Electric motor driven hydraulic clamping systems are commonly employed in Computer Numerically Control (CNC) machine tools for fixing work pieces on the machine table. The flow requirements for a typical hydraulic clamping system varies during machining of components, however, the existing electric motor drives operates at the constant speed and it leads to increased electrical power consumption. This paper presents an energy conservation strategy by retrofitting a variable frequency drive (VFD) in the motor drive of the hydraulic clamping system in a CNC machine for varying the speed of the motor at different load conditions and minimizing the power consumption of an electric motor. Flow characteristics and electric power consumption of proposed VFD based hydraulic pumping system was compared with the existing hydraulic pumping circuit and the results were presented. It was found that the proposed hydraulic pumping system operates at low follow rate after implementation of VFD and it consumes less power compared to existing hydraulic clamping system. © 2017 Elsevier Ltd.