The errors which affect the processing tolerance of a machine tool are due to the built-in volumetric errors in the machine tool structure and also the thermal displacement of the machine tools during its cutting. In this paper, a dualdisplacement meter compensation system is developed. The new model has a better tolerance control than the singledisplacement compensation meter method; also, it has a great potential for saving a machine's warm-up time as well as enhancing productivity. A dual-displacement meter is designed to detect the variation of spindle thermal growth and a differential amplifier is applied which ensure a precise output signal tolerance of spindle thermal growth. The unstable signal which is an effect of flatness tolerance of spindle surface is then omitted. Finally, the spindle thermal growth compensations are successfully reduced. It meets the requirement of high-speed machining and high-precision machining application.

Angular contact bearings are the most popular type of bearings used in the motorized high speed spindle. An initial preload and operating-induced load control are managed to ensure its rigidity, but the centrifugal force and temperature will rise with the rapid increase of spindle speed. Although the centrifugal force and thermo induced bearings load are applied on the spindle assembly. This paper aims to study innovative structure solution of spindle and develop a new type of super precision bearings which will ensure the lifetime and high performance of spindle. Section II proposed an improved inverter output filter, for pulsewidth modulated (PWM) drive system. The proposed filter is shown to effectively reduce the power losses in the spindle. This usage of the filter can improve lifetime of bearings and gain a higher output power of the spindle. The simulations show a 20 KW, 400 Hz PWM drive system with total loss reduced 13.36%, and a 20KW, 800HZ PWM drive system with total loss reduced 15.77%. Therefore, the filter configuration is an excellent contribution for PWM drive system.

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A dual displacement measurement meter applied as a compensatory device for spindle thermal growth compensation , it can reduce the measurement error dramatically from single measurement device. The result matches the laser inspection report, which is an external direct checking device and been considered as one of the best checking device of spindle thermal growth. However, the non-flat surface of spindle nose, fluctuating measurement distance and the tiny measurement meter can hardly be fitted rectangular to spindle nose surface which create a certain percentage of error when the single displacement measurement meter is applied.The addition of a differential amplifier will greatly enhance the linear output voltage fed back from dual measurement meter to the CPU and provide a high sensitive level of compensation. This new device can reduce the measurement error from 6% down to 1.8%. The machining tolerance can be improved greatly and machining time is reduced. The quality of the machine and the cutting performance can be upgraded.

Ram-Quill combination spindle has been applied widely in Horizontal Boring Milling Machine. It is a great benefit that the machine can be used for various applications. But as the report of experiment, the ram housing bent when it is moved for more than half of its maximum travel. The straightness of Ram housing is out of the tolerance and the run-out of the spindle is way behind the requirement when spindle is at the maximum extension point. This paper proposes an electro-hydraulic monitoring and compensation system which will be able to adjust the pressure to the mechanism in time. The experiments prove that the straightness of horizontal surface can meet the requirement, and a ball bar test at the extremely weak point shows an improvement of the roundness tolerance for 15%. This can make the machine becoming superior equipment for high precision machining.