Improving the Efficiency of Die Casting Machine Hydraulic Systems with the Retrofit of Adjustable Frequency Drives

Abstract

Die casting is a common method of light metal processing which is used to produce accurately dimensioned, sharply defined metal parts. Most die casting machines in use today utilize a complex hydraulic system to perform the necessary work required for the process. The pressure and flow rate demands on the hydraulic system vary significantly throughout the cycle. Many older systems are greatly oversized so that they are able to meet the peak hydraulic demand at any point. These systems operate inefficiently because there is typically no way to limit the hydraulic capacity during periods of low demand. As a result, fluid is throttled to lower pressures and excess fluid flow is routed directly back to the system reservoir, wasting motor energy and increasing the thermal load on the cooling system. One option for improving the efficiency of older die casting machines currently in use is the retrofit of an adjustable frequency drive, or AFD. An AFD allows the speed of the pump motor to be varied, changing the pump output to suit the cycle demands. This minimizes the amount of wasted energy without affecting other process parameters. This paper will discuss the die casting process and examine the energy savings potential of retrofitting die casting machines with adjustable frequency drives.