... , Drilling holes, Tapping, CNC Machining and Assembly.5. Surface treatment: Sandblasting, Tumbling, Powder coating, Wet painting, Chromating(chemical film) and Polishing ... , Drilling holes, Tapping, CNC Machining and Assembly.5. Surface treatment: Sandblasting, Tumbling, Powder coating, Wet painting, Chromating(chemical film) and Polishing ...