• Title/Summary/Keyword: disk

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Study on Improvement of Thermal Performance and Durability by Disk with Holes (타공 디스크에 의한 열적 성능 및 내구성 향상 연구)

  • Han, Moon-Sik;Cho, Jae-Ung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.1
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    • pp.62-66
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    • 2011
  • In this study, the thermal performance of disk can be compared with disk and disk with holes through numerical analysis. The capacity of thermal emission on general disk becomes more than on disk with holes at the distribution of temperature at first and the magnitude of equivalent stress on general disk becomes less than on disk with holes at the distribution of stress. The capacity of thermal emission or the magnitude of thermal deformation on disk with holes becomes less than that on general disk 30 minutes later. The disk with holes is worn less and more durable than general disk. The performance of cooling and braking force at disk and pad can be improved by installing the disk with holes.

Influence of Disk Mass with regard to Frictional Characteristics of Brake Disk for Rolling Stock (디스크 질량 변화에 따른 철도차량용 제동디스크의 마찰 특성)

  • Jung, Jong Rok;Ko, Eun Sung;Lee, Hi Sung
    • Tribology and Lubricants
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    • v.30 no.4
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    • pp.240-245
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    • 2014
  • Low alloy heat resistant brake disk and sintered brake pad are applied to mechanical brake system for the speed-up of urban rapid transit. In this research, we analyzed how the frictional characteristics between brake disk and pad are influenced by the disk mass. At a high disk mass, the friction stability was the lower value as a result of the lack of tribofilm formation at the disk surface. Wear rates of friction materials showed the higher value at a low disk mass and wear rates of 10 mm and 15 mm showed the similar level. Average friction coefficient was the lower value at the 10 mm disk thickness and range of variation of average friction coefficient was also the smaller value at the 10 mm disk thickness. However, there were no significant changes in the friction coefficients under any of test conditions. Surface roughness of a disk showed the highest value at the 5 mm disk and surface roughnesses of 10 mm and 15 mm showed the similar level. As a result, friction characteristics of disk mass influenced the friction stability, as well as the wear rate of friction pad and disk, but not the friction coefficient.

Effects of Smooth and Textured Disks on Particle Generation in a Hard Disk Drive (하드디스크 드라이브에서 Smooth 디스크와 LZT 디스크가 입자 발생에 미치는 영향)

  • Lee Dae-Young;Huh Sun-Young;Kang Pil-Sun;Hwang Jungho;Cho Keung-Youn;Kang Tae-Sik
    • 정보저장시스템학회:학술대회논문집
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    • 2005.10a
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    • pp.88-95
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    • 2005
  • The head to disk spacing must be decreased to increase recording densities in hard disk drives. Recently, to decrease the head to disk spacing, smooth disk having no bumps onto the lading zone has used. In this research, we compared the number of particles generated in HDD with smooth and textured disks. We used a sampling method using a particle sampler and a CPC (condensation particle counter) to detect particles in HDD. First, we sampled and counted panicles generated with disk rotational speed and various rest times when the smooth disk and textured disks were used, then analyzed the sampled particles by SEM (scanning electron microscopy) and AES (auger electron spectroscopy). In results of measuring particles, more particles in case of LZT disk drive generated than that of the smooth disk drive in all test modes. The number of particles generated in the smooth disk was very low. The particle generation increased as the rest time increased (smooth/LZT disks) and more particles in case of LZT disk drive generated than that of the smooth disk drive. In results of analyzing particle components, Al, Ti, Si components were detected and we could not found differences between components in case of smooth/LZT disk drive.

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Effects of Smooth and Textured Disks on Particle Generation in a Hard Disk Drive (하드 디스크 드라이브에서 Smooth 디스크와 LZT 디스크가 입자 발생에 미치는 영향)

  • Lee, Dae-Young;Huh, Sun-Young;Kang, Pil-Sun;Hwang, Jung-Ho;Cho, Keung-Youn;Kang, Tae-Sik
    • Transactions of the Society of Information Storage Systems
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    • v.2 no.2
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    • pp.123-129
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    • 2006
  • The head to disk spacing must be decreased to increase recording densities in hard disk drives. Recently, to decrease the head to disk spacing, smooth disk having no bumps onto the lading zone has used. In this research, we compared the number of particles generated ill HDD with smooth and textured disks. We used a sampling method using a particle sampler and a CPC (condensation particle counter) to detect particles in HDD. First, we sampled and counted particles generated with disk rotational speed and various rest times when the smooth disk and textured disks were used, then analyzed the sampled particles by SEM (scanning electron microscopy) and AES (auger electron spectroscopy). In results of measuring particles, more particles in case of LZT disk drive generated than that of the smooth disk drive in all test modes. The number of particles generated in the smooth disk was very low. The particle generation increased as the rest time increased (smooth/LZT disks) and more particles in case of LZT disk drive generated than that of the smooth disk drive. In results of analyzing particle components, Al, Ti, Si components were detected and we could not found differences between components in case of smooth/LZT disk drive.

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DYNAMIC CHARACTERISTICS OF SPINNING DISK VIBRATION INFLUENCED BY CENTRIFUGAL AIRFLOW (광자기 기록 장치에서의 디스크 진동과 회전 공기 유동 특성에 관한 연구)

  • 김수경;송인상;손희기
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.206-210
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    • 1998
  • A study on dynamic characteristics of rotating disks in magneto optical disk drives is presented. Natural frequencies of rotating disks are investigated experimentally and numerically. The frequency response and critical speeds of the ASMO disk are discussed. The characteristics of airflow around the disk and their effects on disk vibrations are also investigated. It is found that the numerical calculation of the natural frequencies of rotating disks agrees well with the experimental results. The airflow around the disk in the cartridge affects the characteristics of the disk vibrations to reduce the modal frequencies of the disk. The experiment shows that negative vertical offsets of the disk in the cartridge possibly increase the vibration amplitudes. As being influenced by the geometry of the cartridge, the rotation of the disk causes an asymmetric airflow in the presence of window.

