In an industrial setting, CNC machines can be combined into entire cells of tooling machines that can operate independently of each other. They are often driven by completely digital designs, which eliminates the need for design blueprints to be physically drawn up. Many are capable of running for several days without human intervention. In fact, some are so sophisticated that they can contact the operator`s cell phone and send an alert if a malfunction occurs. These automated features make it possible to produce thousands of parts with minimal supervision, and free the operator to perform other tasks. Besides this, a CNC machine can form parts with a level of precision that is nearly impossible using older tools. In a conventional factory, workers must control different tools by hand, and errors are common, but a machine can perform the same task without becoming tired, and can work non-stop. This saves a lot of time, and the improved accuracy can help eliminate waste, since there are less faulty parts that have to be thrown away. Despite their advantages, CNC machines are more expensive than older types of machines, which can make them unaffordable for smaller operations. They're also expensive to repair and maintain. Also, though they do limit the potential for errors, they don't eliminate it entirely, since operations can still program or operate the machine incorrectly. Additionally, these machines need to be operated by a skilled workforce with a specific type of training, which may not be available in all areas.