A Study of Reliability Improvement of High Capacity Cooling System for Machine Tool

A machine tool is the basis and fundamental equipment of the machinery industry. A machine tool performed the machining and cutting operation over a high-speed rotation of 10,000 rpm. The cooling system plays a role of cooling the high-temperature hydraulic oil in the machine tool. Control of hydraulic oil has deep relationship with productivity and accuracy of the machine tool. In addition, the performance of control accuracy of hydraulic oil, overload cooling operation, and cooling capability are great influence on the reliability of components and whole system because it relates to operation life of the machine tool. In this paper, we draw up governing equations which are composed by combination of electric theories and empirical knowledge. And failure analysis documents such as FMMA(Failure Modes and Mechanisms Analysis), FMECA(Failure Modes, Effects, and Criticality Analysis), and FTA(Fault Tree Analysis) are drew up, to confirm the main failure modes of cooling system, and test items are determined through the QFD(Quality Function Deployment) to evaluate the reliability of prototype. Finally we have proven the propriety of the governing equations by performance test using the cooling system prototype.