What is a characteristic of milling machines?

Milling machines represent a versatile segment of machining technology, and a defining characteristic is their operational flexibility. They can indeed be operated both manually, where a skilled machinist controls the machine's movements, and through Computer Numerical Control (CNC), allowing for automated, precise, and repeatable machining processes. This adaptability enhances their efficiency and suitability for a wide range of applications, from simple tasks to complex operations.

The ability to operate in either mode is significant for industries that require both short-run custom machining and long-run production where efficiency is paramount. This versatility allows operators to choose the best method based on specific project requirements or available technology.

In contrast, the other options do not accurately convey the range of capabilities associated with milling machines. They are not limited to manual operation alone, can perform multiple operations (such as drilling, boring, and surface cutting), and are not restricted to only single-point tools; they typically utilize various tools, including end mills and face mills, which can handle a range of machining tasks.