• Title/Summary/Keyword: Rotational tolerance

Search Result 27, Processing Time 0.037 seconds

Rotational tolerances of a titanium abutment in the as-received condition and after screw tightening in a conical implant connection

  • Prisco, Rosario;Troiano, Giuseppe;Laino, Luigi;Zhurakivska, Khrystyna
    • The Journal of Advanced Prosthodontics
    • /
    • v.13 no.6
    • /
    • pp.343-350
    • /
    • 2021
  • PURPOSE. The success of an implant-prosthetic rehabilitation is influenced by good implant health and an excellent implant-prosthetic coupling. The stability of implant-prosthetic connection is influenced by the rotational tolerance between anti-rotational features on the implant and those on the prosthetic component. The aim of this study is to investigate the rotational tolerance of a conical connection implant system and its titanium abutment counterpart, in various conditions. MATERIAL AND METHODS. 10 preparable titanium abutments, having zero-degree angulation (MegaGen, Daegu, Korea) with an internal 5-degree conical connection, and 10 implants (MegaGen, Daegu, Korea) were used. Rotational tolerance between the connection of implant and titanium abutments was measured through the use of a tridimensional optics measuring system (Quick Scope QS250Z, Mitutoyo, Kawasaki, Japan) in the as-received condition (Time 0), after securing with a titanium screw tightening at 35 Ncm (Time 1), after tightening 4 times at 35 Ncm (Time 2), after tightening one more time at 45 Ncm (Time 3), and after tightening another 4 times at 45 Ncm (Time 4). RESULTS. The group "Time 0" had the lowest values of rotational freedom (0.22 ± 0.76 degrees), followed by the group Time 1 (0.46 ± 0.83 degrees), the group Time 2 (1.01 ± 0.20 degrees), the group Time 3 (1.30 ± 0.85 degrees), and the group Time 4 (1.49 ± 0.17 degrees). CONCLUSION. The rotational tolerance of a conical connection is low in the "as received" condition but increases with repetitive tightening and with application of a torque greater than 35 Ncm.

Machining Tolerance of Various Implant Systems and their Components (치과용 임플란트 시스템의 기계적 가공오차에 관한 연구)

  • Kim, Hyeong-Seob;Kwon, Kung-Rock;Han, Jung-Suk
    • Journal of Dental Rehabilitation and Applied Science
    • /
    • v.24 no.1
    • /
    • pp.57-65
    • /
    • 2008
  • Purpose: Misfit of implant components was very important in terms of prosthodontics. they has been linked to prosthetic complications such as screw loosening and fracture. Although there are many results about rotational freedom or machining tolerance between fixture and abutments, the data about domestic implant systems are lacking. The aim of this in vitro study was to evaluate the rotational freedom of domestic external and internal connection implant systems between their fixtures/anlaogs and abutments comparing imported systems. Materials and Methods: Rotational freedom between abutments and fixtures/analogs was investigated by using digitalized rotational angle measuring device. (1) 1 domestic external connection system(Neobiotec) and 2 imported external connection systems(Nobel Biocare, Anthorgyr), (2) 1 domestic internal connection system(Dentium) and 4 imported external connection systems(Nobel Biocare, Anthorgyr, Straumann, Frident Dentsply), and (3) 1 domestic zirconia external connection abutment(ZirAce) were evaluated. Each group has 3 samples. Mean values for each group were analyzed. Results: The differences relative to rotational freedom between domestic and imported implant systems were observed but domestic external connection implant system showed about 2.67 degrees(in case of fixture) and internal connection system showed about 4.3 degrees(in case of fixture). Domestic zirconia abutment showed less than 3 degrees of rotational freedom in a situation where the abutment was connected to an implant fixture egardless of domestic or imported systems. Conclusion: Newly developed digitalized rotational angle measuring device has high measuring resolution. The rotational freedom of domestic implant systems were similar to imported implant systems.

