This paper presents the results of calculation and numerical simulation to improve the bearing film stiffness of the medium cylindrical grinding machines with a reasonable hydrostatic parameters. | Journal of Science & Technology 130 (2018) 017-023 Study to Improve the Spindle Bearing Stiffness of Medium External Cylindrical Grinding Machines Based on Numerical Simulation of Hydrostatic Lubrication Van-Hung Pham*, Tuan-Anh Bui, Thuy-Duong Nguyen Hanoi University of Science and Technology, No. 1, Dai Co Viet, Hai Ba Trung, Hanoi, Viet Nam Received: March 27, 2018; Accepted: November 26, 2018 Abstract Medium-sized cylindrical grinding machines are fine-machining machine tools, which are widely used in the manufacturing industry. Accuracy of grinding process depends mainly on the precision and working quality of the spindle unit, in which the stiffness of the spindle bearings plays an important role. On the spindle bearings of external cylindrical grinding machine, the machine is usually uses hydrodynamic bearing with three self-aligning pad, which allows the machining workpiece to achieve a rounded and accurate diameter up to mm. Based on the hydrostatic lubrication theory as well as the current fabrication and fabrication capabilities of the self-aligning pad of hydrodynamic bearing spindle, this paper presents the results of calculation and numerical simulation to improve the bearing film stiffness of the medium cylindrical grinding machines with a reasonable hydrostatic parameters. Keywords: External cylindrical grinding machine; Spindle bearing stiffness; Hydrostatic lubrication. 1. Introduction One of the important technical requirements of external cylindrical grinding machines is the stiffness of the spindle unit. One of the important technical requirements of external cylindrical grinding machines is the stiffness of the spindle unit. The spindle unit stiffness is determined by the ratio of the force causing displacement and the displacement value of the spindle. A greater stiffness results in a higher precision level of the machine, and a higher precision machining of workpiece. Therefore, enhancement of the spindle stiffness of the external