• International Journal of CAD/CAM
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• v.6 no.1
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• pp.183-192
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• 2006

A CAD/CAM system has been developed for rapid prototyping (RP) of microfluidic devices based on excimer laser micromachining. The system comprises of two complementary softwares. One, the CAM tool, creates part programs from CAD models. The other, the Simulator Tool, uses a part program to generate the laser tool path and the 2D and 3D graphical representation of the machined microstructure. The CAM tool's algorithms use the 3D geometry of a microstructure, defined as an STL file exported from a CAD system, and process parameters (laser fluence, pulse repetition frequency, number of shots per area, wall angle), to automatically generate Numerical Control (NC) part programs for the machine controller. The performance of the system has been verified and demonstrated by machining a particle transportation device. The CAM tool simplifies part programming and replaces the tedious trial-and-error approach to creating programs. The simulator tool accepts manual or computer generated part programs, and displays the tool path and the machined structure. This enables error checking and editing of the program before machining, and development of programs for complex microstructures. Combined, the tools provide a user-friendly CAD/CAM system environment for rapid prototyping of microfluidic devices.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.74-79
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• 2001

In this two-part paper, a virtual machine tool (VMT) is presented. In part 1, the analytical foundation of a virtual machining system, envisioned as the foundation for a comprehensive simulation environment capable of predicting the outcome of cutting processes, is developed. The VMT system purposes to experience the pseudo-real machining before real cutting with a CNC machine tool, to provide the proper cutting conditions for process planners, and to compensate or control the machining process in terms of the productivity and attributes of products. The attributes can be characterized with the machined surface error, dimensional accuracy, roughness, integrity and so forth. The main components of the VMT are cutting process, application, thermal behavior and feed drive modules. In part 1, the cutting process module is presented. The proposed models were verified experimentally and gave significantly better prediction results than any other method. The thermal behavior and feed drive modules are developed in part 2 paper. The developed models are integrated as a comprehensive software environment in part 2 paper.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.431-439
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• 2014

Recently, a demand for precision 5-axis machine tools is significantly increasing, and the maintenance of machine tool accuracy becomes more important. it is very difficult to evaluate to accuracy of 5-axis M/C in the production site since it needs expensive measuring equipment and skilled engineer. On the other hand, evaluation items of 5-axis M/C are not systematically organized in the existing KS and ISO standards. In this study, the evaluation items for 5-axis M/C were derived systematically and a test workpiece was developed to evaluate the machine tool accuracy more easily. The error sources of machine tool can be estimated by machining and measuring of the test workpiece. The correlation between the machine tool accuracy and the accuracy of machined test workpiece was analyzed. As a result, the accuracy of machined test workpiece represented the accuracy of machine tool and the error sources very effectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.3
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• pp.58-66
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• 1995

It is very important to test motion accuracy and performance of NC machine tools as they affect that of all other machines machined by them in industry. In this paper, in has become possible to detect errors of linear displacement of radial direction for circular motion test using newly assembled magnetic type of linear scales so called Magnescale ball bar system, and to calculate time interval getting error motion data and revolution angle of circular motion in machining center using tick pulses come out from computer. And a set of error data gotten from test is expressed to a plot by computer treatment and to numerics of error motion by statistical treatment and results of test are compared with those of Renishaw ball bar system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.227-230
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• 1999

In this paper, the machining characteristics of high speed ball end milling affected by the rotational error of high speed spindle using air bearing are investigated. The error motions of a spindle have generally influenced on the surface roughness, the form accuracy, the tool life, etc. in end milling. Experiments are carried out over a wide range of rotational speeds(10,000-50,000rpm). The rotational errors of the spindle are measured by the gap sensor mounted on the spindle shaft at various cutting speeds. The relations between the surface roughness and the spindle error motion are presented. Results show that the rotational accuracy of the spindle directly affects the surface roughness of the machined surface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1227-1233
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• 2003

NURBS (Non Uniform Rational B-Spline) is widely used in CAD system and NC data for high speed machining. Conventional CAM system changes NURBS surface to tessellated meshes or Z-map model, and produces linear tool path. The linear tool path is not good fur precise machining and high speed machining. In this paper, an algorithm to change linear tool path to NURBS one was studied and the machining result of NURBS tool path was compared with that of linear tool path. The N-post including both a post-processing and a virtual machining software was developed. The N-Post transforms linear tool path to NURBS tool path and quickly shades a machined product on OpenGL view, while comparing a machined surface with a original CAD one. A virtulal machined model of original tool path and post-processed tool path was compared to original CAD model. The machining error and machining time of post-processed NURBS tool path were investigated.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1111-1117
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• 2003

NURBS (Non Uniform Rational B-Spline) is widely used in CAD system and NC data for high speed machining. Conventional CAM system changes NURBS surface to tessellated meshes or Z-map model, and produces linear tool path. The linear tool path is not good for precise machining and high speed machining. In this paper, an algorithm to change linear tool path to NURBS one was studied, and the machining result of NURBS tool path was compared with that of linear tool path. The N-post, post-processing and virtual machining software was developed. The N-Post post-processes linear tool path to NURBS tool path and quickly shades machined product on OpenGL view and compares a machined product with original CAD surface. A virtual machined model of original tool path and post-processed tool path was compared to original CAD model. The machining error of post-processed NURBS tool path was reduced to 43%. The original tool path and NURBS tool path was used to machine general model using same machine tool and machining condition. The machining time of post-processed NURBS tool path was reduced up to 38%.

• Design & Manufacturing
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• v.14 no.1
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• pp.63-68
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• 2020

Ultra-high brightness and thin displays need to optical micro-patterns which can uniformly diffuse the lights and low loss. The micro random patterns have characteristics to rise the optical efficiency such as light extraction, uniform diffusion. For this reason, various fabrication processes are studied for random patterns. In this study, the micro random patterns were machined by diamond turning which used a controlled cutting tool path with random cutting depth. The machined patterns had random shape and directionality along the circumferential direction. The average width and length of machined random pattern according to rotation radius were 40.13㎛~55.51㎛ and 37.25㎛~59.49㎛, and these results were compared with the designed result. Also, the machining error according to rotation radius in diamond turning using randomly controlled cutting depth was discussed.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.66-73
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• 2002

Since cross-feed directional cutting force which is normal to machined surface directly influences the machined surface of the workpiece and total force loaded in cutter, it is necessary to estimate this force to control the roughness of the machined surface and total force in cutter. However, there have been difficulties in using the current existing in a stationary motor for cutting state prediction because of some unpredictable behavior of the current. Empirical approach was conducted to resolve the problem. As a result, we showed that the current and its unpredictable behavior are related to the infinitesimal rotation of the motor. Subsequently, the relationship between the current and the cutting force was identified with the error less than 50%. And, the estimation results of the two machine tools with different characteristics were compared to each other to confirm the validity of the presented estimation method and the characteristics of current of the stationary feed motor.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.2
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• pp.55-61
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• 2005

The machining Parts must be Produced within the specification of drawing and those will be able to meet faction and efficiency. At that time, it is very important not only precision machine and machining technique but also the measurement technique. So, the improvement of measurement technique is to be joined together at once with improvement of machining technique. Finally, the quality and value of the parts are decided by precision measurement. This paper aims to study on the measurement uncertainty when the machined parts are inspected with 3-dimensional coordinate measuring machine. The objectives remove an error of measurement and remove a quality of mass products.