No. If the speed varies, an encoder can be added to the printer to track the speed and ensure the print is perfectly formed. If the product does move at a constant speed, the line speed can be entered into the printer controller.
Undisturbed, the printers require no maintenance. If knocked, some air may be drawn into the nozzles. For the Poziflow system, this is automatically expelled. For the FreeFlow system, it can be purged using a priming tube.