• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.84-91
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• 2007

The radial error motion of a machine tool cutter/spindle system is critical to the dimensional accuracy of the parts to be machined. This paper presents an investigation into spindle run-out effects on cutting mark and surface roughness. We experimented the effects of spindle run-out on surface roughness in flat-end milling by cutting AL 7075 workpiece in various cutting conditions. In order to analyze the effects of run-out on the surface roughness, the spindle's radial error motions was measured by mounting a sphere target onto the spindle as a reference. From the experimental results, it was found that spindle un-out makes a directive effects on surface roughness in flat-end milling.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.4
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• pp.121-128
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• 1996

In order to examine spindle deformation characteristics that affects the performance of dynmic cutting acuracy due to tool weight variation in a experimental spindle. thermal deformation value of operrative spindle by the axial displacement and the radial run out was measured according to the rise of spindle temperature through the laps of operation time and the change of rotational speed under the tool weight variation. A qualitative summary is as follows ; 1) The results show that the tool weight affcets the spindle temperature variation in a experimental spindle. 2) Radial run out and axial displacement was measured according to the rise of the spindle temperature and the performance of dynamic cutting accuracy was affected by the tool weight variation. 3) Axial displacement is 1.3 times larger than the radial run out in a experimental spindle conditions. 4) Axial displacement is continuously elongated when the tool weight is repeatly exchanged since the spindle themal deformaion, however, when the same tool weight is used. the displacement is still constant.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.29-36
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• 2006

Micro drilling by high-speed air bearing spindle is very useful manufacturing technology in electronic industry For the design of high speed air bearing spindle, there are considered stability of air bearing spindle, allowable load of air bearing, run out and tooling system design for micro drill's attach and remove. According to suggested details, we designed and manufactured high-speed air bearing spindle and carried out performance estimation such as run out, temperature change in running air bearing spindle, stiffness, chucking torque. Results are follows; Run out was measured under $5{\mu}m$ at air bearing spindle revolution $20,000\sim125,000rpm$. High speed air bearing spindle's temperature rose about $20^{\circ}C$ after 5 minutes from running and then was fixed. Allowable thrust load of spindle was 17kgf. Chucking torque of collet was 15kgfcm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.41-45
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• 1996

In order to realize the high-speed machining, the relative technologies for high speed machining tool and high speed machining are required now, The machining accuracy is influenced on the disturbance by the synchronized working conditions(cutting force, spindle Run-out, thermal deformation etc.) In this paper, the effect of spindle Run-out for the high speed machining is investigated. The results show that the spindle Run-out has a great influence on the machining accuracy in high speed machining.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.3
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• pp.3-7
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• 2006

For the purpose to improve and to automate designing of high-speed spindle units (SU's), we have developed the mathematical models and software to estimate SU performance characteristics, including the run-out of spindles running on ball bearings. In order to understand better the mechanics of high-speed SUs, the dynamic interaction of ball bearings and SU, and the influence of the bearing imperfections and SU's operational conditions on the run-out, we have carried out computer simulation and experimental studies. Through the study of SU's, we have found out that run-out of SU can vary drastically with variation of rpm. The influences of rotation speed and of accuracy parameters of bearings on the SU accuracy have the greatest importance. The influence of bearing preload has a secondary importance. Comparison of the results of these studies has demonstrated adequacy of the models and software developed to the real SU's.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.956-959
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• 2004

Recently the monitoring system of tool setting in high speed precision machining center is required for manufacturing products that have highly complex and small shape, high precision and high function. It is very important to reduce time to setup tool in order to improve the machining precision and the productivity and to protect the breakage of cutting tool as the shape of product is smaller and more complex. Generally, the combination of errors that geometrical clamping error of fixing tool at the spindle of machining tool and the asynchronized error of driving mechanism causes that the run-out of tool reaches to 3$^{\sim}$20 times of the thickness of cutting chip. And also the run-out is occurred by the misalignment between axis of tool shank and axis of spindle and spindle bearing in high speed rotation. Generally, high speed machining is considered when the rotating speed is more than 8,000 rpm. At that time, the life time of tool is reduced to about 50% and the roughness of machining surface is worse as the run-out is increased to 10 micron. The life time of tool could be increased by making monitoring of tool-setup easy, quick and precise in high speed machining tool. This means the consumption of tool is much more reduced. And also it reduces the manufacturing cost and increases the productivity by reducing the tool-setup time of operator. In this study, in order to establish the concept of tool-setup monitoring the measuring method of the geometrical error of tool system is studied when the spindle is stopped. And also the measuring method of run-out, dynamic error of tool system, is studied when the spindle is rotated in 8,000${\sim}$60,000 rpm. The dynamic phenomena of tool-setup are analyzed by implementing the monitoring system of rotating tool system and the non-contact measuring system of micro displacement in high speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1066-1069
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• 2004