Design Tolerance of High Speed Spindle considering the Variation of Ball Contact Angle in the Angular Contact Ball Bearings (고속 주축베어링의 볼 접촉각 변동을 고려한 주축 설계공차)

  • Lee, Chan-Hong
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.19 no.5
    • /
    • pp.609-615
    • /
    • 2010
  • Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.

Usefulness of 3D Rotational Angiography for Cerebral Vascular Diameter Measurement (뇌혈관 직경측정을 위한 3차원 회전 혈관조영술의 유용성)

  • Seung-Gi, Kim;Sang-Hyun, Kim
    • Journal of radiological science and technology
    • /
    • v.46 no.1
    • /
    • pp.9-14
    • /
    • 2023
  • When measuring cerebrovascular with 3D rotational angiography, the accuracy was verified by comparing the actual size and measurement size, respectively. It is intended to help select therapeutic materials and instruments during cerebrovascular intervention by comparing the average error rates for measured values in the 3DRA and CTA methods by examining with protocols such as brain CTA, which are always performed in emergency situations. The mean error rate between the groups of measurers was ±3.655% for radiation technologist and ±3.331% for university students, and the mean error rate of the student group was within tolerance (±10%), and the independent sample T-test result t =0.879, p=0.394 (p>0.05) showed no statistically difference between the two. In addition, the average error rate measured by both groups by 3DRA was measured below ±5% within the tolerance error rate (±10%), and most of CTA was measured within the tolerance range (±10%), but showed an average error rate of up to 5.65%, and the independent sample T-test result was statistically more accurate than 3DRA. Both the 3DRA method and the brain CTA method for measuring cerebrovascular size could be accurately measured within tolerance, but it would be better to measure cerebrovascular blood vessels using a more accurate 3DRA method during cerebrovascular intervention.

Prediction of Dynamic Characteristics of Rubber Mount far Anti-Vibration Considering the Dimensional Tolerance (치수공차가 고려된 방진마운트의 동특성 예측)

  • 김국원;김남웅
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2002.05a
    • /
    • pp.829-832
    • /
    • 2002
  • With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and leaved out of consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-vibration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

  • PDF

A Study on the Design of Rubber Mount for Anti-vibration of an Optical Disk Drive Considering the Dimensional Tolerance (치수공차가 고려된 광디스크 드라이브의 방진마운트 설계에 관한 연구)

  • 김국원;김남웅
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.12 no.9
    • /
    • pp.661-667
    • /
    • 2002
  • With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and loaned out consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-nitration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

A Study on the Contact Interval in the Main Spindle Interface of High Speed Spindle according to Variation of Clamping Force and Rotational Speed (고속 주축에서 클램핑력 및 회전수 변화에 따른 주축 인터페이스 접촉률 변화에 관한 연구)

  • Hwang Y.K.;Cho Y.D.;Lee C.M.;Chung W.J
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2005.06a
    • /
    • pp.1749-1752
    • /
    • 2005
  • High speed machining has become the main issue of metal cutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evaluation of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

  • PDF

A Study on the Contact Interval in the Main Spindle Interface of High Speed Spindle according to Variation of Clamping Force and Rotational Speed (1) (고속 주축에서 클램핑력 및 회전수 변화에 따른 주축 인터페이스 접촉률 변화에 관한 연구 (1))

  • Hwang Young-Kug;Chung Won-Jee;Lee Choon-Man
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.23 no.3 s.180
    • /
    • pp.147-155
    • /
    • 2006
  • High speed machining has become the main issue of metal rutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evolution of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

고속 주축의 열변형이 소음특성에 미치는 영향

  • 이찬흥;김태형;이후상
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1997.04a
    • /
    • pp.307-311
    • /
    • 1997
  • This paper describes influence of thermal deformation on nosic characteristics in high speed spindle systems. Heat generation in front, rear spindle bearings and built in motor lead to diverse thermal deformation of headstock with time. This deformation changes assemble tolerance in bearing housing, especially to elliptic form. The elliptic assemble tolerance generate high nosie level with dominant amplitude in double rotational frequency.