The painting modification job for an automatic coating equipment can be performed by using a robot arm. Manual modification of painting not only requires high cost, but also is difficult to control quality consistency. The use of robot arm in automatic coating provides greater flexibility and working capacity than manual operation. It is capable of performing painting according to the workpiece profile with maximum flexibility. Another feature for robot painting is uniform film thickness. The paint delivery hose in combination with stable paint flow control allow paint to uniformly adhere to each point of workpiece, which results in consistent film thickness, smoother surface and increased quality qualification percentage. Due to stable control of paint flow and the initial quality control, any problem can be found and corrected immediately for reducing defect percentage to a minimum.