PURPOSE: To improve copper rod quality, roll life and performance by controlling an oil-water emulsion used for cooling and lubricating rolls by using a conductivity probe.

CONSTITUTION: The production of a copper rod by rolling copper may be improved by effectively controlling the water-soluble emulsion used for lubricating the rolls by using the conductivity probe for maintaining the conductivity of the emulsion within a desired operation limit. The conductivity measurement is substantially unaffected by the pollutant accumulating in the emulsion under process conditions or at the time of rolling operation and the maintenance of the conductivity only within the set limit increases the effectiveness of using the water-soluble oil, thereby creating the enhanced efficient and cost effective rolling operation. A sample is periodically sampled from the emulsion and the conductivity thereof may be easily measured by a conductivity meter. Since the lesser replenishing oil is used, the saving of a cost and the improvement in the roll life are possible.