• Journal of Powder Materials
• /
• v.20 no.4
• /
• pp.297-301
• /
• 2013

Mirror surface machining for large area flattening in the display field has a problem such as a tool wear and a increase in machining time due to large area machining. It should be studied to decrease machining time and tool wear. In this paper, multi-tool machining method using a PCD tool and a SCD tool was applied in order to decrease machining time and tool wear. Machining characteristics (cutting force, machined surface and surface roughness) of PCD tool and SCD tool were evaluated in order to apply PCD tool to flattening machining. Based on basic experiments, the PCD/SCD multi-tool method and the SCD single-tool method were compared through surface roughness and machining time for appllying large area mold machining.

• International Journal of Precision Engineering and Manufacturing
• /
• v.9 no.4
• /
• pp.32-38
• /
• 2008

This paper describes a fast tool control (FTC)-based diamond turning process for fabricating large-area high-quality micro-lens arrays. The developed FTC unit has a stroke of $48{\mu}m$ and a resonance frequency of 4.9 kHz. Micro-lens arrays were fabricated using a micro-cutting tool with a nose radius of $50{\mu}m$. The FTC unit was integrated with a force sensor so that the initial position of the micro-cutting tool with respect to the workpiece surface could be detected through monitoring the contacting force. The length and depth of the designed parabolic micro-lens profile were $190{\mu}m$ and $20{\mu}m$, respectively. A micro-lens array was fabricated on a cylinder surface over an area of ${\phi}55 mm{\times}40 mm$.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1885-1888
• /
• 2003

As high technology industries such as IT and display have developed, demand for application parts of micro lens and lens array has been extremely increasing. According to these trends, many researchers are studying on the fabrication technology for parts of the micro lens by a variety of methods such as MEMS, Lithography, LIGA and so on. In this paper, we have performed researches related to ultra precision micro lens, lens array mold and fabrication of Lenticular lens mold for three-dimensional display by using mechanical micro end-milling and fly-cutting fabrication method. Tools used in this research were a diamond tool of R 150$\mu\textrm{m}$. Cutting conditions set up feed rate, spindle revolution. depth of cut and dwell time as variables. And we analyzed surface quality variation of the processed products according to the cutting conditions, and then carried out experiments to search the optimum conditions. Through this research, we have confirmed that we can fabricate the ultra precision micro lens mold with surface roughness Ra=20nm and the holographic lens mold by using micro end-milling and fly-cutting fabrication method. Furthermore, we demonstrated problems happened in the fabrication of the micro lens and established the foundation of experimental study for formulating its improvement plan.

• Design & Manufacturing
• /
• v.14 no.2
• /
• pp.56-61
• /
• 2020

Recently, research for machining next-generation micro semiconductor processes and micro patterns has been actively conducted. In particular, it is applied to various industrial fields depending on the machining method in the case of FIB (Focused ion beam) milling. In this study, intends to deal with FIB milling machining technology for ultra-precision diamond tool fabrication technology. Ultra-precision diamond tools require nano-scale precision, and FIB milling is a useful method for nano-scale precision machining. However, FIB milling has a problem of Gaussian characteristics that are differently formed according to the beam current due to the input of an ion beam source, and there are process conditions to be considered, such as a side clearance angle problem of a diamond tool that is differently formed according to the tilting angle. A series of process steps for fabrication a ultra-precision diamond tool were studied and analyzed for each process. It was confirmed that the effect on the fabrication process was large depending on the spot size of the beam and the current of the beam as a result of the experimental analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.449-450
• /
• 2008

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2005.05a
• /
• pp.313-318
• /
• 2005

The present study deals design and manufacture of automatic polishing machine that can cut diamond to have 58 facets in a brilliant cutting which has been hardly achieved by a conventional manually operating polishing machine. Upon the 3-dimensional Sarin M/C test and analysis on the diamond processed by the automatic polishing machine developed in this study its proportion and finishing turned out to be better than the diamond processed by the conventional method, by being rated as 'very good'.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.49-52
• /
• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface contours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining processprohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normalto the face of the workpice can be filterd through an appropriate admittance transfer function to result in the estimated depth of cut. This can be compared to the desired depth of cut to generate the adjustment cotnrol action in addition to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. Based on the empirical data of the cutting dynamics, simulation results are shown.

• International Journal of Precision Engineering and Manufacturing-Green Technology
• /
• v.5 no.5
• /
• pp.571-581
• /
• 2018

In the present study, monitoring of elliptical vibration cutting process by utilizing internal data in the ultrasonic elliptical vibration device without external sensors such as a dynamometer and displacement sensor is investigated. The internal data utilized here is the change of excitation frequency, i.e. resonant frequency of the device, voltages applied to the piezoelectric actuators composing the device, and electric currents flowing through the actuators. These internal data change automatically in the elliptical vibration control system in order to keep a constant elliptical vibration against the change of the cutting process. Correlativity between the process and the internal data is described by using a vibration model of ultrasonic elliptical vibration cutting and verified by several experiments, i.e. planing and mirror surface finishing of hardened die steel carried out with single crystalline diamond tools. As a result, it is proved that it is possible to estimate the elements of elliptical vibration cutting process, e.g. tool wear and machining load, which are important for stable cutting in such precision machining.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.04a
• /
• pp.59-64
• /
• 2002

One of the exciting research areas of the X-ray microscope is the observation of a living cell. In order to study a living cell with high resolution the order of the several tens nm, we need to improve the efficiency of mirrors which are components of an X-ray microscope system. In this paper we present the mirror design and manufacture to give a high resolution and reflectivity. We designed Wolter type I the condenser and objective mirror with the several tens of nm resolution. According to mirror design. we made the program using the visual basic. Using the new processing method as well as the ultra-precision diamond cutting, we directly processed the inside of an aluminum hulk in order to manufacture mirrors. From the experimental result, we think that the new processing method will improve a high reflectivity through the improved cutting tools and optimum cutting conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.629-630
• /
• 2008