minimum deviation of each measuring point from this plane is the PINGMIAN degree error value of the measured surface plane.

(5) The diagonal principle uses a plane parallel to one diagonal of the tested surface as the evaluation base, and the difference between the median and minimum deviation of each measuring point from this plane is the flatness error value of the tested surface. (6) The small premise principle involves enclosing the actual surface with two parallel ideal planes, and making the interval between the two ideal planes small, which is the flatness error value.

(7) The principle of straightness takes the straightness error of any cross-section on the actual surface as the flatness error value.