Firstly, the distance between the sensor and the nozzle should be as close as possible, so that it is easier to obtain the starting printing position of the product; secondly, the fixed direction of the nozzle should form a 90-degree angle with the production line equipment to ensure that the printed content does not skew; if the product is side-printed, the nozzle should be installed on the side, and it should form a 5°-10° angle from top to bottom to avoid ink leakage and backflow from the nozzle, which may cause other unnecessary faults.