• Title/Summary/Keyword: Dimensional Tolerance

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Two-Dimensional Assessment for Measurement System Analysis (측정시스템 분석을 위한 2차원 척도 평가)

  • Seo, Sun-Keun
    • Journal of Korean Society for Quality Management
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    • v.42 no.4
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    • pp.607-616
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    • 2014
  • Purpose: This paper reviews popular measurement system indices and proposes a procedure for assessing a measurement system using two parameters with intraclass correlation and a factor for process capability. Methods: Gage Repeatability and Reproducibility(GR&R), precision-to-tolerance ratio(PTR), number of distinct categories, producer's and consumer's risks are employed to assess the measurement capabilities and discuss the relationships between measurement system metrics. Results: Two-dimensional plot by two parameters is presented to assess adequacy of the measurement system and process capability. A numerical example and previously studied case study are provided for illustration. Conclusion: The procedure proposed in this paper using two-dimension parameters provides a valuable procedure and helpful guidelines to quality and production managers in assessing the capabilities of a measurement system and choosing the needed actions to be the most benefit.

The Optimum Design for Minimizing von Mises Stress of Lead Wire (리드용 와이어의 Von Mises 응력 최소화를 위한 최적설계)

  • Park, Chang Hyeong;Cho, Seong-Jin;Han, Seimg Chul;Kim, Jin Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.4
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    • pp.119-126
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    • 2017
  • High-precision wire is one of the most important components of lead production. However, no studies have been performed on the dimensional tolerance of these wires, and their capabilities have been deduced through trial and error. Therefore, PIANO, a commercial PIDO tool, was used to systematically determine the optimal parameters for stress minimization. The values obtained from the optimum design were modeled and analyzed using LS-Dyna, a finite element analysis program. Maximum stress was reduced by about 10% compared to its initial values, and the wire now satisfies dimensional tolerance ($10{\mu}m$).

A Study on the Squareness of Circular Pocket Machining of SCM415 Steel (SCM415강의 원형포켓 가공시 직각도에 관한 연구)

  • Kim, Jin-su;Choi, Chul-Woong;Shin, Mi-Jung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.7
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    • pp.42-47
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    • 2019
  • In this research, we try to study the change of squareness in the cutting process while changing cutting conditions such as feed rate and spindle rotational speed with chromium molybdenum steel (SCM415) material and TiCN, TiAlN coated end mill tool. The TiCN coating tool had the best straightness at 4,000 rpm at a feed rate of 200 mm/min. The TiAlN coating tool was best measured at 3,000 rpm at a feed rate of 200 mm/min. TiAlN coated tools had excellent dimensional tolerance when comparing the coating tool specifics.

Tolerance Accumulation Analysis of ECV by Monte Carlo Simulation (몬테칼로 시뮬레이션을 이용한 ECV의 공차누적분석)

  • Wang, Xiang;Kang, Eunji;Chang, Heeseok;Lee, Soojin;Choi, Dukjun;Guk, Musung;Hong, Taeho;Kang, Heejong;Ahn, Youngjae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.85-94
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    • 2014
  • Tolerance accumulation has serious effect on the performance of an assembled body. This paper proposes the method which analyzes tolerance accumulation using Monte Carlo Simulation. This method can predict tolerance distribution of fully assembled body using the dimensional tolerance distribution of each part to be assembled. In this analysis, it is assumed that the tolerance of each part has the nominal distribution or uniform distribution. This analysis method is applied to ECV(External Control Valve), and the accumulated tolerance of the fully assembled ECV is obtained from the analysis. The results show that initial tolerance given to each part do not meet the design requirement of ECV. Hence, the tolerances of each part are modified and the additional analysis with the modified tolerances yields the results which satisfy the design requirements of ECV.

Probabilistic Analysis of Dynamic Characteristics of Structures considering Joint Fastening and Tolerance (체결부 및 공차를 고려한 구조물의 확률기반 동적 특성 연구)

  • Won, Jun-Ho;Kwang, Kang-Jin;Choi, Joo-Ho
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.18 no.4
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    • pp.44-50
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    • 2010
  • Structural vibration is a significant problem in many multi-part or multi-component assemblies. In aircraft industry, structures are composed of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively "fasteners"). Due to these, prediction and design involving dynamic characteristics is quite complicated. However, the current state of the art does not provide an analytical tool to effectively predict structure's dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probabilistic analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners' finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probabilistic analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is employed for this. Proposed methodology offers efficiency of dynamic analysis and reality of the field as well. Simple plates joined by fasteners are taken as an example to illustrate the proposed method.

