• Title/Summary/Keyword: High Speed Precision Machining

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Spark Plasma Sintering and Ultra-Precision Machining Characteristics of SiC

  • Son, Hyeon-Taek;Kim, Dae-Guen;Park, Soon-Sub;Lee, Jong-Hyeon
    • Korean Journal of Materials Research
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    • v.20 no.11
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    • pp.559-569
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    • 2010
  • The liquid-phase sintering method was used to prepare a glass lens forming core composed of SiC-$Al_2O_3-Y_2O_3$. Spark plasma sintering was used to obtain dense sintered bodies. The sintering characteristics of different SiC sources and compositions of additives were studied. Results revealed that, owing to its initial larger surface area, $\alpha$-SiC offers sinterability that is superior to that of $\beta$-SiC. A maximum density of $3.32\;g/cm^3$ (theoretical density [TD] of 99.7%) was obtained in $\alpha$-SiC-10 wt% ($6Al_2O_3-4Y_2O_3$) sintered at $1850^{\circ}C$ without high-energy ball milling. The maximum hardness and compression stress of the sintered body reached 2870 Hv and 1110 MPa, respectively. The optimum ultra-precision machining parameters were a grinding speed of 1243 m/min, work spindle rotation rate of 100 rpm, feed rate of 0.5 mm/min, and depth of cut of $0.2\;{\mu}m$. The surface roughnesses of the thus prepared final products were Ra = 4.3 nm and Rt = 55.3 nm for the aspheric lens forming core and Ra = 4.4 nm and Rt = 41.9 for the spherical lens forming core. These values were found to be sufficiently low, and the cores showed good compatibility between SiC and the diamond-like carbon (DLC) coating material. Thus, these glass lens forming cores have great potential for application in the lens industry.

FPCB Cutting Process using ns and ps Laser (나노초 및 피코초 레이저를 이용한 FPCB의 절단특성 분석)

  • Shin, Dong-Sig;Lee, Jae-Hoon;Sohn, Hyon-Kee;Paik, Byoung-Man
    • Laser Solutions
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    • v.11 no.4
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    • pp.29-34
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    • 2008
  • Ultraviolet laser micromachining has increasingly been applied to the electronics industry where precision machining of high-density, multi-layer, and multi material components is in a strong demand. Due to the ever-decreasing size of electronic products such as cellular phones, MP3 players, digital cameras, etc., flexible printed circuit board (FPCB), multi-layered with polymers and metals, tends to be thicker. In present, multi-layered FPCBs are being mechanically cut with a punching die. The mechanical cutting of FPCBs causes such defects as burr on layer edges, cracks in terminals, delamination and chipping of layers. In this study, the laser cutting mechanism of FPCB was examined to solve problems related to surface debris and short-circuiting that can be caused by the photo-thermal effect. The laser cutting of PI and FCCL, which are base materials of FPCB, was carried out using a pico-second laser(355nm, 532nm) and nano-second UV laser with adjusting variables such as the average/peak power, scanning speed, cycles, gas and materials. Points which special attention should be paid are that a fast scanning speed, low repetition rate and high peak power are required for precision machining.

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Development of Control System of High-speed ATC of Machining Center (Machining Center의 고속 ATC 제어 시스템의 개발)

  • Han, Dong-Chang;Lee, Dong-Il;Song, Yong-Tae;Lee, Seok-Gyu
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.9
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    • pp.125-132
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    • 2002
  • We use a compound-cam twin arm structure and random tool access method to achieve a faster ATC (Automatic Tool Changer) system for the accurate position and rotation control of a tool magazine and an exchange am. Based on the data obtained from various sensors, it is possible to follow the sequence of commands in each control step for an exchange arm. However, it is not so easy to reduce the exchange time of the system because of the slow responses of the sensors and execution mode delays of PLC (Programmable Logic Controller) scan time. In this paper, we propose a new programmed limit-switch position control method to obtain the shortest possible delays for the random tool access method and compound-cam twin arm structure. With some experimental results, we have achieved below 0.9sec tool exchange time with the proposed method.

The Effects of Design Parameters on the Mechanical Precision of an End Effector on a Parallel Kinematic Robot (병렬로봇의 설계공차 설정에 따른 기계적 정밀도의 영향 분석)

  • Park, Chanhun;Kim, Doohyung;Do, Hyunmin;Choi, Taeyong;Park, Dongil;Kim, Byungin
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.10
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    • pp.847-852
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    • 2016
  • In this paper, important design parameters for parallel kinematic robots are defined, paying special attention to machining errors which may cause kinematic errors at the end effector of a robot. The kinematic effects caused by each design parameter, as well as their upper/lower limits, are analyzed here. To do so, we have developed a novel software program to compute kinematic errors by considering its defined design parameters. With this program, roboticists designing parallel kinematic robots can understand the important design parameters for which upper/lower allowances have to be strictly controlled in the design process. This tactic can be used for the design of high-speed, parallel kinematic robots to reduce the design/manufacturing costs and increase kinematic precision.

Evaluation of Grinding Machining Characteristics of $ZrO_2$ Ferrule Using the Taguchi Method (다구치 방법을 이용한 지르코니아 세라믹스 페룰의 연삭 가공 특성 평가)

  • 김기환;최영재;홍원표;이석우;최헌종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.516-519
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    • 2004
  • As the optical communication industry is developed, the demand of optical communication part is increasing. ZrO$_2$ ceramic ferrule is very important part which can determines the transmission efficiency and information quality to connect the optical fibers. In general ZrO$_2$ ceramic ferrule is manufactured by grinding process because the demands precision is very high. And the co-axle grinding process of ZrO$_2$ ceramic ferrule is to make its concentricity all of uniform before centerless grinding. This paper deals with the analysis of the process parameters such as grinding wheel speed, grinding feedrate and regulating wheel speed as influential factors, on the concentricity and surface finish developed based on Taguchi's experimental design methods. Taguchi s tools such as orthogonal array, signal-to-noise ratio, factor effect analysis, etc. have been used for this purpose optimal condition has been found out. Thus, if possible be finding highly efficient and quality grinding conditions.

