In one example, a method including controlling milling of a component via a milling system, the milling system including a spindle, a tool holder coupled to the spindle, the tool holder configured to receive a milling tool; and the milling tool configured to remove at least a portion of the component via milling while the milling tool is rotated by the spindle and tool holder, wherein the milling system is configured to conduct an electrical signal between the milling tool and component during milling of the component when the milling tool is not broken; monitoring the electrical signal conducted between the milling tool and component; and determining whether the milling tool is broken based on the monitored electrical signal.