Development of Precision Inspection Technique for Aircraft Parts Having Very Thin Features on CAD/CAI Integration (CAD/CAI 통합에 기초한 박형 단면을 가지는 항공기 터빈블레이드의 정밀측정기술 개발)

  • Park, Hui-Jae;An, U-Jeong;Kim, Wang-Do
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.6
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    • pp.1743-1752
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    • 1996
  • In this paper, a precision inspection technique using CAD/CAI integration is proposed for the parts having very thin and sharp 3 dimensional curve features. The technique begings with feature reconstruction of turbine blades which have 3 dimensional combined feometry, such as splines, and thin circles. The alifnment procedures consistsb of two phases-rough and fine phases : rough phase alignment is based on the conventional 6 point5s probing on the clear cut surfacef, and fine phase alignment is based on the intial measurement on the 3 dimensional curved parts using an lterative measurement feed-back least sequares technique for alignment. Forf the analysis of profile tolerance of parts, the actual measured points are obtained by finding the closet points on the CAD geometry by the developed subdivision technique and the Tschebycheff norm is applied based on iterative fashion, giving accurate profile tolerance value. The developed inspection technique is applied to practical procedures of blade manufacturing and demonstrated high performance.

Development of Machine Vision System and Dimensional Analysis of the Automobile Front-Chassis-Module

  • Lee, Dong-Mok;Yang, Seung-Han;Lee, Sang-Ryong;Lee, Young-Moon
    • Journal of Mechanical Science and Technology
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    • v.18 no.12
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    • pp.2209-2215
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    • 2004
  • In the present research work, an automated machine vision system and a new algorithm to interpret the inspection data has been developed. In the past, the control of tolerance of front-chassis-module was done manually. In the present work a machine vision system and required algorithm was developed to carryout dimensional evaluation automatically. The present system is used to verify whether the automobile front-chassis-module is within the tolerance limit or not. The directional ability parameters related with front-chassis-module such as camber, caster, toe and king-pin angle are also determined using the present algorithm. The above mentioned parameters are evaluated by the pose of interlinks in the assembly of an automobile front-chassis-module. The location of ball-joint center is important factor to determine these parameters. A method to determine the location of ball-joint center using geometric features is also suggested in this paper. In the present work a 3-D best fitting method is used for determining the relationship between nominal design coordinate system and the corresponding feature coordinate system.

Study of Tolerance Suitability of Door Operation Mechanism on Mobile Air Handing Unit Using 3-DCS Analysis (3-DCS를 이용한 자동차 공기 분배장치의 도아 구동 기구의 공차 적합성 분석에 대한 연구)

  • Kim, Jongsu;Lee, Daewoong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.5
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    • pp.527-537
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    • 2016
  • Recent automakers are trying to be more precise with the dimension check and moving parts to guarantee high quality and satisfy customer requirements. The aim of this paper is to investigate the design tolerance suitability of door operating mechanism linked arms, lever, and cam-shaft in a mobile air handling unit. These parts are complicated because doors, arms, lever and cam-shaft are connected nonlinearly in 3D. The current tolerance analysis method poses problems in design analysis because the moving doors are reasonably suitable for the AHU function. The 3-DCS analysis method provided useful results not only in establishing the inspection criteria for the quality control of products but also in enabling economical production. As a result, the vent door had $1.62^{\circ}{\sim}1.72^{\circ}$ and the defrost door had $0.84^{\circ}{\sim}0.9^{\circ}$ for the directly connected arms operating-type. For the lever connected arm operating-type, the foot door had $2.0^{\circ}{\sim}2.24^{\circ}$ tolerance, while the tolerance values satisfied the air flow volume distribution rate criteria in the AHU. Finally, the results have confirmed the design's tolerance suitability by using 3-DCS analysis at the early design stages. Reliability can be achieved by analyzing accumulated tolerance during the sub-parts assembly process and the moving mechanism linked especially by arms, lever, and cam-shaft.

Effects of the Grinding Conditions on the Shape of Center Ground Part (연삭조건이 원통연삭 공작물 형상에 미치는 영향)

  • Cho, Jae-Il;Kim, Kang
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.7
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    • pp.61-68
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    • 1998
  • The form accuracy of parts has become an important parameter. Therefore, dimensional tolerance and geometric tolerance are used in the design stage to satisfy required quality and functions of parts. But the informations on the machining conditions, which can satisfy the assigned geometric tolerance in design, are insufficient. The objectives of this research are to study the effects of the grinding parameters such as traverse speed, work speed, depth of cut, and dwell time on the after-ground workpiece shape, and to find out the major parameters among them. The results are as follows, The effects of work speed and depth of cut on workpiece shape are negligible compared with the effect of traverse speed. There is an optimal dwell time depending on the traverse speed. The optimal dwell time is decreasing as the traverse speed is increased.

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Roundness and Dimensional Accuracy Analysis using SNCM616 Alloy Still (SNCM616 합금강을 이용한 진원도와 치수정밀도 분석)

  • Choi, Chul-Woong;Kim, Jin-Su;Shin, Mi-Jung
    • Journal of the Korean Society of Industry Convergence
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    • v.22 no.6
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    • pp.599-606
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    • 2019
  • In this study, it was aimed to find the optimal cutting conditions by measuring and analyzing the dimensional accuracy of SNCM 616 alloy steel, which is commonly used in industry, by precision hole machining using Ø25 mm and 8-blade reamer in CNC-HBM to be. As a result of the roundness and dimensional accuracy, it was found that the spindle speed had a significant effect on the dimensional tolerance value. Optimum cutting conditions are spindle speed 25 rpm and feed rate 20 mm / min.