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Performance Assessment of Linear Motor for High Speed Machining Center (고속 HMC 이송계의 운동 특성 평가)

  • 홍원표;강은구;이석우;최헌종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.158-161
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    • 2003
  • Recently, the evolution in production techniques (e.g. high-speed milling), the complex shapes involved in modem production design, and the ever increasing pressure for higher productivity demand a drastic improvement of the dynamic behavior of the machine tool axes used in production machinery. And also machine tools of multi functional and minimized parts are increasingly required as demand of higher accurate in some fields such as electronic and optical components etc. The accuracy and the productivity of machined parts are natural to depend on the linear system of machine tools. The complex workpiece surfaces encountered in present-day products and generated by CAD systems are to be transformed into tool paths for machine tools. The more complex these tool paths and the higher the speed requirements, the higher the acceleration requirements are needed to the machine tool axes and the motion control system, and the more difficult it is to meet the requirements. The traditional indirect drive design for high speed machine tools, which consists of a rotary motor with a ball-screw transmission to the slide, is limited in speed, acceleration, and accuracy. The direct drive design of machine tool axes. which is based on linear motors and which recently appeared on the market. is a viable candidate to meet the ever increasing demands, because of these advantages such as no backlash, less friction, no mechanical limitations on acceleration and velocity and mechanical simplicity. Therefore performance tests were carried out to machine tool axes based on linear motor. Especially, dynamic characteristics were investigated through circular test.

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Multi-step design optimization of a high speed machine tool structure using a genetic algorithm with dynamic penalty (동적 벌점함수 유전 알고리즘과 다단계 설계방법을 이용한 공작기계 구조물의 설계 최적화)

  • 최영휴;배병태;김태형;박보선
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.108-113
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    • 2002
  • This paper presents a multi-step structural design optimization method fur machine tool structures using a genetic algorithm with dynamic penalty. The first step is a sectional topology optimization, which is to determine the best sectional construction that minimize the structural weight and the compliance responses subjected to some constraints. The second step is a static design optimization, in which the weight and the static compliance response are minimized under some dimensional and safety constraints. The third step is a dynamic design optimization, where the weight static compliance, and dynamic compliance of the structure are minimized under the same constraints. The proposed design method was examined on the 10-bar truss problem of topology and sizing optimization. And the results showed that our solution is better than or just about the same as the best one of the previous researches. Furthermore, we applied this method to the topology and sizing optimization of a crossbeam slider for a high-speed machining center. The topology optimization result gives the best desirable cross-section shape whose weight was reduced by 38.8% than the original configuration. The subsequent static and dynamic design optimization reduced the weight, static and dynamic compliances by 5.7 %, 2.1% and 19.1% respectively from the topology-optimized model. The examples demonstrated the feasibility of the suggested design optimization method.

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Efficient Arc Detection and Control Method in Electro-discharge Machining (방전가공기의 효율적인 아크 검출과 제어방법)

  • Park, Yang-Jae
    • Journal of Digital Convergence
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    • v.16 no.12
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    • pp.309-315
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    • 2018
  • In this paper, propose an efficient arc detection and control method to achieve fast machining speed, improved precision and surface roughness in discharge machining, especially for carbide and hard material processing and metal processing using discharge phenomenon as energy. A single discharge waveform is divided into three sections of Td (Time-Delay), Ton (Time-on) and Toff (Time-off) and the gate control timing is simulated using the HDL language. In this paper, we analyze the effect of the gap between the electrode and the workpiece on the machining results by determining the operation of the servo mechanism by sampling the Td section through the comparator circuit. As a result of the analysis, the Td section of the formed waveform was more precisely sampled at a high speed and the results were improved when applied to the gap control between the electrode and the workpiece.

A Study on the Manufacturing Characteristics for Micro Spherical Lens Mold of Soft Materials (연질재료의 마이크로 구형렌즈금형 가공특성에 관한 연구)

  • 홍성민;이동주;제태진;최두선;이응숙
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.1466-1469
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    • 2004
  • Micro spherical lens mold processing method based on mechanical one completes a spherical shape by setting a diamond tool of hundreds $\mu$m radius on spins with high speed and then using Z-axis vertical feeding motion like the fabrication of micro drilling. In this method, we can see unprocessed parts shaped like cylinder and cone and check increasing chatter marks and burrs by setting errors of the central axis of rotation on the edge of the tool. That is why this method doesn't suit for the optical lens mold. In this paper presents unprocessed parts are disappeared and chatter marks and burrs are decreased from centre of the lens after using Run-out measuring and setting system on run-out occurred from setting tool. Also the fabrication characteristics of 6:4 Brass, A1601, PMMA are compared and analyzed, establishing the optimum machining condition on each material.

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A study on thermal characteristics of linear motor for high speed machining tools (공작기계 고속이송용 리니어 모터의 열 특성에 관한 연구)

  • 정일용;강은구;이석우;최헌종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.98-101
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    • 2001
  • Linear motor feature a direct connection to the machine tool, therefore a direct route for heat transfer. The heat dissipation of linear motor machine is affected by the maximum temperature rise of the primary part, coil and the cooling method. To minimize temperature induced dimension changes and decrements of performance, linear motor machine require effective cooling mechanism. To evaluate cooling performance of existing linear motor machine, some experiments about temperature profile are performed using thermocouple recorder. Due to the lack of information about internal structure, only some finite element modeling is prepared and analyzed.

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