A control system for evaluating residual operating life of a machine component of a machine tool includes a sensor and a control system. The sensor is disposed on the machine tool and is configured to sense movement of the machine component. The control device is configured to calculate a length of time based on a sense signal received from the sensor and sampled at a time point right after the machine component is freshly oiled, and to enable output of an alarm when determining that the length of time thus calculated is smaller than a predetermined length.