Positioning accuracy refers to the accuracy of the position that can be achieved by the movement of each axis of the baby nappy machine under the control of the device. Positioning accuracy can also be understood as motion accuracy. The movement of the moving parts of the nappy production line is controlled by the machine. The accuracy of each moving part is a direct reflection of the accuracy of the processing part under the control of the program instructions. Positioning accuracy is therefore a very important test element.

1. Nappy production line positioning accuracy testing

(1) Linear motion positioning accuracy testing
Linear motion positioning accuracy is generally carried out under no-load conditions on baby nappy machines and tables. According to national standards and the International Organisation for Standardisation (ISO standards), the testing of the nappy production line should be based on laser measurements. For cases where a laser interferometer is available, the general user can also use a standard ruler and an optical reading microscope for comparative measurements. However, the accuracy of the measuring instrument must be higher than the measurement accuracy by 1~2 grades.
(2) Linear motion repeat positioning accuracy detection
The instruments used for testing are the same as those used for testing positioning accuracy. The general test method is to measure any three positions at the midpoint and both ends of each coordinate stroke. Each position is positioned by rapid movement and the positioning is repeated seven times under the same conditions to measure the stop position value and the maximum reading difference. As the repeatable positioning accuracy of a coordinate, it is the most basic indicator of the stability of the accuracy of the axis movement.

2. Nappy production line home position accuracy detection

(1) Home return accuracy testing of linear motion
Home return accuracy, essentially a special point of repeat positioning accuracy, so its detection method is exactly the same as repeat positioning accuracy.
(2) Home return accuracy inspection of rotary table
The measurement method is to return to the home position from 7 arbitrary positions, measure its stop position and use the maximum difference read out as the accuracy of the home return.
It should be noted that in the case of rapid positioning, the existing positioning accuracy check was measured. For some nappy production lines where the feed system is not very good, different values of positioning accuracy are obtained when different feed speeds are used for positioning. In addition, the semi-closed loop system currently used is related to the ambient temperature and the operating condition of the axes.

Currently, if a choice of nappy production line is allowed, it is preferable to choose one with high repeatability.