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Effect of Relative Humidity, Disk Acceleration, and Rest Time on Tribocharge Build-up at a Slider-Disk Interface of HDD (HDD에서 상대습도, 디스크 가속도, 정지시간이 슬라이더-디스크 인터페이스의 마찰대전 발생에 미치는 영향)

  • Hwang J.;Lee D.Y.;Lee J.;Choa S.H.
    • Tribology and Lubricants
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    • v.22 no.2
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    • pp.59-65
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    • 2006
  • In hard disk drives as the head to disk spacing continues to decrease to facilitate recording densities, slider disk interactions have become much more severe due to direct contact of head and disk surfaces in both start/stop and flying cases. The slider disk interaction in CSS (contact-start-stop) mode is an important source of particle generation and tribocharge build-up. The tribocharge build-up in the slider disk interface can cause ESD (electrostatic discharge) damage. In turn, ESD can cause severe melting damage to MR or GMR heads. The spindle speed of typical hard disk drives has increased in recent years from 5400 rpm to 15000 rpm and even higher speeds are anticipated in the near future. And the increasing disk velocity leads to increasing disk acceleration and this might affect the tribocharging phenomena of the slider/disk interface. We investigated the tribocurrent/voltage build-up generated in HDD, operating at increasing disk accelerations. In addition, we examined the effects with relative humidity conditions and rest time. We found that the tribocurrent/voltage was generated during pico-slider/disk interaction and its level was about $3\sim16pA$ and $0.1\sim0.3V$, respectively. Tribocurrent/voltage build-up was reduced with increasing disk acceleration. Higher humidity conditions $(75\sim80%)$ produced lower levels tribovoltage/current. Therefore, a higher tribocharge is expected at a lower disk acceleration and lower relative humidity condition. Rest time affected the charge build-up at the slider-disk interface. The degree of tribocharge build-up increased with increasing rest time.

Numerical Simulations for Suppressing Transverse Vibration of a very Flexible Rotating Disk using Air Bearing Concept (고속 회전 유연 디스크의 진동 저감용 공기 베어링 해석)

  • Lee Sung-ho;Rhim Yoon-chul
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.175-185
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    • 2004
  • Rotating disks are used in various machines such as data storage device, gyroscope, circular saw, etc. Transverse vibration of a rotating disk is very important for the performance of these machines. This work proposes a method to suppress transverse vibration of a very flexible rotating disk in non-contacting manner. A system considered in this study is a very flexible rotating disk with a thrust bearing pad which is located underneath the rotating disk. The pressure force generated in the gap between the rotating disk and the thrust pad pushes the rotating disk in the direction of axis of rotation while the centrifugal force and the elastic recovery force push the rotating disk in reverse direction. The balance between these forces suppresses the transverse vibration of the rotating disk. A coupled disk-fluid system is analyzed numerically. The finite element method is used to compute the pressure distribution between the thrust pad and the rotating disk while the finite difference method is used to compute the transverse vibration of a rotating disk. Results show that the transverse vibration of the rotating disk can be suppressed effectively for certain combination of air bearing and operating parameters.

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Finite Element Analysis of Thermal Behaviours of a Disk Brake in High-Speed Trains (고속 전철에서 디스크 브레이크의 열거동에 관한 유한요소해석)

  • 김청균;조승현
    • Tribology and Lubricants
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    • v.14 no.1
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    • pp.28-36
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    • 1998
  • This paper presents the thermal behaviours of a solid type disk brake for a high-speed train. The thermal behaviours of a brake disk with 50mm thickness shows good performance compared with 45mm thickness of a disk because of a high specific heat capacity. The FEM results show that the thickness of the disk with a same weight of the brake disk should be increased for a good flexibility of the contact thermal problems. Therefore, the ratio between the pad and disk in diameter may be reduced and the thickness of a disk increased.

A Study on Dynamic Performance Improvement of HDD Disk-Spindle System (HDD 디스크-스핀들 시스템의 동특성 개선에 관한 연구)

  • 좌성훈;손진승;이행수;홍민표;고정석;곽주영;조은형
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.1130-1135
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    • 2001
  • This paper investigated the dynamic performance of HDD disk-spindle system to reduce disk fluttering. Rocking frequencies of the disk-spindle system and radial NRRO are measured to escape the ball defect frequencies and to determine the relative optimal position of the disk in the motor. It was found that disk fluttering was reduced by increasing disk thickness, inserting viscoelastic material between the disk and the spacer and decreasing the gap between the disk and the base.

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Optimal Design of Disk clamp to Reduce RRO in a Hard Disk Drive (진동저감을 위한 HDD용 Disk Clamp의 최적설계)

  • 이행수;고정석;황태연;정우철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.539-542
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    • 2002
  • The role of disk clamp is to fasten disks to motor and to prevent the slip of disks during operation. This paper examined the effects of the design parameters of disk clamp - thickness, contact radius and cross-sectional shape -on the clamping force and circumferential stress distribution of disk. The large stress variation in circumferential direction results in large disk waveness and will increase repeatable run-out (RRO) finally. The disk clamp-disk-disk spacer system is modeled and the FE analysis is performed by ANSYS. The disk clamp with large contact radius shows more uniform stress distribution than the one with small contact radius and the stiffness variation around circumferential direct ion or the addition of the bending sect ion can make stress distribution uniform.

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