Recently the monitoring system of tool setup in high speed precision machining tool is required for manufacturing products that have highly complex and small shape, high precision and high function. It is very important to reduce time to setup tool in order to improve the machining precision and productivity and to protect the breakage of cutting tool as the shape of product is smaller and more complex. Generally, the combination of errors that geometrical clamping error of fixing tool at the spindle of machining center and the asynchronized error of driving mechanism causes that the run-out of tool reaches to 3∼20 times of the thickness of cutting chip. And also the run-out is occurred by the misalignment between axis of tool shank and axis of spindle and spindle bearing in high speed rotation. Generally, high speed machining is considered when the rotating speed is more than 8,000 rpm. At that time, the life time of tool is reduced to about 50％ and the roughness of machining surface is worse as the run-out is increased to 10 micron. The life time of tool could be increased by making monitoring of tool-setting easy, quick and precise in high speed machining center. This means the consumption of tool is much more reduced. And also it reduces the manufacturing cost and increases the productivity by reducing the tool-setup time of operator. In this study, in order to establish the concept of tool-setting monitoring the measuring method of the geometrical error of tool system is studied when the spindle is stopped. And also the measuring method of run-out, dynamic error of tool system, is studied when the spindle is rotated in 8,000 ∼ 60,000 rpm. The dynamic phenomena of tool-setup is analyzed by implementing the monitoring system of rotating tool system and the noncontact measuring system of micro displacement in high speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1555-1558
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• 2005

In this study, we measured cylindricity and Runout of the air bearing spindle, and tested PCB(printed circuit boards) drilling with 0.4mm micro drill at 90,000rpm and 110,000rpm in order to obtain drilling hole error. Results are as follows; The air bearing spindle's Runout was not so high within $10\mu{m}$ from 20,000rpm to 80,000rpm but it grew after 80,000rpm. Drilling hole size error was 9% at 80,000rpm and 12% at 110,000rpm because of spindle's Run out. Drilled hole shape falsified more 110,000rpm than 90,000rpm.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.614-619
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• 2009

The STW(servo track writing) system which is the process of writing servo signals on disks before assembling in drives uses the spindle motor-chuck mechanism to realize low cost because the spindle motor-chuck mechanism has merit which can simultaneously write multi-disk by piling up disks in hub. Therefore, when the spindle motor-chuck mechanism of horizontal type operates in high rotation speed it is necessary to reduce the effect of RRO(repeatable run-out) and NRRO(non-repeatable run-out) to achieve the high precision accuracy of nano-meter level during the STW process. In this paper, we analyzed that the slip in assembly surfaces can be caused by the mechanical tolerance and clamping force in hub-chuck mechanism and can affect NRRO performance. We designed springs for centering and clamping considering centrifugal force by the rotation speed and assembly condition. The experimental result showed NRRO performance improves about 30 % than case of weak clamping force. The result shows that the optimal design of the spindle motor-chuck mechanism can effectively reduce the effect of NRRO and RRO in STW process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.57-60
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• 2002

The high precision spindle is essential fer mass and low cost production of aspherical glass lens. Especially, in the grinding process of micro glass lens the performance of the spindle determine the machined surface quality. For the aspheric micro glass lens grinding, we design and make a high precision spindle. We use air bearings for high speed and low motion errors of the spindle. And the driving mechanism is an air turbine to remove heat generation. In this study, we make basic performance requirements of the spindle through benchmarking. And we confirm the requirements by basic machining test. We test air consumption, static stiffness, run-out and vibration of the spindle.